enhanced ending operator detection

ast.go

@@ -5,7 +5,10 @@
 package expr
 
 import (
+	"errors"
 	"strings"
+
+	"git.portale-stac.it/go-pkg/expr/kern"
 )
 
 //-------- ast
@@ -19,33 +22,33 @@ func NewAst() *ast {
 	return &ast{}
 }
 
-func (expr *ast) TypeName() string {
+func (ast *ast) TypeName() string {
 	return "Expression"
 }
 
-func (expr *ast) ToForest() {
-	if expr.root != nil {
-		if expr.forest == nil {
-			expr.forest = make([]*term, 0)
+func (ast *ast) ToForest() {
+	if ast.root != nil {
+		if ast.forest == nil {
+			ast.forest = make([]*term, 0)
 		}
-		expr.forest = append(expr.forest, expr.root)
-		expr.root = nil
+		ast.forest = append(ast.forest, ast.root)
+		ast.root = nil
 	}
 }
 
-func (expr *ast) String() string {
+func (ast *ast) String() string {
 	var sb strings.Builder
-	if expr.root == nil {
+	if ast.root == nil {
 		sb.WriteString("(nil)")
 	} else {
-		expr.root.toString(&sb)
+		ast.root.toString(&sb)
 	}
 	return sb.String()
 }
 
-func (expr *ast) addTokens(tokens ...*Token) (err error) {
+func (ast *ast) addTokens(tokens ...*Token) (err error) {
 	for _, tk := range tokens {
-		if _, err = expr.addToken(tk); err != nil {
+		if _, err = ast.addToken(tk); err != nil {
 			break
 		}
 	}
@@ -57,31 +60,31 @@ func (expr *ast) addTokens(tokens ...*Token) (err error) {
 // 	return
 // }
 
-func (expr *ast) addToken(tk *Token) (t *term, err error) {
+func (ast *ast) addToken(tk *Token) (t *term, err error) {
 	if t = newTerm(tk); t != nil {
-		err = expr.addTerm(t)
+		err = ast.addTerm(t)
 	} else {
 		err = tk.Errorf("unexpected token %q", tk.String())
 	}
 	return
 }
 
-func (expr *ast) addTerm(node *term) (err error) {
-	if expr.root == nil {
-		expr.root = node
+func (ast *ast) addTerm(node *term) (err error) {
+	if ast.root == nil {
+		ast.root = node
 	} else {
-		expr.root, err = expr.insert(expr.root, node)
+		ast.root, err = ast.insert(ast.root, node)
 	}
 	return
 }
 
-func (expr *ast) insert(tree, node *term) (root *term, err error) {
+func (ast *ast) insert(tree, node *term) (root *term, err error) {
 	if tree.getPriority() < node.getPriority() {
 		root = tree
 		if tree.isComplete() {
 			var subRoot *term
 			last := tree.removeLastChild()
-			if subRoot, err = expr.insert(last, node); err == nil {
+			if subRoot, err = ast.insert(last, node); err == nil {
 				subRoot.setParent(tree)
 			}
 		} else {
@@ -96,22 +99,32 @@ func (expr *ast) insert(tree, node *term) (root *term, err error) {
 	return
 }
 
-func (expr *ast) Finish() {
-	if expr.root == nil && expr.forest != nil && len(expr.forest) >= 1 {
-		expr.root = expr.forest[len(expr.forest)-1]
-		expr.forest = expr.forest[0 : len(expr.forest)-1]
+func (ast *ast) Finish() {
+	if ast.root == nil && ast.forest != nil && len(ast.forest) >= 1 {
+		ast.root = ast.forest[len(ast.forest)-1]
+		ast.forest = ast.forest[0 : len(ast.forest)-1]
 	}
 }
 
-func (expr *ast) Eval(ctx ExprContext) (result any, err error) {
-	expr.Finish()
+func (ast *ast) Eval(ctx kern.ExprContext) (result any, err error) {
+	defer func() {
+		if r := recover(); r != nil {
+			if errVal, ok := r.(error); ok {
+				err = errVal
+			} else {
+				err = errors.New("unexpected error while evaluating the expression")
+			}
+		}
+	}()
 
-	if expr.root != nil {
+	ast.Finish()
+
+	if ast.root != nil {
 		// initDefaultVars(ctx)
-		if expr.forest != nil {
-			for _, root := range expr.forest {
-				if result, err = root.compute(ctx); err == nil {
-					ctx.UnsafeSetVar(ControlLastResult, result)
+		if ast.forest != nil {
+			for _, tree := range ast.forest {
+				if result, err = tree.Compute(ctx); err == nil {
+					ctx.UnsafeSetVar(kern.ControlLastResult, result)
 				} else {
 					//err = fmt.Errorf("error in expression nr %d: %v", i+1, err)
 					break
@@ -119,8 +132,8 @@ func (expr *ast) Eval(ctx ExprContext) (result any, err error) {
 			}
 		}
 		if err == nil {
-			if result, err = expr.root.compute(ctx); err == nil {
-				ctx.UnsafeSetVar(ControlLastResult, result)
+			if result, err = ast.root.Compute(ctx); err == nil {
+				ctx.UnsafeSetVar(kern.ControlLastResult, result)
 			}
 		}
 		// } else {

bind-expr-functions.go

@@ -4,20 +4,24 @@
 // function.go
 package expr
 
+import (
+	"git.portale-stac.it/go-pkg/expr/kern"
+)
+
 // ---- Linking with Expr functions
 type exprFunctor struct {
-	baseFunctor
-	params []ExprFuncParam
+	kern.BaseFunctor
+	params []kern.ExprFuncParam
 	expr   Expr
-	defCtx ExprContext
+	defCtx kern.ExprContext
 }
 
-func (functor *exprFunctor) GetParams() (params []ExprFuncParam) {
+func (functor *exprFunctor) GetParams() (params []kern.ExprFuncParam) {
 	return functor.params
 }
 
-func newExprFunctor(e Expr, params []ExprFuncParam, ctx ExprContext) *exprFunctor {
-	var defCtx ExprContext
+func newExprFunctor(e Expr, params []kern.ExprFuncParam, ctx kern.ExprContext) *exprFunctor {
+	var defCtx kern.ExprContext
 	if ctx != nil {
 		defCtx = ctx
 	}
@@ -28,17 +32,17 @@ func (functor *exprFunctor) TypeName() string {
 	return "ExprFunctor"
 }
 
-func (functor *exprFunctor) GetDefinitionContext() ExprContext {
+func (functor *exprFunctor) GetDefinitionContext() kern.ExprContext {
 	return functor.defCtx
 }
 
-func (functor *exprFunctor) InvokeNamed(ctx ExprContext, name string, args map[string]any) (result any, err error) {
+func (functor *exprFunctor) InvokeNamed(ctx kern.ExprContext, name string, args map[string]any) (result any, err error) {
 	var missing []string
 	for _, p := range functor.params {
 		if arg, exists := args[p.Name()]; exists {
-			if funcArg, ok := arg.(Functor); ok {
+			if funcArg, ok := arg.(kern.Functor); ok {
 				paramSpecs := funcArg.GetParams()
-				ctx.RegisterFunc(p.Name(), funcArg, TypeAny, paramSpecs)
+				ctx.RegisterFunc(p.Name(), funcArg, kern.TypeAny, paramSpecs)
 			} else {
 				ctx.UnsafeSetVar(p.Name(), arg)
 			}
@@ -51,7 +55,7 @@ func (functor *exprFunctor) InvokeNamed(ctx ExprContext, name string, args map[s
 		}
 	}
 	if missing != nil {
-		err = ErrMissingParams(name, missing)
+		err = kern.ErrMissingParams(name, missing)
 	} else {
 		result, err = functor.expr.Eval(ctx)
 	}

builtin-base.go

@@ -9,81 +9,83 @@ import (
 	"math"
 	"strconv"
 	"strings"
+
+	"git.portale-stac.it/go-pkg/expr/kern"
 )
 
 const (
 	ParamDenominator = "denominator"
 )
 
-func isNilFunc(ctx ExprContext, name string, args map[string]any) (result any, err error) {
-	result = args[ParamValue] == nil
+func isNilFunc(ctx kern.ExprContext, name string, args map[string]any) (result any, err error) {
+	result = args[kern.ParamValue] == nil
 	return
 }
 
-func isIntFunc(ctx ExprContext, name string, args map[string]any) (result any, err error) {
-	result = IsInteger(args[ParamValue])
+func isIntFunc(ctx kern.ExprContext, name string, args map[string]any) (result any, err error) {
+	result = kern.IsInteger(args[kern.ParamValue])
 	return
 }
 
-func isFloatFunc(ctx ExprContext, name string, args map[string]any) (result any, err error) {
-	result = IsFloat(args[ParamValue])
+func isFloatFunc(ctx kern.ExprContext, name string, args map[string]any) (result any, err error) {
+	result = kern.IsFloat(args[kern.ParamValue])
 	return
 }
 
-func isBoolFunc(ctx ExprContext, name string, args map[string]any) (result any, err error) {
-	result = IsBool(args[ParamValue])
+func isBoolFunc(ctx kern.ExprContext, name string, args map[string]any) (result any, err error) {
+	result = kern.IsBool(args[kern.ParamValue])
 	return
 }
 
-func isStringFunc(ctx ExprContext, name string, args map[string]any) (result any, err error) {
-	result = IsString(args[ParamValue])
+func isStringFunc(ctx kern.ExprContext, name string, args map[string]any) (result any, err error) {
+	result = kern.IsString(args[kern.ParamValue])
 	return
 }
 
-func isFractionFunc(ctx ExprContext, name string, args map[string]any) (result any, err error) {
-	result = IsFract(args[ParamValue])
+func isFractionFunc(ctx kern.ExprContext, name string, args map[string]any) (result any, err error) {
+	result = kern.IsFraction(args[kern.ParamValue])
 	return
 }
 
-func isRationalFunc(ctx ExprContext, name string, args map[string]any) (result any, err error) {
-	result = IsRational(args[ParamValue])
+func isRationalFunc(ctx kern.ExprContext, name string, args map[string]any) (result any, err error) {
+	result = kern.IsRational(args[kern.ParamValue])
 	return
 }
 
-func isListFunc(ctx ExprContext, name string, args map[string]any) (result any, err error) {
-	result = IsList(args[ParamValue])
+func isListFunc(ctx kern.ExprContext, name string, args map[string]any) (result any, err error) {
+	result = kern.IsList(args[kern.ParamValue])
 	return
 }
 
-func isDictionaryFunc(ctx ExprContext, name string, args map[string]any) (result any, err error) {
-	result = IsDict(args[ParamValue])
+func isDictionaryFunc(ctx kern.ExprContext, name string, args map[string]any) (result any, err error) {
+	result = kern.IsDict(args[kern.ParamValue])
 	return
 }
 
-func boolFunc(ctx ExprContext, name string, args map[string]any) (result any, err error) {
-	switch v := args[ParamValue].(type) {
+func boolFunc(ctx kern.ExprContext, name string, args map[string]any) (result any, err error) {
+	switch v := args[kern.ParamValue].(type) {
 	case int64:
 		result = (v != 0)
-	case *FractionType:
-		result = v.num != 0
+	case *kern.FractionType:
+		result = v.N() != 0
 	case float64:
 		result = v != 0.0
 	case bool:
 		result = v
 	case string:
 		result = len(v) > 0
-	case *ListType:
+	case *kern.ListType:
 		result = len(*v) > 0
-	case *DictType:
+	case *kern.DictType:
 		result = len(*v) > 0
 	default:
-		err = ErrCantConvert(name, v, "bool")
+		err = kern.ErrCantConvert(name, v, "bool")
 	}
 	return
 }
 
-func intFunc(ctx ExprContext, name string, args map[string]any) (result any, err error) {
-	switch v := args[ParamValue].(type) {
+func intFunc(ctx kern.ExprContext, name string, args map[string]any) (result any, err error) {
+	switch v := args[kern.ParamValue].(type) {
 	case int64:
 		result = v
 	case float64:
@@ -99,16 +101,16 @@ func intFunc(ctx ExprContext, name string, args map[string]any) (result any, err
 		if i, err = strconv.Atoi(v); err == nil {
 			result = int64(i)
 		}
-	case *FractionType:
-		result = int64(v.num / v.den)
+	case *kern.FractionType:
+		result = int64(v.N() / v.D())
 	default:
-		err = ErrCantConvert(name, v, "int")
+		err = kern.ErrCantConvert(name, v, "int")
 	}
 	return
 }
 
-func decFunc(ctx ExprContext, name string, args map[string]any) (result any, err error) {
-	switch v := args[ParamValue].(type) {
+func decFunc(ctx kern.ExprContext, name string, args map[string]any) (result any, err error) {
+	switch v := args[kern.ParamValue].(type) {
 	case int64:
 		result = float64(v)
 	case float64:
@@ -124,16 +126,16 @@ func decFunc(ctx ExprContext, name string, args map[string]any) (result any, err
 		if f, err = strconv.ParseFloat(v, 64); err == nil {
 			result = f
 		}
-	case *FractionType:
-		result = v.toFloat()
+	case *kern.FractionType:
+		result = v.ToFloat()
 	default:
-		err = ErrCantConvert(name, v, "float")
+		err = kern.ErrCantConvert(name, v, "float")
 	}
 	return
 }
 
-func stringFunc(ctx ExprContext, name string, args map[string]any) (result any, err error) {
-	switch v := args[ParamValue].(type) {
+func stringFunc(ctx kern.ExprContext, name string, args map[string]any) (result any, err error) {
+	switch v := args[kern.ParamValue].(type) {
 	case int64:
 		result = strconv.FormatInt(v, 10)
 	case float64:
@@ -146,118 +148,118 @@ func stringFunc(ctx ExprContext, name string, args map[string]any) (result any,
 		}
 	case string:
 		result = v
-	case *FractionType:
+	case *kern.FractionType:
 		result = v.ToString(0)
-	case Formatter:
+	case kern.Formatter:
 		result = v.ToString(0)
 	case fmt.Stringer:
 		result = v.String()
 	default:
-		err = ErrCantConvert(name, v, "string")
+		err = kern.ErrCantConvert(name, v, "string")
 	}
 	return
 }
 
-func fractFunc(ctx ExprContext, name string, args map[string]any) (result any, err error) {
-	switch v := args[ParamValue].(type) {
+func fractFunc(ctx kern.ExprContext, name string, args map[string]any) (result any, err error) {
+	switch v := args[kern.ParamValue].(type) {
 	case int64:
 		var den int64 = 1
 
 		var ok bool
 		if den, ok = args[ParamDenominator].(int64); !ok {
-			err = ErrExpectedGot(name, "integer", args[ParamDenominator])
+			err = kern.ErrExpectedGot(name, "integer", args[ParamDenominator])
 		} else if den == 0 {
-			err = ErrFuncDivisionByZero(name)
+			err = kern.ErrFuncDivisionByZero(name)
 		}
 
 		if err == nil {
-			result = newFraction(v, den)
+			result = kern.NewFraction(v, den)
 		}
 	case float64:
-		result, err = float64ToFraction(v)
+		result, err = kern.Float64ToFraction(v)
 	case bool:
 		if v {
-			result = newFraction(1, 1)
+			result = kern.NewFraction(1, 1)
 		} else {
-			result = newFraction(0, 1)
+			result = kern.NewFraction(0, 1)
 		}
 	case string:
-		result, err = makeGeneratingFraction(v)
-	case *FractionType:
+		result, err = kern.MakeGeneratingFraction(v)
+	case *kern.FractionType:
 		result = v
 	default:
-		err = ErrCantConvert(name, v, "float")
+		err = kern.ErrCantConvert(name, v, "float")
 	}
 	return
 }
 
-// func iteratorFunc(ctx ExprContext, name string, args []any) (result any, err error) {
+// func iteratorFunc(ctx expr.ExprContext, name string, args []any) (result any, err error) {
 // 	return
 // }
 
-func evalFunc(ctx ExprContext, name string, args map[string]any) (result any, err error) {
-	if source, ok := args[ParamSource].(string); ok {
-		var expr Expr
+func evalFunc(ctx kern.ExprContext, name string, args map[string]any) (result any, err error) {
+	if source, ok := args[kern.ParamSource].(string); ok {
+		var ast Expr
 
 		parser := NewParser()
 		if ctx == nil {
-			ctx = NewSimpleStore()
+			ctx = NewSimpleStoreWithoutGlobalContext()
 		}
 
 		r := strings.NewReader(source)
 		scanner := NewScanner(r, DefaultTranslations())
 
-		if expr, err = parser.Parse(scanner); err == nil {
-			CtrlEnable(ctx, control_export_all)
-			result, err = expr.Eval(ctx)
+		if ast, err = parser.Parse(scanner); err == nil {
+			CtrlEnable(ctx, kern.ControlExportAll)
+			result, err = ast.Eval(ctx)
 		}
 	} else {
-		err = ErrWrongParamType(name, ParamSource, TypeString, args[ParamSource])
+		err = kern.ErrWrongParamType(name, kern.ParamSource, kern.TypeString, args[kern.ParamSource])
 	}
 	return
 }
 
-func varFunc(ctx ExprContext, name string, args map[string]any) (result any, err error) {
+func varFunc(ctx kern.ExprContext, name string, args map[string]any) (result any, err error) {
 	var varName string
 	var ok bool
 
-	if varName, ok = args[ParamName].(string); !ok {
-		return nil, ErrWrongParamType(name, ParamName, TypeString, args[ParamName])
+	if varName, ok = args[kern.ParamName].(string); !ok {
+		return nil, kern.ErrWrongParamType(name, kern.ParamName, kern.TypeString, args[kern.ParamName])
 	}
 
-	if result, ok = args[ParamValue]; ok && result != nil {
+	if result, ok = args[kern.ParamValue]; ok && result != nil {
 		ctx.GetParent().UnsafeSetVar(varName, result)
 		// } else {
-		// 	err = ErrWrongParamType(name, ParamSource, TypeString, args[ParamSource])
+		// 	err = expr.ErrWrongParamType(name, expr.ParamSource, expr.TypeString, args[expr.ParamSource])
 		// }
 	} else if result, ok = ctx.GetVar(varName); !ok {
-		err = ErrUnknownVar(name, varName)
+		err = kern.ErrUnknownVar(name, varName)
 	}
 	return
 }
 
-func setFunc(ctx ExprContext, name string, args map[string]any) (result any, err error) {
+func setFunc(ctx kern.ExprContext, name string, args map[string]any) (result any, err error) {
 	var varName string
 	var ok bool
 
-	if varName, ok = args[ParamName].(string); !ok {
-		return nil, ErrWrongParamType(name, ParamName, TypeString, args[ParamName])
+	if varName, ok = args[kern.ParamName].(string); !ok {
+		return nil, kern.ErrWrongParamType(name, kern.ParamName, kern.TypeString, args[kern.ParamName])
 	}
 
-	if result, ok = args[ParamValue]; ok {
+	if result, ok = args[kern.ParamValue]; ok {
 		ctx.GetParent().UnsafeSetVar(varName, result)
 	} else {
-		err = ErrWrongParamType(name, ParamValue, TypeAny, args[ParamValue])
+		err = kern.ErrWrongParamType(name, kern.ParamValue, kern.TypeAny, args[kern.ParamValue])
 	}
 	return
 }
 
-func unsetFunc(ctx ExprContext, name string, args map[string]any) (result any, err error) {
+func unsetFunc(ctx kern.ExprContext, name string, args map[string]any) (result any, err error) {
 	var varName string
 	var ok bool
 
-	if varName, ok = args[ParamName].(string); !ok {
-		return nil, ErrWrongParamType(name, ParamName, TypeString, args[ParamName])
+	if varName, ok = args[kern.ParamName].(string); !ok {
+		return nil, kern.ErrWrongParamType(name, kern.ParamName, kern.TypeString, args[kern.ParamName])
 	} else {
 		ctx.GetParent().DeleteVar(varName)
 		result = nil
@@ -267,47 +269,47 @@ func unsetFunc(ctx ExprContext, name string, args map[string]any) (result any, e
 
 //// import
 
-func ImportBuiltinsFuncs(ctx ExprContext) {
-	anyParams := []ExprFuncParam{
-		NewFuncParam(ParamValue),
+func ImportBuiltinsFuncs(ctx kern.ExprContext) {
+	anyParams := []kern.ExprFuncParam{
+		NewFuncParam(kern.ParamValue),
 	}
 
-	ctx.RegisterFunc("isNil", NewGolangFunctor(isNilFunc), TypeBoolean, anyParams)
-	ctx.RegisterFunc("isInt", NewGolangFunctor(isIntFunc), TypeBoolean, anyParams)
-	ctx.RegisterFunc("isFloat", NewGolangFunctor(isFloatFunc), TypeBoolean, anyParams)
-	ctx.RegisterFunc("isBool", NewGolangFunctor(isBoolFunc), TypeBoolean, anyParams)
-	ctx.RegisterFunc("isString", NewGolangFunctor(isStringFunc), TypeBoolean, anyParams)
-	ctx.RegisterFunc("isFract", NewGolangFunctor(isFractionFunc), TypeBoolean, anyParams)
-	ctx.RegisterFunc("isRational", NewGolangFunctor(isRationalFunc), TypeBoolean, anyParams)
-	ctx.RegisterFunc("isList", NewGolangFunctor(isListFunc), TypeBoolean, anyParams)
-	ctx.RegisterFunc("isDict", NewGolangFunctor(isDictionaryFunc), TypeBoolean, anyParams)
+	ctx.RegisterFunc("isNil", kern.NewGolangFunctor(isNilFunc), kern.TypeBoolean, anyParams)
+	ctx.RegisterFunc("isInt", kern.NewGolangFunctor(isIntFunc), kern.TypeBoolean, anyParams)
+	ctx.RegisterFunc("isFloat", kern.NewGolangFunctor(isFloatFunc), kern.TypeBoolean, anyParams)
+	ctx.RegisterFunc("isBool", kern.NewGolangFunctor(isBoolFunc), kern.TypeBoolean, anyParams)
+	ctx.RegisterFunc("isString", kern.NewGolangFunctor(isStringFunc), kern.TypeBoolean, anyParams)
+	ctx.RegisterFunc("isFract", kern.NewGolangFunctor(isFractionFunc), kern.TypeBoolean, anyParams)
+	ctx.RegisterFunc("isRational", kern.NewGolangFunctor(isRationalFunc), kern.TypeBoolean, anyParams)
+	ctx.RegisterFunc("isList", kern.NewGolangFunctor(isListFunc), kern.TypeBoolean, anyParams)
+	ctx.RegisterFunc("isDict", kern.NewGolangFunctor(isDictionaryFunc), kern.TypeBoolean, anyParams)
 
-	ctx.RegisterFunc("bool", NewGolangFunctor(boolFunc), TypeBoolean, anyParams)
-	ctx.RegisterFunc("int", NewGolangFunctor(intFunc), TypeInt, anyParams)
-	ctx.RegisterFunc("dec", NewGolangFunctor(decFunc), TypeFloat, anyParams)
-	ctx.RegisterFunc("string", NewGolangFunctor(stringFunc), TypeString, anyParams)
-	ctx.RegisterFunc("fract", NewGolangFunctor(fractFunc), TypeFraction, []ExprFuncParam{
-		NewFuncParam(ParamValue),
+	ctx.RegisterFunc("bool", kern.NewGolangFunctor(boolFunc), kern.TypeBoolean, anyParams)
+	ctx.RegisterFunc("int", kern.NewGolangFunctor(intFunc), kern.TypeInt, anyParams)
+	ctx.RegisterFunc("dec", kern.NewGolangFunctor(decFunc), kern.TypeFloat, anyParams)
+	ctx.RegisterFunc("string", kern.NewGolangFunctor(stringFunc), kern.TypeString, anyParams)
+	ctx.RegisterFunc("fract", kern.NewGolangFunctor(fractFunc), kern.TypeFraction, []kern.ExprFuncParam{
+		NewFuncParam(kern.ParamValue),
 		NewFuncParamFlagDef(ParamDenominator, PfDefault, int64(1)),
 	})
 
-	ctx.RegisterFunc("eval", NewGolangFunctor(evalFunc), TypeAny, []ExprFuncParam{
-		NewFuncParam(ParamSource),
+	ctx.RegisterFunc("eval", kern.NewGolangFunctor(evalFunc), kern.TypeAny, []kern.ExprFuncParam{
+		NewFuncParam(kern.ParamSource),
 	})
 
-	ctx.RegisterFunc("var", NewGolangFunctor(varFunc), TypeAny, []ExprFuncParam{
-		NewFuncParam(ParamName),
-		NewFuncParamFlagDef(ParamValue, PfDefault, nil),
+	ctx.RegisterFunc("var", kern.NewGolangFunctor(varFunc), kern.TypeAny, []kern.ExprFuncParam{
+		NewFuncParam(kern.ParamName),
+		NewFuncParamFlagDef(kern.ParamValue, PfDefault, nil),
 	})
 
-	ctx.RegisterFunc("set", NewGolangFunctor(setFunc), TypeAny, []ExprFuncParam{
-		NewFuncParam(ParamName),
-		NewFuncParam(ParamValue),
+	ctx.RegisterFunc("set", kern.NewGolangFunctor(setFunc), kern.TypeAny, []kern.ExprFuncParam{
+		NewFuncParam(kern.ParamName),
+		NewFuncParam(kern.ParamValue),
 	})
 
-	ctx.RegisterFunc("unset", NewGolangFunctor(unsetFunc), TypeAny, []ExprFuncParam{
-		NewFuncParam(ParamName),
-		NewFuncParam(ParamValue),
+	ctx.RegisterFunc("unset", kern.NewGolangFunctor(unsetFunc), kern.TypeAny, []kern.ExprFuncParam{
+		NewFuncParam(kern.ParamName),
+		NewFuncParam(kern.ParamValue),
 	})
 }
 

builtin-fmt.go

@@ -8,11 +8,13 @@ import (
 	"fmt"
 	"io"
 	"os"
+
+	"git.portale-stac.it/go-pkg/expr/kern"
 )
 
-func getStdout(ctx ExprContext) io.Writer {
+func getStdout(ctx kern.ExprContext) io.Writer {
 	var w io.Writer
-	if wany, exists := ctx.GetVar(ControlStdout); exists && wany != nil {
+	if wany, exists := ctx.GetVar(kern.ControlStdout); exists && wany != nil {
 		w, _ = wany.(io.Writer)
 	}
 	if w == nil {
@@ -21,9 +23,9 @@ func getStdout(ctx ExprContext) io.Writer {
 	return w
 }
 
-func printFunc(ctx ExprContext, name string, args map[string]any) (result any, err error) {
+func printFunc(ctx kern.ExprContext, name string, args map[string]any) (result any, err error) {
 	var n int = 0
-	if v, exists := args[ParamItem]; exists && v != nil {
+	if v, exists := args[kern.ParamItem]; exists && v != nil {
 		argv := v.([]any)
 		n, err = fmt.Fprint(getStdout(ctx), argv...)
 	}
@@ -31,9 +33,9 @@ func printFunc(ctx ExprContext, name string, args map[string]any) (result any, e
 	return
 }
 
-func printLnFunc(ctx ExprContext, name string, args map[string]any) (result any, err error) {
+func printLnFunc(ctx kern.ExprContext, name string, args map[string]any) (result any, err error) {
 	var n int = 0
-	if v, exists := args[ParamItem]; exists && v != nil {
+	if v, exists := args[kern.ParamItem]; exists && v != nil {
 		argv := v.([]any)
 		n, err = fmt.Fprintln(getStdout(ctx), argv...)
 	} else {
@@ -43,12 +45,12 @@ func printLnFunc(ctx ExprContext, name string, args map[string]any) (result any,
 	return
 }
 
-func ImportFmtFuncs(ctx ExprContext) {
-	ctx.RegisterFunc("print", NewGolangFunctor(printFunc), TypeInt, []ExprFuncParam{
-		NewFuncParamFlag(ParamItem, PfRepeat),
+func ImportFmtFuncs(ctx kern.ExprContext) {
+	ctx.RegisterFunc("print", kern.NewGolangFunctor(printFunc), kern.TypeInt, []kern.ExprFuncParam{
+		NewFuncParamFlag(kern.ParamItem, PfRepeat),
 	})
-	ctx.RegisterFunc("println", NewGolangFunctor(printLnFunc), TypeInt, []ExprFuncParam{
-		NewFuncParamFlag(ParamItem, PfRepeat),
+	ctx.RegisterFunc("println", kern.NewGolangFunctor(printLnFunc), kern.TypeInt, []kern.ExprFuncParam{
+		NewFuncParamFlag(kern.ParamItem, PfRepeat),
 	})
 }
 

builtin-import.go

@@ -7,32 +7,34 @@ package expr
 import (
 	"io"
 	"os"
+
+	"git.portale-stac.it/go-pkg/expr/kern"
 )
 
-func importFunc(ctx ExprContext, name string, args map[string]any) (result any, err error) {
+func importFunc(ctx kern.ExprContext, name string, args map[string]any) (result any, err error) {
 	return importGeneral(ctx, name, args)
 }
 
-func importAllFunc(ctx ExprContext, name string, args map[string]any) (result any, err error) {
-	CtrlEnable(ctx, control_export_all)
+func importAllFunc(ctx kern.ExprContext, name string, args map[string]any) (result any, err error) {
+	CtrlEnable(ctx, kern.ControlExportAll)
 	return importGeneral(ctx, name, args)
 }
 
-func importGeneral(ctx ExprContext, name string, args map[string]any) (result any, err error) {
-	dirList := buildSearchDirList("sources", ENV_EXPR_SOURCE_PATH)
-	if v, exists := args[ParamFilepath]; exists && v != nil {
+func importGeneral(ctx kern.ExprContext, name string, args map[string]any) (result any, err error) {
+	dirList := buildSearchDirList(ctx, "sources", ENV_EXPR_SOURCE_PATH)
+	if v, exists := args[kern.ParamFilepath]; exists && v != nil {
 		argv := v.([]any)
 		result, err = doImport(ctx, name, dirList, NewArrayIterator(argv))
 	}
 	return
 }
 
-func doImport(ctx ExprContext, name string, dirList []string, it Iterator) (result any, err error) {
+func doImport(ctx kern.ExprContext, name string, dirList []string, it kern.Iterator) (result any, err error) {
 	var v any
 	var sourceFilepath string
 
 	for v, err = it.Next(); err == nil; v, err = it.Next() {
-		if err = checkStringParamExpected(name, v, it.Index()); err != nil {
+		if err = checkStringParamExpected(name, v, int(it.Index())); err != nil {
 			break
 		}
 		if sourceFilepath, err = makeFilepath(v.(string), dirList); err != nil {
@@ -64,12 +66,12 @@ func doImport(ctx ExprContext, name string, dirList []string, it Iterator) (resu
 	return
 }
 
-func ImportImportFuncs(ctx ExprContext) {
-	ctx.RegisterFunc("import", NewGolangFunctor(importFunc), TypeAny, []ExprFuncParam{
-		NewFuncParamFlag(ParamFilepath, PfRepeat),
+func ImportImportFuncs(ctx kern.ExprContext) {
+	ctx.RegisterFunc("import", kern.NewGolangFunctor(importFunc), kern.TypeAny, []kern.ExprFuncParam{
+		NewFuncParamFlag(kern.ParamFilepath, PfRepeat),
 	})
-	ctx.RegisterFunc("importAll", NewGolangFunctor(importAllFunc), TypeAny, []ExprFuncParam{
-		NewFuncParamFlag(ParamFilepath, PfRepeat),
+	ctx.RegisterFunc("importAll", kern.NewGolangFunctor(importAllFunc), kern.TypeAny, []kern.ExprFuncParam{
+		NewFuncParamFlag(kern.ParamFilepath, PfRepeat),
 	})
 }
 

builtin-iterator.go

@@ -7,6 +7,8 @@ package expr
 import (
 	"fmt"
 	"io"
+
+	"git.portale-stac.it/go-pkg/expr/kern"
 )
 
 const (
@@ -15,24 +17,24 @@ const (
 	iterVarStatus     = "status"
 )
 
-func parseRunArgs(localCtx ExprContext, args map[string]any) (it Iterator, op Functor, err error) {
+func parseRunArgs(localCtx kern.ExprContext, args map[string]any) (it kern.Iterator, op kern.Functor, err error) {
 	var ok bool
 
-	if it, ok = args[ParamIterator].(Iterator); !ok {
-		err = fmt.Errorf("paramter %q must be an iterator, passed %v [%s]", ParamIterator, args[ParamIterator], TypeName(args[ParamIterator]))
+	if it, ok = args[kern.ParamIterator].(kern.Iterator); !ok {
+		err = fmt.Errorf("paramter %q must be an iterator, passed %v [%s]", kern.ParamIterator, args[kern.ParamIterator], kern.TypeName(args[kern.ParamIterator]))
 		return
 	}
 
 	if args[iterParamOperator] != nil {
-		if op, ok = args[iterParamOperator].(Functor); !ok || op == nil {
-			err = fmt.Errorf("paramter %q must be a function, passed %v [%s]", iterParamOperator, args[iterParamOperator], TypeName(args[iterParamOperator]))
+		if op, ok = args[iterParamOperator].(kern.Functor); !ok || op == nil {
+			err = fmt.Errorf("paramter %q must be a function, passed %v [%s]", iterParamOperator, args[iterParamOperator], kern.TypeName(args[iterParamOperator]))
 			return
 		}
 	}
 
-	var vars *DictType
-	if vars, ok = args[iterParamVars].(*DictType); !ok && args[iterParamVars] != nil {
-		err = fmt.Errorf("paramter %q must be a dictionary, passed %v [%s]", iterParamVars, args[iterParamVars], TypeName(args[iterParamVars]))
+	var vars *kern.DictType
+	if vars, ok = args[iterParamVars].(*kern.DictType); !ok && args[iterParamVars] != nil {
+		err = fmt.Errorf("paramter %q must be a dictionary, passed %v [%s]", iterParamVars, args[iterParamVars], kern.TypeName(args[iterParamVars]))
 		return
 	}
 
@@ -48,10 +50,10 @@ func parseRunArgs(localCtx ExprContext, args map[string]any) (it Iterator, op Fu
 	return
 }
 
-func runFunc(ctx ExprContext, name string, args map[string]any) (result any, err error) {
-	var it Iterator
+func runFunc(ctx kern.ExprContext, name string, args map[string]any) (result any, err error) {
+	var it kern.Iterator
 	var ok bool
-	var op Functor
+	var op kern.Functor
 	var v any
 	// var usingDefaultOp = false
 	var params map[string]any
@@ -62,25 +64,16 @@ func runFunc(ctx ExprContext, name string, args map[string]any) (result any, err
 
 	if it, op, err = parseRunArgs(localCtx, args); err != nil {
 		return
-		// } else if op == nil {
-		// 	op = NewGolangFunctor(printLnFunc)
-		// 	usingDefaultOp = true
 	}
 
 	for item, err = it.Next(); err == nil; item, err = it.Next() {
-		// if usingDefaultOp {
-		// 	params = map[string]any{ParamItem: []any{item}}
-		// } else {
-		// params = map[string]any{ParamIndex: it.Index(), ParamItem: item}
-		// }
-
 		if op != nil {
-			params = map[string]any{ParamIndex: it.Index(), ParamItem: item}
+			params = map[string]any{kern.ParamIndex: it.Index(), kern.ParamItem: item}
 			if v, err = op.InvokeNamed(localCtx, iterParamOperator, params); err != nil {
 				break
 			} else {
 				var success bool
-				if success, ok = ToBool(v); !success || !ok {
+				if success, ok = kern.ToBool(v); !success || !ok {
 					break
 				}
 			}
@@ -99,9 +92,9 @@ func runFunc(ctx ExprContext, name string, args map[string]any) (result any, err
 	return
 }
 
-func ImportIterFuncs(ctx ExprContext) {
-	ctx.RegisterFunc("run", NewGolangFunctor(runFunc), TypeAny, []ExprFuncParam{
-		NewFuncParam(ParamIterator),
+func ImportIterFuncs(ctx kern.ExprContext) {
+	ctx.RegisterFunc("run", kern.NewGolangFunctor(runFunc), kern.TypeAny, []kern.ExprFuncParam{
+		NewFuncParam(kern.ParamIterator),
 		NewFuncParamFlag(iterParamOperator, PfOptional),
 		NewFuncParamFlag(iterParamVars, PfOptional),
 	})

builtin-math-arith.go

@@ -7,67 +7,69 @@ package expr
 import (
 	"fmt"
 	"io"
+
+	"git.portale-stac.it/go-pkg/expr/kern"
 )
 
 func checkNumberParamExpected(funcName string, paramValue any, paramPos, level, subPos int) (err error) {
-	if !(IsNumber(paramValue) || isFraction(paramValue)) /*|| isList(paramValue)*/ {
+	if !(kern.IsNumber(paramValue) || kern.IsFraction(paramValue)) /*|| isList(paramValue)*/ {
 		err = fmt.Errorf("%s(): param nr %d (%d in %d) has wrong type %T, number expected",
 			funcName, paramPos+1, subPos+1, level, paramValue)
 	}
 	return
 }
 
-func doAdd(ctx ExprContext, name string, it Iterator, count, level int) (result any, err error) {
+func doAdd(ctx kern.ExprContext, name string, it kern.Iterator, count, level int) (result any, err error) {
 	var sumAsFloat, sumAsFract bool
 	var floatSum float64 = 0.0
 	var intSum int64 = 0
-	var fractSum *FractionType
+	var fractSum *kern.FractionType
 	var v any
 
 	level++
 
 	for v, err = it.Next(); err == nil; v, err = it.Next() {
-		if list, ok := v.(*ListType); ok {
+		if list, ok := v.(*kern.ListType); ok {
 			v = NewListIterator(list, nil)
 		}
-		if subIter, ok := v.(Iterator); ok {
+		if subIter, ok := v.(kern.Iterator); ok {
 			if v, err = doAdd(ctx, name, subIter, count, level); err != nil {
 				break
 			}
-			if extIter, ok := v.(ExtIterator); ok && extIter.HasOperation(CleanName) {
-				if _, err = extIter.CallOperation(CleanName, nil); err != nil {
+			if extIter, ok := v.(kern.ExtIterator); ok && extIter.HasOperation(kern.CleanName) {
+				if _, err = extIter.CallOperation(kern.CleanName, nil); err != nil {
 					return
 				}
 			}
-		} else if err = checkNumberParamExpected(name, v, count, level, it.Index()); err != nil {
+		} else if err = checkNumberParamExpected(name, v, count, level, int(it.Index())); err != nil {
 			break
 		}
 		count++
 
 		if !sumAsFloat {
-			if IsFloat(v) {
+			if kern.IsFloat(v) {
 				sumAsFloat = true
 				if sumAsFract {
-					floatSum = fractSum.toFloat()
+					floatSum = fractSum.ToFloat()
 				} else {
 					floatSum = float64(intSum)
 				}
-			} else if !sumAsFract && isFraction(v) {
-				fractSum = newFraction(intSum, 1)
+			} else if !sumAsFract && kern.IsFraction(v) {
+				fractSum = kern.NewFraction(intSum, 1)
 				sumAsFract = true
 			}
 		}
 
 		if sumAsFloat {
-			floatSum += numAsFloat(v)
+			floatSum += kern.NumAsFloat(v)
 		} else if sumAsFract {
-			var item *FractionType
+			var item *kern.FractionType
 			var ok bool
-			if item, ok = v.(*FractionType); !ok {
+			if item, ok = v.(*kern.FractionType); !ok {
 				iv, _ := v.(int64)
-				item = newFraction(iv, 1)
+				item = kern.NewFraction(iv, 1)
 			}
-			fractSum = sumFract(fractSum, item)
+			fractSum = kern.SumFract(fractSum, item)
 		} else {
 			iv, _ := v.(int64)
 			intSum += iv
@@ -86,64 +88,64 @@ func doAdd(ctx ExprContext, name string, it Iterator, count, level int) (result
 	return
 }
 
-func addFunc(ctx ExprContext, name string, args map[string]any) (result any, err error) {
-	argv := args[ParamValue].([]any)
+func addFunc(ctx kern.ExprContext, name string, args map[string]any) (result any, err error) {
+	argv := args[kern.ParamValue].([]any)
 	result, err = doAdd(ctx, name, NewArrayIterator(argv), 0, -1)
 	return
 }
 
-func doMul(ctx ExprContext, name string, it Iterator, count, level int) (result any, err error) {
+func doMul(ctx kern.ExprContext, name string, it kern.Iterator, count, level int) (result any, err error) {
 	var mulAsFloat, mulAsFract bool
 	var floatProd float64 = 1.0
 	var intProd int64 = 1
-	var fractProd *FractionType
+	var fractProd *kern.FractionType
 	var v any
 
 	level++
 	for v, err = it.Next(); err == nil; v, err = it.Next() {
-		if list, ok := v.(*ListType); ok {
+		if list, ok := v.(*kern.ListType); ok {
 			v = NewListIterator(list, nil)
 		}
-		if subIter, ok := v.(Iterator); ok {
+		if subIter, ok := v.(kern.Iterator); ok {
 			if v, err = doMul(ctx, name, subIter, count, level); err != nil {
 				break
 			}
-			if extIter, ok := v.(ExtIterator); ok && extIter.HasOperation(CleanName) {
-				if _, err = extIter.CallOperation(CleanName, nil); err != nil {
+			if extIter, ok := v.(kern.ExtIterator); ok && extIter.HasOperation(kern.CleanName) {
+				if _, err = extIter.CallOperation(kern.CleanName, nil); err != nil {
 					return
 				}
 			}
 		} else {
-			if err = checkNumberParamExpected(name, v, count, level, it.Index()); err != nil {
+			if err = checkNumberParamExpected(name, v, count, level, int(it.Index())); err != nil {
 				break
 			}
 		}
 		count++
 
 		if !mulAsFloat {
-			if IsFloat(v) {
+			if kern.IsFloat(v) {
 				mulAsFloat = true
 				if mulAsFract {
-					floatProd = fractProd.toFloat()
+					floatProd = fractProd.ToFloat()
 				} else {
 					floatProd = float64(intProd)
 				}
-			} else if !mulAsFract && isFraction(v) {
-				fractProd = newFraction(intProd, 1)
+			} else if !mulAsFract && kern.IsFraction(v) {
+				fractProd = kern.NewFraction(intProd, 1)
 				mulAsFract = true
 			}
 		}
 
 		if mulAsFloat {
-			floatProd *= numAsFloat(v)
+			floatProd *= kern.NumAsFloat(v)
 		} else if mulAsFract {
-			var item *FractionType
+			var item *kern.FractionType
 			var ok bool
-			if item, ok = v.(*FractionType); !ok {
+			if item, ok = v.(*kern.FractionType); !ok {
 				iv, _ := v.(int64)
-				item = newFraction(iv, 1)
+				item = kern.NewFraction(iv, 1)
 			}
-			fractProd = mulFract(fractProd, item)
+			fractProd = kern.MulFract(fractProd, item)
 		} else {
 			iv, _ := v.(int64)
 			intProd *= iv
@@ -162,19 +164,19 @@ func doMul(ctx ExprContext, name string, it Iterator, count, level int) (result
 	return
 }
 
-func mulFunc(ctx ExprContext, name string, args map[string]any) (result any, err error) {
-	argv := args[ParamValue].([]any)
+func mulFunc(ctx kern.ExprContext, name string, args map[string]any) (result any, err error) {
+	argv := args[kern.ParamValue].([]any)
 	result, err = doMul(ctx, name, NewArrayIterator(argv), 0, -1)
 	return
 }
 
-func ImportMathFuncs(ctx ExprContext) {
-	ctx.RegisterFunc("add", NewGolangFunctor(addFunc), TypeNumber, []ExprFuncParam{
-		NewFuncParamFlagDef(ParamValue, PfDefault|PfRepeat, int64(0)),
+func ImportMathFuncs(ctx kern.ExprContext) {
+	ctx.RegisterFunc("add", kern.NewGolangFunctor(addFunc), kern.TypeNumber, []kern.ExprFuncParam{
+		NewFuncParamFlagDef(kern.ParamValue, PfDefault|PfRepeat, int64(0)),
 	})
 
-	ctx.RegisterFunc("mul", NewGolangFunctor(mulFunc), TypeNumber, []ExprFuncParam{
-		NewFuncParamFlagDef(ParamValue, PfDefault|PfRepeat, int64(1)),
+	ctx.RegisterFunc("mul", kern.NewGolangFunctor(mulFunc), kern.TypeNumber, []kern.ExprFuncParam{
+		NewFuncParamFlagDef(kern.ParamValue, PfDefault|PfRepeat, int64(1)),
 	})
 }
 

builtin-os-file-iter.go

@@ -8,6 +8,8 @@ import (
 	"fmt"
 	"io"
 	"slices"
+
+	"git.portale-stac.it/go-pkg/expr/kern"
 )
 
 const paramHandleOrPath = "handle-or-path"
@@ -15,8 +17,8 @@ const fileReadTextIteratorType = "fileReadTextIterator"
 
 type fileReadTextIterator struct {
 	osReader  *osReader
-	index     int
-	count     int
+	index     int64
+	count     int64
 	line      string
 	autoClose bool
 }
@@ -36,7 +38,7 @@ func (it *fileReadTextIterator) String() string {
 	return fmt.Sprintf("$(%s@<nil>)", fileReadTextIteratorType)
 }
 
-func (it *fileReadTextIterator) Count() int {
+func (it *fileReadTextIterator) Count() int64 {
 	return it.count
 }
 
@@ -60,7 +62,7 @@ func (it *fileReadTextIterator) Current() (item any, err error) {
 	return
 }
 
-func (it *fileReadTextIterator) Index() int {
+func (it *fileReadTextIterator) Index() int64 {
 	return it.index
 }
 
@@ -74,7 +76,7 @@ func (it *fileReadTextIterator) Reset() (err error) {
 }
 
 func (it *fileReadTextIterator) HasOperation(name string) bool {
-	return slices.Contains([]string{NextName, ResetName, IndexName, CountName, CurrentName, CleanName}, name)
+	return slices.Contains([]string{kern.NextName, kern.ResetName, kern.IndexName, kern.CountName, kern.CurrentName, kern.CleanName}, name)
 }
 
 func (it *fileReadTextIterator) Clean() (err error) {
@@ -88,25 +90,25 @@ func (it *fileReadTextIterator) Clean() (err error) {
 
 func (it *fileReadTextIterator) CallOperation(name string, args map[string]any) (v any, err error) {
 	switch name {
-	case NextName:
+	case kern.NextName:
 		v, err = it.Next()
-	case ResetName:
+	case kern.ResetName:
 		err = it.Reset()
-	case CleanName:
+	case kern.CleanName:
 		err = it.Clean()
-	case IndexName:
+	case kern.IndexName:
 		v = int64(it.Index())
-	case CurrentName:
+	case kern.CurrentName:
 		v, err = it.Current()
-	case CountName:
+	case kern.CountName:
 		v = it.count
 	default:
-		err = errNoOperation(name)
+		err = kern.ErrNoOperation(name)
 	}
 	return
 }
 
-func fileReadIteratorFunc(ctx ExprContext, name string, args map[string]any) (result any, err error) {
+func fileReadIteratorFunc(ctx kern.ExprContext, name string, args map[string]any) (result any, err error) {
 	var handle *osReader
 	var invalidFileHandle any
 	var ok, autoClose bool
@@ -115,7 +117,7 @@ func fileReadIteratorFunc(ctx ExprContext, name string, args map[string]any) (re
 	if handle, ok = args[paramHandleOrPath].(*osReader); !ok {
 		if fileName, ok := args[paramHandleOrPath].(string); ok && len(fileName) > 0 {
 			var handleAny any
-			if handleAny, err = openFileFunc(ctx, name, map[string]any{ParamFilepath: fileName}); err != nil {
+			if handleAny, err = openFileFunc(ctx, name, map[string]any{kern.ParamFilepath: fileName}); err != nil {
 				return
 			}
 			if handleAny != nil {

builtin-os-file.go

@@ -9,6 +9,8 @@ import (
 	"fmt"
 	"io"
 	"os"
+
+	"git.portale-stac.it/go-pkg/expr/kern"
 )
 
 const (
@@ -65,8 +67,8 @@ func errInvalidFileHandle(funcName string, v any) error {
 	}
 }
 
-func createFileFunc(ctx ExprContext, name string, args map[string]any) (result any, err error) {
-	if filePath, ok := args[ParamFilepath].(string); ok && len(filePath) > 0 {
+func createFileFunc(ctx kern.ExprContext, name string, args map[string]any) (result any, err error) {
+	if filePath, ok := args[kern.ParamFilepath].(string); ok && len(filePath) > 0 {
 		var fh *os.File
 		if fh, err = os.Create(filePath); err == nil {
 			result = &osWriter{fh: fh, writer: bufio.NewWriter(fh)}
@@ -77,8 +79,8 @@ func createFileFunc(ctx ExprContext, name string, args map[string]any) (result a
 	return
 }
 
-func openFileFunc(ctx ExprContext, name string, args map[string]any) (result any, err error) {
-	if filePath, ok := args[ParamFilepath].(string); ok && len(filePath) > 0 {
+func openFileFunc(ctx kern.ExprContext, name string, args map[string]any) (result any, err error) {
+	if filePath, ok := args[kern.ParamFilepath].(string); ok && len(filePath) > 0 {
 		var fh *os.File
 		if fh, err = os.Open(filePath); err == nil {
 			result = &osReader{fh: fh, reader: bufio.NewReader(fh)}
@@ -89,8 +91,8 @@ func openFileFunc(ctx ExprContext, name string, args map[string]any) (result any
 	return
 }
 
-func appendFileFunc(ctx ExprContext, name string, args map[string]any) (result any, err error) {
-	if filePath, ok := args[ParamFilepath].(string); ok && len(filePath) > 0 {
+func appendFileFunc(ctx kern.ExprContext, name string, args map[string]any) (result any, err error) {
+	if filePath, ok := args[kern.ParamFilepath].(string); ok && len(filePath) > 0 {
 		var fh *os.File
 		if fh, err = os.OpenFile(filePath, os.O_APPEND|os.O_WRONLY|os.O_CREATE, 0660); err == nil {
 			result = &osWriter{fh: fh, writer: bufio.NewWriter(fh)}
@@ -101,13 +103,13 @@ func appendFileFunc(ctx ExprContext, name string, args map[string]any) (result a
 	return
 }
 
-func closeFileFunc(ctx ExprContext, name string, args map[string]any) (result any, err error) {
+func closeFileFunc(ctx kern.ExprContext, name string, args map[string]any) (result any, err error) {
 	var handle osHandle
 	var invalidFileHandle any
 	var ok bool
 
-	if handle, ok = args[ParamHandle].(osHandle); !ok {
-		invalidFileHandle = args[ParamHandle]
+	if handle, ok = args[kern.ParamHandle].(osHandle); !ok {
+		invalidFileHandle = args[kern.ParamHandle]
 	}
 
 	if handle != nil {
@@ -128,18 +130,18 @@ func closeFileFunc(ctx ExprContext, name string, args map[string]any) (result an
 	return
 }
 
-func fileWriteTextFunc(ctx ExprContext, name string, args map[string]any) (result any, err error) {
+func fileWriteTextFunc(ctx kern.ExprContext, name string, args map[string]any) (result any, err error) {
 	var handle osHandle
 	var invalidFileHandle any
 	var ok bool
 
-	if handle, ok = args[ParamHandle].(osHandle); !ok {
-		invalidFileHandle = args[ParamHandle]
+	if handle, ok = args[kern.ParamHandle].(osHandle); !ok {
+		invalidFileHandle = args[kern.ParamHandle]
 	}
 
 	if handle != nil {
 		if w, ok := handle.(*osWriter); ok {
-			if v, exists := args[ParamItem]; exists {
+			if v, exists := args[kern.ParamItem]; exists {
 				argv := v.([]any)
 				result, err = fmt.Fprint(w.writer, argv...)
 			}
@@ -154,14 +156,14 @@ func fileWriteTextFunc(ctx ExprContext, name string, args map[string]any) (resul
 	return
 }
 
-func fileReadTextFunc(ctx ExprContext, name string, args map[string]any) (result any, err error) {
+func fileReadTextFunc(ctx kern.ExprContext, name string, args map[string]any) (result any, err error) {
 	var handle osHandle
 	var invalidFileHandle any
 	var ok bool
 
 	result = nil
-	if handle, ok = args[ParamHandle].(osHandle); !ok || args[ParamHandle] == nil {
-		invalidFileHandle = args[ParamHandle]
+	if handle, ok = args[kern.ParamHandle].(osHandle); !ok || args[kern.ParamHandle] == nil {
+		invalidFileHandle = args[kern.ParamHandle]
 	}
 
 	if handle != nil {
@@ -194,14 +196,14 @@ func fileReadTextFunc(ctx ExprContext, name string, args map[string]any) (result
 	return
 }
 
-func fileReadTextAllFunc(ctx ExprContext, name string, args map[string]any) (result any, err error) {
+func fileReadTextAllFunc(ctx kern.ExprContext, name string, args map[string]any) (result any, err error) {
 	var handle osHandle
 	var invalidFileHandle any
 	var ok bool
 
 	result = nil
-	if handle, ok = args[ParamHandle].(osHandle); !ok || args[ParamHandle] == nil {
-		invalidFileHandle = args[ParamHandle]
+	if handle, ok = args[kern.ParamHandle].(osHandle); !ok || args[kern.ParamHandle] == nil {
+		invalidFileHandle = args[kern.ParamHandle]
 	}
 
 	if handle != nil {
@@ -220,38 +222,38 @@ func fileReadTextAllFunc(ctx ExprContext, name string, args map[string]any) (res
 	return
 }
 
-func ImportOsFuncs(ctx ExprContext) {
-	ctx.RegisterFunc("fileOpen", NewGolangFunctor(openFileFunc), TypeFileHandle, []ExprFuncParam{
-		NewFuncParam(ParamFilepath),
+func ImportOsFuncs(ctx kern.ExprContext) {
+	ctx.RegisterFunc("fileOpen", kern.NewGolangFunctor(openFileFunc), kern.TypeFileHandle, []kern.ExprFuncParam{
+		NewFuncParam(kern.ParamFilepath),
 	})
 
-	ctx.RegisterFunc("fileAppend", NewGolangFunctor(appendFileFunc), TypeFileHandle, []ExprFuncParam{
-		NewFuncParam(ParamFilepath),
+	ctx.RegisterFunc("fileAppend", kern.NewGolangFunctor(appendFileFunc), kern.TypeFileHandle, []kern.ExprFuncParam{
+		NewFuncParam(kern.ParamFilepath),
 	})
 
-	ctx.RegisterFunc("fileCreate", NewGolangFunctor(createFileFunc), TypeFileHandle, []ExprFuncParam{
-		NewFuncParam(ParamFilepath),
+	ctx.RegisterFunc("fileCreate", kern.NewGolangFunctor(createFileFunc), kern.TypeFileHandle, []kern.ExprFuncParam{
+		NewFuncParam(kern.ParamFilepath),
 	})
 
-	ctx.RegisterFunc("fileClose", NewGolangFunctor(closeFileFunc), TypeBoolean, []ExprFuncParam{
-		NewFuncParam(ParamHandle),
+	ctx.RegisterFunc("fileClose", kern.NewGolangFunctor(closeFileFunc), kern.TypeBoolean, []kern.ExprFuncParam{
+		NewFuncParam(kern.ParamHandle),
 	})
 
-	ctx.RegisterFunc("fileWriteText", NewGolangFunctor(fileWriteTextFunc), TypeInt, []ExprFuncParam{
-		NewFuncParam(ParamHandle),
-		NewFuncParamFlagDef(ParamItem, PfDefault|PfRepeat, ""),
+	ctx.RegisterFunc("fileWriteText", kern.NewGolangFunctor(fileWriteTextFunc), kern.TypeInt, []kern.ExprFuncParam{
+		NewFuncParam(kern.ParamHandle),
+		NewFuncParamFlagDef(kern.ParamItem, PfDefault|PfRepeat, ""),
 	})
 
-	ctx.RegisterFunc("fileReadText", NewGolangFunctor(fileReadTextFunc), TypeString, []ExprFuncParam{
-		NewFuncParam(ParamHandle),
+	ctx.RegisterFunc("fileReadText", kern.NewGolangFunctor(fileReadTextFunc), kern.TypeString, []kern.ExprFuncParam{
+		NewFuncParam(kern.ParamHandle),
 		NewFuncParamFlagDef(osLimitCh, PfDefault, "\n"),
 	})
 
-	ctx.RegisterFunc("fileReadTextAll", NewGolangFunctor(fileReadTextAllFunc), TypeString, []ExprFuncParam{
-		NewFuncParam(ParamHandle),
+	ctx.RegisterFunc("fileReadTextAll", kern.NewGolangFunctor(fileReadTextAllFunc), kern.TypeString, []kern.ExprFuncParam{
+		NewFuncParam(kern.ParamHandle),
 	})
 
-	ctx.RegisterFunc("fileReadIterator", NewGolangFunctor(fileReadIteratorFunc), TypeIterator, []ExprFuncParam{
+	ctx.RegisterFunc("fileReadIterator", kern.NewGolangFunctor(fileReadIteratorFunc), kern.TypeIterator, []kern.ExprFuncParam{
 		NewFuncParam(paramHandleOrPath),
 	})
 }

builtin-string.go

@@ -8,6 +8,8 @@ import (
 	"fmt"
 	"io"
 	"strings"
+
+	"git.portale-stac.it/go-pkg/expr/kern"
 )
 
 const (
@@ -15,7 +17,7 @@ const (
 )
 
 // --- Start of function definitions
-func doJoinStr(funcName string, sep string, it Iterator) (result any, err error) {
+func doJoinStr(funcName string, sep string, it kern.Iterator) (result any, err error) {
 	var sb strings.Builder
 	var v any
 	for v, err = it.Next(); err == nil; v, err = it.Next() {
@@ -25,7 +27,7 @@ func doJoinStr(funcName string, sep string, it Iterator) (result any, err error)
 		if s, ok := v.(string); ok {
 			sb.WriteString(s)
 		} else {
-			err = ErrExpectedGot(funcName, TypeString, v)
+			err = kern.ErrExpectedGot(funcName, kern.TypeString, v)
 			return
 		}
 	}
@@ -36,45 +38,45 @@ func doJoinStr(funcName string, sep string, it Iterator) (result any, err error)
 	return
 }
 
-func joinStrFunc(ctx ExprContext, name string, args map[string]any) (result any, err error) {
-	if sep, ok := args[ParamSeparator].(string); ok {
-		if v, exists := args[ParamItem]; exists {
+func joinStrFunc(ctx kern.ExprContext, name string, args map[string]any) (result any, err error) {
+	if sep, ok := args[kern.ParamSeparator].(string); ok {
+		if v, exists := args[kern.ParamItem]; exists {
 			argv := v.([]any)
 			if len(argv) == 1 {
-				if ls, ok := argv[0].(*ListType); ok {
+				if ls, ok := argv[0].(*kern.ListType); ok {
 					result, err = doJoinStr(name, sep, NewListIterator(ls, nil))
-				} else if it, ok := argv[0].(Iterator); ok {
+				} else if it, ok := argv[0].(kern.Iterator); ok {
 					result, err = doJoinStr(name, sep, it)
 				} else if s, ok := argv[0].(string); ok {
 					result = s
 				} else {
-					err = ErrInvalidParameterValue(name, ParamItem, v)
+					err = kern.ErrInvalidParameterValue(name, kern.ParamItem, v)
 				}
 			} else {
 				result, err = doJoinStr(name, sep, NewArrayIterator(argv))
 			}
 		}
 	} else {
-		err = ErrWrongParamType(name, ParamSeparator, TypeString, args[ParamSeparator])
+		err = kern.ErrWrongParamType(name, kern.ParamSeparator, kern.TypeString, args[kern.ParamSeparator])
 	}
 	return
 }
 
-func subStrFunc(ctx ExprContext, name string, args map[string]any) (result any, err error) {
+func subStrFunc(ctx kern.ExprContext, name string, args map[string]any) (result any, err error) {
 	var start = 0
 	var count = -1
 	var source string
 	var ok bool
 
-	if source, ok = args[ParamSource].(string); !ok {
-		return nil, ErrWrongParamType(name, ParamSource, TypeString, args[ParamSource])
+	if source, ok = args[kern.ParamSource].(string); !ok {
+		return nil, kern.ErrWrongParamType(name, kern.ParamSource, kern.TypeString, args[kern.ParamSource])
 	}
 
-	if start, err = ToGoInt(args[ParamStart], name+"()"); err != nil {
+	if start, err = kern.ToGoInt(args[kern.ParamStart], name+"()"); err != nil {
 		return
 	}
 
-	if count, err = ToGoInt(args[ParamCount], name+"()"); err != nil {
+	if count, err = kern.ToGoInt(args[kern.ParamCount], name+"()"); err != nil {
 		return
 	}
 
@@ -90,29 +92,29 @@ func subStrFunc(ctx ExprContext, name string, args map[string]any) (result any,
 	return
 }
 
-func trimStrFunc(ctx ExprContext, name string, args map[string]any) (result any, err error) {
+func trimStrFunc(ctx kern.ExprContext, name string, args map[string]any) (result any, err error) {
 	var source string
 	var ok bool
 
-	if source, ok = args[ParamSource].(string); !ok {
-		return nil, ErrWrongParamType(name, ParamSource, TypeString, args[ParamSource])
+	if source, ok = args[kern.ParamSource].(string); !ok {
+		return nil, kern.ErrWrongParamType(name, kern.ParamSource, kern.TypeString, args[kern.ParamSource])
 	}
 	result = strings.TrimSpace(source)
 	return
 }
 
-func startsWithStrFunc(ctx ExprContext, name string, args map[string]any) (result any, err error) {
+func startsWithStrFunc(ctx kern.ExprContext, name string, args map[string]any) (result any, err error) {
 	var source, prefix string
 	var ok bool
 
 	result = false
 
-	if source, ok = args[ParamSource].(string); !ok {
-		return result, ErrWrongParamType(name, ParamSource, TypeString, args[ParamSource])
+	if source, ok = args[kern.ParamSource].(string); !ok {
+		return result, kern.ErrWrongParamType(name, kern.ParamSource, kern.TypeString, args[kern.ParamSource])
 	}
 
-	if prefix, ok = args[ParamPrefix].(string); !ok {
-		return result, ErrWrongParamType(name, ParamPrefix, TypeString, args[ParamPrefix])
+	if prefix, ok = args[kern.ParamPrefix].(string); !ok {
+		return result, kern.ErrWrongParamType(name, kern.ParamPrefix, kern.TypeString, args[kern.ParamPrefix])
 	}
 	if strings.HasPrefix(source, prefix) {
 		result = true
@@ -125,7 +127,7 @@ func startsWithStrFunc(ctx ExprContext, name string, args map[string]any) (resul
 					break
 				}
 			} else {
-				err = fmt.Errorf("target item nr %d is %s, string expected", i+1, TypeName(targetSpec))
+				err = fmt.Errorf("target item nr %d is %s, string expected", i+1, kern.TypeName(targetSpec))
 				break
 			}
 		}
@@ -133,18 +135,18 @@ func startsWithStrFunc(ctx ExprContext, name string, args map[string]any) (resul
 	return
 }
 
-func endsWithStrFunc(ctx ExprContext, name string, args map[string]any) (result any, err error) {
+func endsWithStrFunc(ctx kern.ExprContext, name string, args map[string]any) (result any, err error) {
 	var source, suffix string
 	var ok bool
 
 	result = false
 
-	if source, ok = args[ParamSource].(string); !ok {
-		return result, ErrWrongParamType(name, ParamSource, TypeString, args[ParamSource])
+	if source, ok = args[kern.ParamSource].(string); !ok {
+		return result, kern.ErrWrongParamType(name, kern.ParamSource, kern.TypeString, args[kern.ParamSource])
 	}
 
-	if suffix, ok = args[ParamSuffix].(string); !ok {
-		return result, ErrWrongParamType(name, ParamSuffix, TypeString, args[ParamSuffix])
+	if suffix, ok = args[kern.ParamSuffix].(string); !ok {
+		return result, kern.ErrWrongParamType(name, kern.ParamSuffix, kern.TypeString, args[kern.ParamSuffix])
 	}
 	if strings.HasPrefix(source, suffix) {
 		result = true
@@ -157,7 +159,7 @@ func endsWithStrFunc(ctx ExprContext, name string, args map[string]any) (result
 					break
 				}
 			} else {
-				err = fmt.Errorf("target item nr %d is %s, string expected", i+1, TypeName(targetSpec))
+				err = fmt.Errorf("target item nr %d is %s, string expected", i+1, kern.TypeName(targetSpec))
 				break
 			}
 		}
@@ -165,24 +167,24 @@ func endsWithStrFunc(ctx ExprContext, name string, args map[string]any) (result
 	return
 }
 
-func splitStrFunc(ctx ExprContext, name string, args map[string]any) (result any, err error) {
+func splitStrFunc(ctx kern.ExprContext, name string, args map[string]any) (result any, err error) {
 	var source, sep string
 	var count int = -1
 	var parts []string
 	var ok bool
 
-	if source, ok = args[ParamSource].(string); !ok {
-		return result, ErrWrongParamType(name, ParamSource, TypeString, args[ParamSource])
+	if source, ok = args[kern.ParamSource].(string); !ok {
+		return result, kern.ErrWrongParamType(name, kern.ParamSource, kern.TypeString, args[kern.ParamSource])
 	}
 
-	if sep, ok = args[ParamSeparator].(string); !ok {
-		return nil, fmt.Errorf("separator param must be string, got %s (%v)", TypeName(args[ParamSeparator]), args[ParamSeparator])
+	if sep, ok = args[kern.ParamSeparator].(string); !ok {
+		return nil, fmt.Errorf("separator param must be string, got %s (%v)", kern.TypeName(args[kern.ParamSeparator]), args[kern.ParamSeparator])
 	}
 
-	if count64, ok := args[ParamCount].(int64); ok { // TODO replace type assertion with toInt()
+	if count64, ok := args[kern.ParamCount].(int64); ok { // TODO replace type assertion with toInt()
 		count = int(count64)
 	} else {
-		return nil, fmt.Errorf("part count must be integer, got %s (%v)", TypeName(args[ParamCount]), args[ParamCount])
+		return nil, fmt.Errorf("part count must be integer, got %s (%v)", kern.TypeName(args[kern.ParamCount]), args[kern.ParamCount])
 	}
 
 	if count > 0 {
@@ -192,7 +194,7 @@ func splitStrFunc(ctx ExprContext, name string, args map[string]any) (result any
 	} else {
 		parts = []string{}
 	}
-	list := make(ListType, len(parts))
+	list := make(kern.ListType, len(parts))
 	for i, part := range parts {
 		list[i] = part
 	}
@@ -200,20 +202,20 @@ func splitStrFunc(ctx ExprContext, name string, args map[string]any) (result any
 	return
 }
 
-func upperStrFunc(ctx ExprContext, name string, args map[string]any) (result any, err error) {
-	if source, ok := args[ParamSource].(string); ok {
+func upperStrFunc(ctx kern.ExprContext, name string, args map[string]any) (result any, err error) {
+	if source, ok := args[kern.ParamSource].(string); ok {
 		result = strings.ToUpper(source)
 	} else {
-		err = ErrWrongParamType(name, ParamSource, TypeString, args[ParamSource])
+		err = kern.ErrWrongParamType(name, kern.ParamSource, kern.TypeString, args[kern.ParamSource])
 	}
 	return
 }
 
-func lowerStrFunc(ctx ExprContext, name string, args map[string]any) (result any, err error) {
-	if source, ok := args[ParamSource].(string); ok {
+func lowerStrFunc(ctx kern.ExprContext, name string, args map[string]any) (result any, err error) {
+	if source, ok := args[kern.ParamSource].(string); ok {
 		result = strings.ToLower(source)
 	} else {
-		err = ErrWrongParamType(name, ParamSource, TypeString, args[ParamSource])
+		err = kern.ErrWrongParamType(name, kern.ParamSource, kern.TypeString, args[kern.ParamSource])
 	}
 	return
 }
@@ -221,46 +223,46 @@ func lowerStrFunc(ctx ExprContext, name string, args map[string]any) (result any
 // --- End of function definitions
 
 // Import above functions in the context
-func ImportStringFuncs(ctx ExprContext) {
-	ctx.RegisterFunc("strJoin", NewGolangFunctor(joinStrFunc), TypeString, []ExprFuncParam{
-		NewFuncParam(ParamSeparator),
-		NewFuncParamFlag(ParamItem, PfRepeat),
+func ImportStringFuncs(ctx kern.ExprContext) {
+	ctx.RegisterFunc("strJoin", kern.NewGolangFunctor(joinStrFunc), kern.TypeString, []kern.ExprFuncParam{
+		NewFuncParam(kern.ParamSeparator),
+		NewFuncParamFlag(kern.ParamItem, PfRepeat),
 	})
 
-	ctx.RegisterFunc("strSub", NewGolangFunctor(subStrFunc), TypeString, []ExprFuncParam{
-		NewFuncParam(ParamSource),
-		NewFuncParamFlagDef(ParamStart, PfDefault, int64(0)),
-		NewFuncParamFlagDef(ParamCount, PfDefault, int64(-1)),
+	ctx.RegisterFunc("strSub", kern.NewGolangFunctor(subStrFunc), kern.TypeString, []kern.ExprFuncParam{
+		NewFuncParam(kern.ParamSource),
+		NewFuncParamFlagDef(kern.ParamStart, PfDefault, int64(0)),
+		NewFuncParamFlagDef(kern.ParamCount, PfDefault, int64(-1)),
 	})
 
-	ctx.RegisterFunc("strSplit", NewGolangFunctor(splitStrFunc), "list of "+TypeString, []ExprFuncParam{
-		NewFuncParam(ParamSource),
-		NewFuncParamFlagDef(ParamSeparator, PfDefault, ""),
-		NewFuncParamFlagDef(ParamCount, PfDefault, int64(-1)),
+	ctx.RegisterFunc("strSplit", kern.NewGolangFunctor(splitStrFunc), "list of "+kern.TypeString, []kern.ExprFuncParam{
+		NewFuncParam(kern.ParamSource),
+		NewFuncParamFlagDef(kern.ParamSeparator, PfDefault, ""),
+		NewFuncParamFlagDef(kern.ParamCount, PfDefault, int64(-1)),
 	})
 
-	ctx.RegisterFunc("strTrim", NewGolangFunctor(trimStrFunc), TypeString, []ExprFuncParam{
-		NewFuncParam(ParamSource),
+	ctx.RegisterFunc("strTrim", kern.NewGolangFunctor(trimStrFunc), kern.TypeString, []kern.ExprFuncParam{
+		NewFuncParam(kern.ParamSource),
 	})
 
-	ctx.RegisterFunc("strStartsWith", NewGolangFunctor(startsWithStrFunc), TypeBoolean, []ExprFuncParam{
-		NewFuncParam(ParamSource),
-		NewFuncParam(ParamPrefix),
+	ctx.RegisterFunc("strStartsWith", kern.NewGolangFunctor(startsWithStrFunc), kern.TypeBoolean, []kern.ExprFuncParam{
+		NewFuncParam(kern.ParamSource),
+		NewFuncParam(kern.ParamPrefix),
 		NewFuncParamFlag(strParamOther, PfRepeat),
 	})
 
-	ctx.RegisterFunc("strEndsWith", NewGolangFunctor(endsWithStrFunc), TypeBoolean, []ExprFuncParam{
-		NewFuncParam(ParamSource),
-		NewFuncParam(ParamSuffix),
+	ctx.RegisterFunc("strEndsWith", kern.NewGolangFunctor(endsWithStrFunc), kern.TypeBoolean, []kern.ExprFuncParam{
+		NewFuncParam(kern.ParamSource),
+		NewFuncParam(kern.ParamSuffix),
 		NewFuncParamFlag(strParamOther, PfRepeat),
 	})
 
-	ctx.RegisterFunc("strUpper", NewGolangFunctor(upperStrFunc), TypeString, []ExprFuncParam{
-		NewFuncParam(ParamSource),
+	ctx.RegisterFunc("strUpper", kern.NewGolangFunctor(upperStrFunc), kern.TypeString, []kern.ExprFuncParam{
+		NewFuncParam(kern.ParamSource),
 	})
 
-	ctx.RegisterFunc("strLower", NewGolangFunctor(lowerStrFunc), TypeString, []ExprFuncParam{
-		NewFuncParam(ParamSource),
+	ctx.RegisterFunc("strLower", kern.NewGolangFunctor(lowerStrFunc), kern.TypeString, []kern.ExprFuncParam{
+		NewFuncParam(kern.ParamSource),
 	})
 }
 

builtins-register.go

@@ -6,21 +6,23 @@ package expr
 
 import (
 	"fmt"
+
+	"git.portale-stac.it/go-pkg/expr/kern"
 )
 
 type builtinModule struct {
-	importFunc  func(ExprContext)
+	importFunc  func(kern.ExprContext)
 	description string
 	imported    bool
 }
 
-func newBuiltinModule(importFunc func(ExprContext), description string) *builtinModule {
+func newBuiltinModule(importFunc func(kern.ExprContext), description string) *builtinModule {
 	return &builtinModule{importFunc, description, false}
 }
 
 var builtinModuleRegister map[string]*builtinModule
 
-func RegisterBuiltinModule(name string, importFunc func(ExprContext), description string) {
+func RegisterBuiltinModule(name string, importFunc func(kern.ExprContext), description string) {
 	if builtinModuleRegister == nil {
 		builtinModuleRegister = make(map[string]*builtinModule)
 	}

data-cursor.go

@@ -7,24 +7,26 @@ package expr
 import (
 	"io"
 	"slices"
+
+	"git.portale-stac.it/go-pkg/expr/kern"
 )
 
 type dataCursor struct {
-	ds        map[string]Functor
-	ctx       ExprContext
+	ds        map[string]kern.Functor
+	ctx       kern.ExprContext
 	initState bool // true if no item has produced yet (this replace di initial Next() call in the contructor)
 	// cursorValid bool // true if resource is nil or if clean has not yet been called
-	index     int
-	count     int
+	index     int64
+	count     int64
 	current   any
 	lastErr   error
 	resource  any
-	nextFunc  Functor
-	cleanFunc Functor
-	resetFunc Functor
+	nextFunc  kern.Functor
+	cleanFunc kern.Functor
+	resetFunc kern.Functor
 }
 
-func NewDataCursor(ctx ExprContext, ds map[string]Functor, resource any) (dc *dataCursor) {
+func NewDataCursor(ctx kern.ExprContext, ds map[string]kern.Functor, resource any) (dc *dataCursor) {
 	dc = &dataCursor{
 		ds:        ds,
 		initState: true,
@@ -35,14 +37,14 @@ func NewDataCursor(ctx ExprContext, ds map[string]Functor, resource any) (dc *da
 		lastErr:   nil,
 		resource:  resource,
 		ctx:       ctx.Clone(),
-		nextFunc:  ds[NextName],
-		cleanFunc: ds[CleanName],
-		resetFunc: ds[ResetName],
+		nextFunc:  ds[kern.NextName],
+		cleanFunc: ds[kern.CleanName],
+		resetFunc: ds[kern.ResetName],
 	}
 	return
 }
 
-func (dc *dataCursor) Context() ExprContext {
+func (dc *dataCursor) Context() kern.ExprContext {
 	return dc.ctx
 }
 
@@ -79,27 +81,27 @@ func (dc *dataCursor) String() string {
 }
 
 func (dc *dataCursor) HasOperation(name string) (exists bool) {
-	exists = slices.Contains([]string{CleanName, ResetName, CurrentName, IndexName}, name)
+	exists = slices.Contains([]string{kern.CleanName, kern.ResetName, kern.CurrentName, kern.IndexName}, name)
 	if !exists {
 		f, ok := dc.ds[name]
-		exists = ok && isFunctor(f)
+		exists = ok && kern.IsFunctor(f)
 	}
 	return
 }
 
 func (dc *dataCursor) CallOperation(name string, args map[string]any) (value any, err error) {
-	if name == IndexName {
+	if name == kern.IndexName {
 		value = int64(dc.Index())
-	} else if name == CleanName {
+	} else if name == kern.CleanName {
 		err = dc.Clean()
-	} else if name == ResetName {
+	} else if name == kern.ResetName {
 		err = dc.Reset()
-	} else if functor, ok := dc.ds[name]; ok && isFunctor(functor) {
-		ctx := cloneContext(dc.ctx)
+	} else if functor, ok := dc.ds[name]; ok && kern.IsFunctor(functor) {
+		ctx := kern.CloneContext(dc.ctx)
 		value, err = functor.InvokeNamed(ctx, name, args)
-		exportObjects(dc.ctx, ctx)
+		kern.ExportObjects(dc.ctx, ctx)
 	} else {
-		err = errNoOperation(name)
+		err = kern.ErrNoOperation(name)
 	}
 	return
 }
@@ -127,10 +129,10 @@ func (dc *dataCursor) CallOperation(name string, args map[string]any) (value any
 
 func (dc *dataCursor) Reset() (err error) {
 	if dc.resetFunc != nil {
-		ctx := cloneContext(dc.ctx)
-		actualParams := bindActualParams(dc.resetFunc, []any{dc.resource})
-		_, err = dc.resetFunc.InvokeNamed(ctx, ResetName, actualParams)
-		exportObjects(dc.ctx, ctx)
+		ctx := kern.CloneContext(dc.ctx)
+		actualParams := kern.BindActualParams(dc.resetFunc, []any{dc.resource})
+		_, err = dc.resetFunc.InvokeNamed(ctx, kern.ResetName, actualParams)
+		kern.ExportObjects(dc.ctx, ctx)
 	}
 	dc.index = -1
 	dc.count = 0
@@ -142,10 +144,10 @@ func (dc *dataCursor) Reset() (err error) {
 
 func (dc *dataCursor) Clean() (err error) {
 	if dc.cleanFunc != nil {
-		ctx := cloneContext(dc.ctx)
-		actualParams := bindActualParams(dc.cleanFunc, []any{dc.resource})
-		_, err = dc.cleanFunc.InvokeNamed(ctx, CleanName, actualParams)
-		exportObjects(dc.ctx, ctx)
+		ctx := kern.CloneContext(dc.ctx)
+		actualParams := kern.BindActualParams(dc.cleanFunc, []any{dc.resource})
+		_, err = dc.cleanFunc.InvokeNamed(ctx, kern.CleanName, actualParams)
+		kern.ExportObjects(dc.ctx, ctx)
 	}
 	dc.lastErr = io.EOF
 	return
@@ -178,13 +180,13 @@ func (dc *dataCursor) Current() (item any, err error) { // must return io.EOF at
 	return
 }
 
-func (dc *dataCursor) checkFilter(filter Functor, item any) (accepted bool, err error) {
+func (dc *dataCursor) checkFilter(filter kern.Functor, item any) (accepted bool, err error) {
 	var v any
 	var ok bool
-	ctx := cloneContext(dc.ctx)
+	ctx := kern.CloneContext(dc.ctx)
 
-	actualParams := bindActualParams(filter, []any{item, dc.index})
-	if v, err = filter.InvokeNamed(ctx, FilterName, actualParams); err == nil && v != nil {
+	actualParams := kern.BindActualParams(filter, []any{item, dc.index})
+	if v, err = filter.InvokeNamed(ctx, kern.FilterName, actualParams); err == nil && v != nil {
 		if accepted, ok = v.(bool); !ok {
 			accepted = true // NOTE: A non-boolean value that is not nil means the item has been accepted
 		}
@@ -192,10 +194,10 @@ func (dc *dataCursor) checkFilter(filter Functor, item any) (accepted bool, err
 	return
 }
 
-func (dc *dataCursor) mapItem(mapper Functor, item any) (mappedItem any, err error) {
-	ctx := cloneContext(dc.ctx)
-	actualParams := bindActualParams(mapper, []any{item, dc.index})
-	mappedItem, err = mapper.InvokeNamed(ctx, MapName, actualParams)
+func (dc *dataCursor) mapItem(mapper kern.Functor, item any) (mappedItem any, err error) {
+	ctx := kern.CloneContext(dc.ctx)
+	actualParams := kern.BindActualParams(mapper, []any{item, dc.index})
+	mappedItem, err = mapper.InvokeNamed(ctx, kern.MapName, actualParams)
 	return
 }
 
@@ -213,15 +215,15 @@ func (dc *dataCursor) Next() (current any, err error) { // must return io.EOF af
 		return
 	}
 	current = dc.current
-	filter := dc.ds[FilterName]
-	mapper := dc.ds[MapName]
+	filter := dc.ds[kern.FilterName]
+	mapper := dc.ds[kern.MapName]
 	var item any
 	for item == nil && dc.lastErr == nil {
-		ctx := cloneContext(dc.ctx)
+		ctx := kern.CloneContext(dc.ctx)
 		dc.index++
 
-		actualParams := bindActualParams(dc.nextFunc, []any{dc.resource, dc.index})
-		if item, dc.lastErr = dc.nextFunc.InvokeNamed(ctx, NextName, actualParams); dc.lastErr == nil {
+		actualParams := kern.BindActualParams(dc.nextFunc, []any{dc.resource, dc.index})
+		if item, dc.lastErr = dc.nextFunc.InvokeNamed(ctx, kern.NextName, actualParams); dc.lastErr == nil {
 			if item == nil {
 				dc.lastErr = io.EOF
 			} else {
@@ -239,7 +241,7 @@ func (dc *dataCursor) Next() (current any, err error) { // must return io.EOF af
 				}
 			}
 		}
-		exportObjects(dc.ctx, ctx)
+		kern.ExportObjects(dc.ctx, ctx)
 	}
 	dc.current = item
 	if dc.lastErr != nil {
@@ -296,10 +298,10 @@ func (dc *dataCursor) Next() (current any, err error) { // must return io.EOF af
 // 	return
 // }
 
-func (dc *dataCursor) Index() int {
+func (dc *dataCursor) Index() int64 {
 	return dc.index - 1
 }
 
-func (dc *dataCursor) Count() int {
+func (dc *dataCursor) Count() int64 {
 	return dc.count
 }

dict-iterator.go

@@ -9,6 +9,8 @@ import (
 	"io"
 	"slices"
 	"strings"
+
+	"git.portale-stac.it/go-pkg/expr/kern"
 )
 
 type dictIterMode int
@@ -20,9 +22,9 @@ const (
 )
 
 type DictIterator struct {
-	a        *DictType
-	count    int
-	index    int
+	a        *kern.DictType
+	count    int64
+	index    int64
 	keys     []any
 	iterMode dictIterMode
 }
@@ -65,7 +67,7 @@ func (it *DictIterator) makeKeys(m map[any]any, sort sortType) {
 	}
 }
 
-func NewDictIterator(dict *DictType, args []any) (it *DictIterator, err error) {
+func NewDictIterator(dict *kern.DictType, args []any) (it *DictIterator, err error) {
 	var sortType = sortTypeNone
 	var s string
 	var argAny any
@@ -76,7 +78,7 @@ func NewDictIterator(dict *DictType, args []any) (it *DictIterator, err error) {
 	} else {
 		argAny = "default"
 	}
-	if s, err = ToGoString(argAny, "sort type"); err == nil {
+	if s, err = kern.ToGoString(argAny, "sort type"); err == nil {
 		switch strings.ToLower(s) {
 		case "a", "asc":
 			sortType = sortTypeAsc
@@ -97,7 +99,7 @@ func NewDictIterator(dict *DictType, args []any) (it *DictIterator, err error) {
 				argAny = "default"
 			}
 
-			if s, err = ToGoString(argAny, "iteration mode"); err == nil {
+			if s, err = kern.ToGoString(argAny, "iteration mode"); err == nil {
 				switch strings.ToLower(s) {
 				case "k", "key", "keys":
 					dictIt.iterMode = dictIterModeKeys
@@ -119,15 +121,15 @@ func NewDictIterator(dict *DictType, args []any) (it *DictIterator, err error) {
 }
 
 func NewMapIterator(m map[any]any) (it *DictIterator) {
-	it = &DictIterator{a: (*DictType)(&m), count: 0, index: -1, keys: nil}
+	it = &DictIterator{a: (*kern.DictType)(&m), count: 0, index: -1, keys: nil}
 	it.makeKeys(m, sortTypeNone)
 	return
 }
 
 func (it *DictIterator) String() string {
-	var l = 0
+	var l = int64(0)
 	if it.a != nil {
-		l = len(*it.a)
+		l = int64(len(*it.a))
 	}
 	return fmt.Sprintf("$({#%d})", l)
 }
@@ -138,45 +140,45 @@ func (it *DictIterator) TypeName() string {
 
 func (it *DictIterator) HasOperation(name string) bool {
 	// yes := name == NextName || name == ResetName || name == IndexName || name == CountName || name == CurrentName
-	yes := slices.Contains([]string{NextName, ResetName, IndexName, CountName, CurrentName, CleanName, KeyName, ValueName}, name)
+	yes := slices.Contains([]string{kern.NextName, kern.ResetName, kern.IndexName, kern.CountName, kern.CurrentName, kern.CleanName, kern.KeyName, kern.ValueName}, name)
 	return yes
 }
 
 func (it *DictIterator) CallOperation(name string, args map[string]any) (v any, err error) {
 	switch name {
-	case NextName:
+	case kern.NextName:
 		v, err = it.Next()
-	case ResetName:
+	case kern.ResetName:
 		err = it.Reset()
-	case CleanName:
+	case kern.CleanName:
 		err = it.Clean()
-	case IndexName:
+	case kern.IndexName:
 		v = int64(it.Index())
-	case CurrentName:
+	case kern.CurrentName:
 		v, err = it.Current()
-	case CountName:
+	case kern.CountName:
 		v = it.count
-	case KeyName:
-		if it.index >= 0 && it.index < len(it.keys) {
+	case kern.KeyName:
+		if it.index >= 0 && it.index < int64(len(it.keys)) {
 			v = it.keys[it.index]
 		} else {
 			err = io.EOF
 		}
-	case ValueName:
-		if it.index >= 0 && it.index < len(it.keys) {
+	case kern.ValueName:
+		if it.index >= 0 && it.index < int64(len(it.keys)) {
 			a := *(it.a)
 			v = a[it.keys[it.index]]
 		} else {
 			err = io.EOF
 		}
 	default:
-		err = errNoOperation(name)
+		err = kern.ErrNoOperation(name)
 	}
 	return
 }
 
 func (it *DictIterator) Current() (item any, err error) {
-	if it.index >= 0 && it.index < len(it.keys) {
+	if it.index >= 0 && it.index < int64(len(it.keys)) {
 		switch it.iterMode {
 		case dictIterModeKeys:
 			item = it.keys[it.index]
@@ -186,7 +188,7 @@ func (it *DictIterator) Current() (item any, err error) {
 		case dictIterModeItems:
 			a := *(it.a)
 			pair := []any{it.keys[it.index], a[it.keys[it.index]]}
-			item = newList(pair)
+			item = kern.NewList(pair)
 		}
 	} else {
 		err = io.EOF
@@ -202,11 +204,11 @@ func (it *DictIterator) Next() (item any, err error) {
 	return
 }
 
-func (it *DictIterator) Index() int {
+func (it *DictIterator) Index() int64 {
 	return it.index
 }
 
-func (it *DictIterator) Count() int {
+func (it *DictIterator) Count() int64 {
 	return it.count
 }
 

doc/Expr.adoc

@@ -1421,12 +1421,38 @@ Same as <<_add,add()>> but returns the product of the values of the parameters.
 [green]`24`
 
 ==== Module "os.file"
+The "os.file" module provides functions for working with files.
+
+Activation: +
+`{4sp}builtin "os.file"`
+
+Currently available functions:
+
+* <<_fileOpen,fileOpen()>>
+* <<_fileAppend,fileAppend()>>
+* <<_fileCreate,fileCreate()>>
+* <<_fileClose,fileClose()>>
+* <<_fileWriteText,fileWriteText()>>
+* <<_fileReadText,fileReadText()>>
+* <<_fileReadTextAll,fileReadTextAll()>>
+
+More functions will be added in the future.
+
+---
 
 ===== fileOpen()
+Syntax: +
+`{4sp}fileOpen(<file-path>) -> file-handle`
+
+Returns a file handle for the specified file path. The file is opened in read-write mode. If the file does not exist, it is created.
 
 ===== fileAppend()
 
 ===== fileCreate()
+Syntax: +
+`{4sp}fileCreate(<file-path>) -> file-handle`
+
+Creates or truncates the named _<file-path>_. If the file already exists, it is truncated. If the file does not exist, it is created with mode 0o666 (before umask). The associated file descriptor has mode [O_RDWR]. The directory containing the file must already exist.
 
 ===== fileClose()
 
@@ -1438,6 +1464,24 @@ Same as <<_add,add()>> but returns the product of the values of the parameters.
 
 
 ==== Module "string"
+This module provides functions for working with strings.
+
+Activation: +
+`{4sp}builtin "string"`
+
+
+Currently available functions:
+
+* <<_strJoin,strJoin()>>
+* <<_strSub,strSub()>>
+* <<_strSplit,strSplit()>>
+* <<_strTrim,strTrim()>>
+* <<_strStartsWith,strStartsWith()>>
+* <<_strEndsWith,strEndsWith()>>
+* <<_strUpper,strUpper()>>
+* <<_strLower,strLower()>>
+
+---
 
 ===== strJoin()
 Syntax: +

expr.go

@@ -4,9 +4,13 @@
 // expr.go
 package expr
 
+import (
+	kern "git.portale-stac.it/go-pkg/expr/kern"
+)
+
 // ----Expression interface
 type Expr interface {
-	Typer
-	Eval(ctx ExprContext) (result any, err error)
+	kern.Typer
+	Eval(ctx kern.ExprContext) (result any, err error)
 	String() string
 }

function.go

@@ -6,19 +6,20 @@ package expr
 
 import (
 	"fmt"
-	"strconv"
 	"strings"
+
+	"git.portale-stac.it/go-pkg/expr/kern"
 )
 
 // ---- Function template
-type FuncTemplate func(ctx ExprContext, name string, args map[string]any) (result any, err error)
+// type FuncTemplate func(ctx expr.ExprContext, name string, args map[string]any) (result any, err error)
 
 // ---- Common functor definition
-type baseFunctor struct {
-	info ExprFunc
+type BaseFunctor struct {
+	info kern.ExprFunc
 }
 
-func (functor *baseFunctor) ToString(opt FmtOpt) (s string) {
+func (functor *BaseFunctor) ToString(opt kern.FmtOpt) (s string) {
 	if functor.info != nil {
 		s = functor.info.ToString(opt)
 	} else {
@@ -27,23 +28,23 @@ func (functor *baseFunctor) ToString(opt FmtOpt) (s string) {
 	return s
 }
 
-func (functor *baseFunctor) GetParams() (params []ExprFuncParam) {
+func (functor *BaseFunctor) GetParams() (params []kern.ExprFuncParam) {
 	if functor.info != nil {
 		return functor.info.Params()
 	} else {
-		return []ExprFuncParam{}
+		return []kern.ExprFuncParam{}
 	}
 }
 
-func (functor *baseFunctor) SetFunc(info ExprFunc) {
+func (functor *BaseFunctor) SetFunc(info kern.ExprFunc) {
 	functor.info = info
 }
 
-func (functor *baseFunctor) GetFunc() ExprFunc {
+func (functor *BaseFunctor) GetFunc() kern.ExprFunc {
 	return functor.info
 }
 
-func (functor *baseFunctor) GetDefinitionContext() ExprContext {
+func (functor *BaseFunctor) GetDefinitionContext() kern.ExprContext {
 	return nil
 }
 
@@ -62,11 +63,11 @@ type funcParamInfo struct {
 	defaultValue any
 }
 
-func NewFuncParam(name string) ExprFuncParam {
+func NewFuncParam(name string) kern.ExprFuncParam {
 	return &funcParamInfo{name: name}
 }
 
-func NewFuncParamFlag(name string, flags paramFlags) ExprFuncParam {
+func NewFuncParamFlag(name string, flags paramFlags) kern.ExprFuncParam {
 	return &funcParamInfo{name: name, flags: flags}
 }
 
@@ -79,7 +80,7 @@ func (param *funcParamInfo) Name() string {
 }
 
 func (param *funcParamInfo) Type() string {
-	return TypeAny
+	return kern.TypeAny
 }
 
 func (param *funcParamInfo) IsDefault() bool {
@@ -100,17 +101,17 @@ func (param *funcParamInfo) DefaultValue() any {
 
 // --- Functions
 
-// funcInfo implements ExprFunc
+// funcInfo implements expr.ExprFunc
 type funcInfo struct {
 	name         string
 	minArgs      int
 	maxArgs      int
-	functor      Functor
-	formalParams []ExprFuncParam
+	functor      kern.Functor
+	formalParams []kern.ExprFuncParam
 	returnType   string
 }
 
-func newFuncInfo(name string, functor Functor, returnType string, params []ExprFuncParam) (info *funcInfo, err error) {
+func newFuncInfo(name string, functor kern.Functor, returnType string, params []kern.ExprFuncParam) (info *funcInfo, err error) {
 	var minArgs = 0
 	var maxArgs = 0
 	for _, p := range params {
@@ -138,7 +139,7 @@ func newFuncInfo(name string, functor Functor, returnType string, params []ExprF
 	return info, nil
 }
 
-func (info *funcInfo) Params() []ExprFuncParam {
+func (info *funcInfo) Params() []kern.ExprFuncParam {
 	return info.formalParams
 }
 
@@ -146,7 +147,7 @@ func (info *funcInfo) ReturnType() string {
 	return info.returnType
 }
 
-func (info *funcInfo) ToString(opt FmtOpt) string {
+func (info *funcInfo) ToString(opt kern.FmtOpt) string {
 	var sb strings.Builder
 	if len(info.Name()) == 0 {
 		sb.WriteString("func")
@@ -180,7 +181,7 @@ func (info *funcInfo) ToString(opt FmtOpt) string {
 	if len(info.returnType) > 0 {
 		sb.WriteString(info.returnType)
 	} else {
-		sb.WriteString(TypeAny)
+		sb.WriteString(kern.TypeAny)
 	}
 	sb.WriteString("{}")
 	return sb.String()
@@ -198,11 +199,11 @@ func (info *funcInfo) MaxArgs() int {
 	return info.maxArgs
 }
 
-func (info *funcInfo) Functor() Functor {
+func (info *funcInfo) Functor() kern.Functor {
 	return info.functor
 }
 
-func (info *funcInfo) AllocContext(parentCtx ExprContext) (ctx ExprContext) {
+func (info *funcInfo) AllocContext(parentCtx kern.ExprContext) (ctx kern.ExprContext) {
 	if defCtx := info.functor.GetDefinitionContext(); defCtx != nil {
 		ctx = defCtx.Clone()
 		ctx.SetParent(defCtx)
@@ -213,7 +214,7 @@ func (info *funcInfo) AllocContext(parentCtx ExprContext) (ctx ExprContext) {
 	return
 }
 
-func (info *funcInfo) ParamSpec(paramName string) ExprFuncParam {
+func (info *funcInfo) ParamSpec(paramName string) kern.ExprFuncParam {
 	for _, spec := range info.formalParams {
 		if spec.Name() == paramName {
 			return spec
@@ -222,7 +223,7 @@ func (info *funcInfo) ParamSpec(paramName string) ExprFuncParam {
 	return nil
 }
 
-func initActualParams(ctx ExprContext, info ExprFunc, callTerm *term) (actualParams map[string]any, err error) {
+func initActualParams(ctx kern.ExprContext, info kern.ExprFunc, callTerm *term) (actualParams map[string]any, err error) {
 	var varArgs []any
 	var varName string
 
@@ -237,10 +238,10 @@ func initActualParams(ctx ExprContext, info ExprFunc, callTerm *term) (actualPar
 	for i, tree := range callTerm.children {
 		var paramValue any
 		paramCtx := ctx.Clone()
-		if paramValue, err = tree.compute(paramCtx); err != nil {
+		if paramValue, err = tree.Compute(paramCtx); err != nil {
 			break
 		}
-		if paramName, namedParam := getAssignVarName(tree); namedParam {
+		if paramName, namedParam := kern.GetAssignVarName(tree); namedParam {
 			if info.ParamSpec(paramName) == nil {
 				err = fmt.Errorf("%s(): unknown param %q", info.Name(), paramName)
 				break
@@ -260,7 +261,7 @@ func initActualParams(ctx ExprContext, info ExprFunc, callTerm *term) (actualPar
 					actualParams[spec.Name()] = paramValue
 				}
 			} else {
-				err = ErrTooManyParams(info.Name(), len(formalParams), len(callTerm.children))
+				err = kern.ErrTooManyParams(info.Name(), len(formalParams), len(callTerm.children))
 				break
 			}
 		} else {
@@ -279,7 +280,7 @@ func initActualParams(ctx ExprContext, info ExprFunc, callTerm *term) (actualPar
 func (info *funcInfo) PrepareCall(name string, actualParams map[string]any) (err error) {
 	passedCount := len(actualParams)
 	if info.MinArgs() > passedCount {
-		err = ErrTooFewParams(name, info.MinArgs(), info.MaxArgs(), passedCount)
+		err = kern.ErrTooFewParams(name, info.MinArgs(), info.MaxArgs(), passedCount)
 		return
 	}
 
@@ -301,86 +302,86 @@ func (info *funcInfo) PrepareCall(name string, actualParams map[string]any) (err
 	}
 
 	if info.MaxArgs() >= 0 && info.MaxArgs() < len(actualParams) {
-		err = ErrTooManyParams(name, info.MaxArgs(), len(actualParams))
+		err = kern.ErrTooManyParams(name, info.MaxArgs(), len(actualParams))
 	}
 	return
 }
 
 // ----- Call a function ---
 
-func getAssignVarName(t *term) (name string, ok bool) {
-	if ok = t.symbol() == SymEqual; ok {
-		name = t.children[0].source()
-	}
-	return
-}
+// func getAssignVarName(t *term) (name string, ok bool) {
+// 	if ok = t.symbol() == SymEqual; ok {
+// 		name = t.children[0].source()
+// 	}
+// 	return
+// }
 
-func CallFunctionByTerm(parentCtx ExprContext, name string, callTerm *term) (result any, err error) {
-	var actualParams map[string]any
-	if info, exists := GetFuncInfo(parentCtx, name); exists {
-		if actualParams, err = initActualParams(parentCtx, info, callTerm); err == nil {
-			ctx := info.AllocContext(parentCtx)
-			if err = info.PrepareCall(name, actualParams); err == nil {
-				functor := info.Functor()
-				result, err = functor.InvokeNamed(ctx, name, actualParams)
-				exportObjectsToParent(ctx)
-			}
-		}
-	} else {
-		err = fmt.Errorf("unknown function %s()", name)
-	}
-	return
-}
+// func CallFunctionByTerm(parentCtx expr.ExprContext, name string, callTerm *term) (result any, err error) {
+// 	var actualParams map[string]any
+// 	if info, exists := GetFuncInfo(parentCtx, name); exists {
+// 		if actualParams, err = initActualParams(parentCtx, info, callTerm); err == nil {
+// 			ctx := info.AllocContext(parentCtx)
+// 			if err = info.PrepareCall(name, actualParams); err == nil {
+// 				functor := info.Functor()
+// 				result, err = functor.InvokeNamed(ctx, name, actualParams)
+// 				exportObjectsToParent(ctx)
+// 			}
+// 		}
+// 	} else {
+// 		err = fmt.Errorf("unknown function %s()", name)
+// 	}
+// 	return
+// }
 
-func CallFunctionByArgs(parentCtx ExprContext, name string, args []any) (result any, err error) {
-	var actualParams map[string]any
-	if info, exists := GetFuncInfo(parentCtx, name); exists {
-		functor := info.Functor()
-		actualParams = bindActualParams(functor, args)
-		ctx := info.AllocContext(parentCtx)
-		if err = info.PrepareCall(name, actualParams); err == nil {
-			result, err = functor.InvokeNamed(ctx, name, actualParams)
-			exportObjectsToParent(ctx)
-		}
-	} else {
-		err = fmt.Errorf("unknown function %s()", name)
-	}
-	return
-}
+// func CallFunctionByArgs(parentCtx expr.ExprContext, name string, args []any) (result any, err error) {
+// 	var actualParams map[string]any
+// 	if info, exists := GetFuncInfo(parentCtx, name); exists {
+// 		functor := info.Functor()
+// 		actualParams = bindActualParams(functor, args)
+// 		ctx := info.AllocContext(parentCtx)
+// 		if err = info.PrepareCall(name, actualParams); err == nil {
+// 			result, err = functor.InvokeNamed(ctx, name, actualParams)
+// 			exportObjectsToParent(ctx)
+// 		}
+// 	} else {
+// 		err = fmt.Errorf("unknown function %s()", name)
+// 	}
+// 	return
+// }
 
-func CallFunctionByParams(parentCtx ExprContext, name string, actualParams map[string]any) (result any, err error) {
-	//var actualParams map[string]any
-	if info, exists := GetFuncInfo(parentCtx, name); exists {
-		functor := info.Functor()
-		ctx := info.AllocContext(parentCtx)
-		if err = info.PrepareCall(name, actualParams); err == nil {
-			result, err = functor.InvokeNamed(ctx, name, actualParams)
-			exportObjectsToParent(ctx)
-		}
-	} else {
-		err = fmt.Errorf("unknown function %s()", name)
-	}
-	return
-}
+// func CallFunctionByParams(parentCtx expr.ExprContext, name string, actualParams map[string]any) (result any, err error) {
+// 	//var actualParams map[string]any
+// 	if info, exists := GetFuncInfo(parentCtx, name); exists {
+// 		functor := info.Functor()
+// 		ctx := info.AllocContext(parentCtx)
+// 		if err = info.PrepareCall(name, actualParams); err == nil {
+// 			result, err = functor.InvokeNamed(ctx, name, actualParams)
+// 			exportObjectsToParent(ctx)
+// 		}
+// 	} else {
+// 		err = fmt.Errorf("unknown function %s()", name)
+// 	}
+// 	return
+// }
 
-func GetParam(args map[string]any, paramName string, paramNum int) (value any, exists bool) {
-	if value, exists = args[paramName]; !exists {
-		if paramNum > 0 && paramNum <= len(args) {
-			value, exists = args["arg"+strconv.Itoa(paramNum)]
-		}
-	}
-	return
-}
+// func GetParam(args map[string]any, paramName string, paramNum int) (value any, exists bool) {
+// 	if value, exists = args[paramName]; !exists {
+// 		if paramNum > 0 && paramNum <= len(args) {
+// 			value, exists = args["arg"+strconv.Itoa(paramNum)]
+// 		}
+// 	}
+// 	return
+// }
 
-func bindActualParams(functor Functor, args []any) (actualParams map[string]any) {
-	formalParams := functor.GetParams()
-	actualParams = make(map[string]any, len(args))
-	for i, arg := range args {
-		if i < len(formalParams) {
-			actualParams[formalParams[i].Name()] = arg
-		} else {
-			actualParams["arg"+strconv.Itoa(i+1)] = arg
-		}
-	}
-	return
-}
+// func bindActualParams(functor Functor, args []any) (actualParams map[string]any) {
+// 	formalParams := functor.GetParams()
+// 	actualParams = make(map[string]any, len(args))
+// 	for i, arg := range args {
+// 		if i < len(formalParams) {
+// 			actualParams[formalParams[i].Name()] = arg
+// 		} else {
+// 			actualParams["arg"+strconv.Itoa(i+1)] = arg
+// 		}
+// 	}
+// 	return
+// }

global-context.go

@@ -7,101 +7,68 @@ package expr
 import (
 	"path/filepath"
 	"strings"
+
+	"git.portale-stac.it/go-pkg/expr/kern"
 )
 
-var globalCtx *SimpleStore
+//var globalCtx *SimpleStore
 
-func ImportInContext(name string) (exists bool) {
-	var mod *builtinModule
-	if mod, exists = builtinModuleRegister[name]; exists {
-		mod.importFunc(globalCtx)
-		mod.imported = true
+func ImportInContext(ctx kern.ExprContext, name string) (exists bool) {
+	if globalCtx := ctx.GetGlobal(); globalCtx != nil {
+		var mod *builtinModule
+		if mod, exists = builtinModuleRegister[name]; exists {
+			mod.importFunc(globalCtx)
+			mod.imported = true
+		}
 	}
 	return
 }
 
-func ImportInContextByGlobPattern(pattern string) (count int, err error) {
-	var matched bool
-	for name, mod := range builtinModuleRegister {
-		if matched, err = filepath.Match(pattern, name); err == nil {
-			if matched {
-				count++
-				mod.importFunc(globalCtx)
-				mod.imported = true
+func ImportInContextByGlobPattern(ctx kern.ExprContext, pattern string) (count int, err error) {
+	if globalCtx := ctx.GetGlobal(); globalCtx != nil {
+		var matched bool
+		for name, mod := range builtinModuleRegister {
+			if matched, err = filepath.Match(pattern, name); err == nil {
+				if matched {
+					count++
+					mod.importFunc(globalCtx)
+					mod.imported = true
+				}
+			} else {
+				break
 			}
-		} else {
-			break
 		}
 	}
 	return
 }
 
-func GetVar(ctx ExprContext, name string) (value any, exists bool) {
-	if value, exists = ctx.GetVar(name); !exists {
-		value, exists = globalCtx.GetVar(name)
-	}
-	return
-}
-
-func GetLocalFuncInfo(ctx ExprContext, name string) (item ExprFunc, exists bool) {
-	var v any
-	if len(name) > 0 {
-		if v, exists = ctx.GetVar(name); exists && isFunctor(v) {
-			f, _ := v.(Functor)
-			item = f.GetFunc()
-		} else {
-			item, exists = ctx.GetFuncInfo(name)
+func GlobalCtrlSet(ctx kern.ExprContext, name string, newValue any) (currentValue any) {
+	if globalCtx := ctx.GetGlobal(); globalCtx != nil {
+		if !strings.HasPrefix(name, "_") {
+			name = "_" + name
 		}
+
+		currentValue, _ = globalCtx.GetVar(name)
+		globalCtx.SetVar(name, newValue)
 	}
-	return
-}
-
-func GetFuncInfo(ctx ExprContext, name string) (item ExprFunc, exists bool) {
-	// if len(name) > 0 {
-	// 	if item, exists = GetLocalFuncInfo(ctx, name); exists {
-	// 		ownerCtx = ctx
-	// 	} else if item, exists = globalCtx.GetFuncInfo(name); exists {
-	// 		ownerCtx = globalCtx
-	// 	}
-	// }
-	item, exists, _ = GetFuncInfoAndOwner(ctx, name)
-	return
-}
-
-func GetFuncInfoAndOwner(ctx ExprContext, name string) (item ExprFunc, exists bool, ownerCtx ExprContext) {
-	if len(name) > 0 {
-		if item, exists = GetLocalFuncInfo(ctx, name); exists {
-			ownerCtx = ctx
-		} else if item, exists = globalCtx.GetFuncInfo(name); exists {
-			ownerCtx = globalCtx
-		}
-	}
-	return
-}
-
-func GlobalCtrlSet(name string, newValue any) (currentValue any) {
-	if !strings.HasPrefix(name, "_") {
-		name = "_" + name
-	}
-	currentValue, _ = globalCtx.GetVar(name)
-
-	globalCtx.SetVar(name, newValue)
 	return currentValue
 }
 
-func GlobalCtrlGet(name string) (currentValue any) {
-	if !strings.HasPrefix(name, "_") {
-		name = "_" + name
+func GlobalCtrlGet(ctx kern.ExprContext, name string) (currentValue any) {
+	if globalCtx := ctx.GetGlobal(); globalCtx != nil {
+		if !strings.HasPrefix(name, "_") {
+			name = "_" + name
+		}
+		currentValue, _ = globalCtx.GetVar(name)
 	}
-	currentValue, _ = globalCtx.GetVar(name)
 	return currentValue
 }
 
-func CtrlEnable(ctx ExprContext, name string) (currentStatus bool) {
+func CtrlEnable(ctx kern.ExprContext, name string) (currentStatus bool) {
 	if !strings.HasPrefix(name, "_") {
 		name = "_" + name
 	}
-	if v, exists := ctx.GetVar(name); exists && IsBool(v) {
+	if v, exists := ctx.GetVar(name); exists && kern.IsBool(v) {
 		currentStatus, _ = v.(bool)
 	}
 
@@ -109,11 +76,11 @@ func CtrlEnable(ctx ExprContext, name string) (currentStatus bool) {
 	return currentStatus
 }
 
-func CtrlDisable(ctx ExprContext, name string) (currentStatus bool) {
+func CtrlDisable(ctx kern.ExprContext, name string) (currentStatus bool) {
 	if !strings.HasPrefix(name, "_") {
 		name = "_" + name
 	}
-	if v, exists := ctx.GetVar(name); exists && IsBool(v) {
+	if v, exists := ctx.GetVar(name); exists && kern.IsBool(v) {
 		currentStatus, _ = v.(bool)
 	}
 
@@ -121,36 +88,39 @@ func CtrlDisable(ctx ExprContext, name string) (currentStatus bool) {
 	return currentStatus
 }
 
-func CtrlIsEnabled(ctx ExprContext, name string) (status bool) {
-	var v any
-	var exists bool
+// func CtrlIsEnabled(ctx ExprContext, name string) (status bool) {
+// 	var v any
+// 	var exists bool
 
-	if !strings.HasPrefix(name, "_") {
-		name = "_" + name
-	}
+// 	if !strings.HasPrefix(name, "_") {
+// 		name = "_" + name
+// 	}
 
-	if v, exists = ctx.GetVar(name); !exists {
-		v, exists = globalCtx.GetVar(name)
-	}
+// 	if v, exists = ctx.GetVar(name); !exists {
+// 		v, exists = globalCtx.GetVar(name)
+// 	}
 
-	if exists {
-		if b, ok := v.(bool); ok {
-			status = b
+// 	if exists {
+// 		if b, ok := v.(bool); ok {
+// 			status = b
+// 		}
+// 	}
+// 	return
+// }
+
+func getControlString(ctx kern.ExprContext, name string) (s string, exists bool) {
+	if globalCtx := ctx.GetGlobal(); globalCtx != nil {
+		var v any
+		if v, exists = globalCtx.GetVar(name); exists {
+			s, exists = v.(string)
 		}
 	}
 	return
 }
 
-func getControlString(name string) (s string, exists bool) {
-	var v any
-	if v, exists = globalCtx.GetVar(name); exists {
-		s, exists = v.(string)
-	}
+func InitGlobal() (ctx kern.ExprContext) {
+	ctx = NewSimpleStoreWithoutGlobalContext()
+	kern.InitDefaultVars(ctx)
+	ImportBuiltinsFuncs(ctx)
 	return
 }
-
-func init() {
-	globalCtx = NewSimpleStore()
-	initDefaultVars(globalCtx)
-	ImportBuiltinsFuncs(globalCtx)
-}

graph.go

@@ -53,7 +53,7 @@ func (r *Reticle) computeCharWidth() {
 			if v := ref.node.value(); v != nil {
 				ref.label = fmt.Sprintf("%v", v)
 			} else {
-				ref.label = ref.node.source()
+				ref.label = ref.node.Source()
 			}
 			r.colsWidth[c] = max(r.colsWidth[c], len(ref.label)+2) // +2 to make room for brakets
 		}

helpers.go

@@ -9,9 +9,12 @@ import (
 	"io"
 	"os"
 	"strings"
+
+	"git.portale-stac.it/go-pkg/expr/kern"
+	"git.portale-stac.it/go-pkg/expr/util"
 )
 
-func EvalString(ctx ExprContext, source string) (result any, err error) {
+func EvalString(ctx kern.ExprContext, source string) (result any, err error) {
 	var tree *ast
 
 	r := strings.NewReader(source)
@@ -34,21 +37,21 @@ func EvalStringA(source string, args ...Arg) (result any, err error) {
 }
 
 func EvalStringV(source string, args []Arg) (result any, err error) {
-	ctx := NewSimpleStore()
+	ctx := NewSimpleStoreWithoutGlobalContext()
 	for _, arg := range args {
-		if isFunc(arg.Value) {
-			if f, ok := arg.Value.(FuncTemplate); ok {
-				functor := NewGolangFunctor(f)
+		if util.IsFunc(arg.Value) {
+			if f, ok := arg.Value.(kern.FuncTemplate); ok {
+				functor := kern.NewGolangFunctor(f)
 				// ctx.RegisterFunc(arg.Name, functor, 0, -1)
-				ctx.RegisterFunc(arg.Name, functor, TypeAny, []ExprFuncParam{
-					NewFuncParamFlagDef(ParamValue, PfDefault|PfRepeat, 0),
+				ctx.RegisterFunc(arg.Name, functor, kern.TypeAny, []kern.ExprFuncParam{
+					NewFuncParamFlagDef(kern.ParamValue, PfDefault|PfRepeat, 0),
 				})
 			} else {
 				err = fmt.Errorf("invalid function specification: %q", arg.Name)
 			}
-		} else if integer, ok := anyInteger(arg.Value); ok {
+		} else if integer, ok := kern.AnyInteger(arg.Value); ok {
 			ctx.SetVar(arg.Name, integer)
-		} else if float, ok := anyFloat(arg.Value); ok {
+		} else if float, ok := kern.AnyFloat(arg.Value); ok {
 			ctx.SetVar(arg.Name, float)
 		} else if _, ok := arg.Value.(string); ok {
 			ctx.SetVar(arg.Name, arg.Value)
@@ -65,7 +68,7 @@ func EvalStringV(source string, args []Arg) (result any, err error) {
 	return
 }
 
-func EvalStream(ctx ExprContext, r io.Reader) (result any, err error) {
+func EvalStream(ctx kern.ExprContext, r io.Reader) (result any, err error) {
 	var tree *ast
 	scanner := NewScanner(r, DefaultTranslations())
 	parser := NewParser()
@@ -76,7 +79,7 @@ func EvalStream(ctx ExprContext, r io.Reader) (result any, err error) {
 	return
 }
 
-func EvalFile(ctx ExprContext, filePath string) (result any, err error) {
+func EvalFile(ctx kern.ExprContext, filePath string) (result any, err error) {
 	var fh *os.File
 	if fh, err = os.Open(filePath); err != nil {
 		return nil, err

import-utils.go

@@ -11,6 +11,9 @@ import (
 	"path"
 	"path/filepath"
 	"strings"
+
+	"git.portale-stac.it/go-pkg/expr/kern"
+	"git.portale-stac.it/go-pkg/expr/util"
 )
 
 const (
@@ -19,8 +22,8 @@ const (
 )
 
 func checkStringParamExpected(funcName string, paramValue any, paramPos int) (err error) {
-	if !(IsString(paramValue) /*|| isList(paramValue)*/) {
-		err = fmt.Errorf("%s(): param nr %d has wrong type %s, string expected", funcName, paramPos+1, TypeName(paramValue))
+	if !(kern.IsString(paramValue) /*|| isList(paramValue)*/) {
+		err = fmt.Errorf("%s(): param nr %d has wrong type %s, string expected", funcName, paramPos+1, kern.TypeName(paramValue))
 	}
 	return
 }
@@ -45,8 +48,8 @@ func addEnvImportDirs(envVarName string, dirList []string) []string {
 	return dirList
 }
 
-func addSearchDirs(endingPath string, dirList []string) []string {
-	if dirSpec, exists := getControlString(ControlSearchPath); exists {
+func addSearchDirs(ctx kern.ExprContext, endingPath string, dirList []string) []string {
+	if dirSpec, exists := getControlString(ctx, kern.ControlSearchPath); exists {
 		dirs := strings.Split(dirSpec, ":")
 		if dirList == nil {
 			dirList = dirs
@@ -63,9 +66,9 @@ func addSearchDirs(endingPath string, dirList []string) []string {
 	return dirList
 }
 
-func buildSearchDirList(endingPath, envVarName string) (dirList []string) {
+func buildSearchDirList(ctx kern.ExprContext, endingPath, envVarName string) (dirList []string) {
 	dirList = addEnvImportDirs(envVarName, dirList)
-	dirList = addSearchDirs(endingPath, dirList)
+	dirList = addSearchDirs(ctx, endingPath, dirList)
 	return
 }
 
@@ -83,7 +86,7 @@ func searchAmongPath(filename string, dirList []string) (filePath string) {
 	}
 
 	for _, dir := range dirList {
-		if dir, err = ExpandPath(dir); err != nil {
+		if dir, err = util.ExpandPath(dir); err != nil {
 			continue
 		}
 		if fullPath := path.Join(dir, filename); isFile(fullPath) {
@@ -106,7 +109,7 @@ func isPathRelative(filePath string) bool {
 }
 
 func makeFilepath(filename string, dirList []string) (filePath string, err error) {
-	if filename, err = ExpandPath(filename); err != nil {
+	if filename, err = util.ExpandPath(filename); err != nil {
 		return
 	}
 

int-iterator.go

@@ -0,0 +1,137 @@
+// Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
+// All rights reserved.
+
+// int-iterator.go
+package expr
+
+import (
+	"fmt"
+	"io"
+	"slices"
+
+	"git.portale-stac.it/go-pkg/expr/kern"
+)
+
+type IntIterator struct {
+	count int64
+	index int64
+	start int64
+	stop  int64
+	step  int64
+}
+
+func NewIntIterator(args []any) (it *IntIterator, err error) {
+	var argc int = 0
+	if args != nil {
+		argc = len(args)
+	}
+	it = &IntIterator{count: 0, index: -1, start: 0, stop: 0, step: 1}
+	if argc >= 1 {
+		if it.stop, err = kern.ToGoInt64(args[0], "start index"); err != nil {
+			return
+		}
+		if argc >= 2 {
+			it.start = it.stop
+			if it.stop, err = kern.ToGoInt64(args[1], "stop index"); err != nil {
+				return
+			}
+			if argc >= 3 {
+				if it.step, err = kern.ToGoInt64(args[2], "step"); err != nil {
+					return
+				}
+			} else if it.start > it.stop {
+				it.step = -1
+			}
+		}
+	}
+	if it.step == 0 {
+		err = fmt.Errorf("step cannot be zero")
+		return
+	}
+	if it.start < it.stop && it.step < 0 {
+		err = fmt.Errorf("step cannot be negative when start < stop")
+		return
+	}
+	if it.start > it.stop && it.step > 0 {
+		err = fmt.Errorf("step cannot be positive when start > stop")
+		return
+	}
+	it.Reset()
+	return
+}
+
+func (it *IntIterator) String() string {
+	return fmt.Sprintf("$(%d..%d..%d)", it.start, it.stop, it.step)
+}
+
+func (it *IntIterator) TypeName() string {
+	return "IntIterator"
+}
+
+func (it *IntIterator) HasOperation(name string) bool {
+	yes := slices.Contains([]string{kern.NextName, kern.ResetName, kern.IndexName, kern.CountName, kern.CurrentName}, name)
+	return yes
+}
+
+func (it *IntIterator) CallOperation(name string, args map[string]any) (v any, err error) {
+	switch name {
+	case kern.NextName:
+		v, err = it.Next()
+	case kern.ResetName:
+		err = it.Reset()
+	case kern.CleanName:
+		err = it.Clean()
+	case kern.IndexName:
+		v = int64(it.Index())
+	case kern.CurrentName:
+		v, err = it.Current()
+	case kern.CountName:
+		v = it.count
+	default:
+		err = kern.ErrNoOperation(name)
+	}
+	return
+}
+
+func (it *IntIterator) Current() (item any, err error) {
+	if it.start <= it.stop {
+		if it.index >= it.start && it.index < it.stop {
+			item = it.index
+		} else {
+			err = io.EOF
+		}
+	} else {
+		if it.index > it.stop && it.index <= it.start {
+			item = it.index
+		} else {
+			err = io.EOF
+		}
+	}
+	return
+}
+
+func (it *IntIterator) Next() (item any, err error) {
+	it.index += it.step
+	if item, err = it.Current(); err != io.EOF {
+		it.count++
+	}
+	return
+}
+
+func (it *IntIterator) Index() int64 {
+	return it.index
+}
+
+func (it *IntIterator) Count() int64 {
+	return it.count
+}
+
+func (it *IntIterator) Reset() error {
+	it.index = it.start - it.step
+	it.count = 0
+	return nil
+}
+
+func (it *IntIterator) Clean() error {
+	return nil
+}

iter-factory.go

@@ -4,19 +4,23 @@
 // iter-factory.go
 package expr
 
-func NewIterator(value any) (it Iterator, err error) {
+import (
+	"git.portale-stac.it/go-pkg/expr/kern"
+)
+
+func NewIterator(value any) (it kern.Iterator, err error) {
 	if value == nil {
 		return NewArrayIterator([]any{}), nil
 	}
 
 	switch v := value.(type) {
-	case *ListType:
+	case *kern.ListType:
 		it = NewListIterator(v, nil)
-	case *DictType:
+	case *kern.DictType:
 		it, err = NewDictIterator(v, nil)
 	case []any:
 		it = NewArrayIterator(v)
-	case Iterator:
+	case kern.Iterator:
 		it = v
 	default:
 		it = NewArrayIterator([]any{value})

kern/bind-go-functions.go

@@ -2,11 +2,11 @@
 // All rights reserved.
 
 // bind-go-function.go
-package expr
+package kern
 
 // ---- Linking with Go functions
 type golangFunctor struct {
-	baseFunctor
+	BaseFunctor
 	f FuncTemplate
 }
 

kern/bool.go

@@ -0,0 +1,27 @@
+// Copyright (c) 2024-2026 Celestino Amoroso (celestino.amoroso@gmail.com).
+// All rights reserved.
+
+// string.go
+package kern
+
+func IsBool(v any) (ok bool) {
+	_, ok = v.(bool)
+	return ok
+}
+
+func ToBool(v any) (b bool, ok bool) {
+	ok = true
+	switch x := v.(type) {
+	case string:
+		b = len(x) > 0
+	case float64:
+		b = x != 0.0
+	case int64:
+		b = x != 0
+	case bool:
+		b = x
+	default:
+		ok = false
+	}
+	return
+}

kern/common-errors.go

@@ -2,7 +2,7 @@
 // All rights reserved.
 
 // common-errors.go
-package expr
+package kern
 
 import (
 	"fmt"
@@ -86,6 +86,6 @@ func ErrUnknownVar(funcName, varName string) error {
 
 // --- Operator errors
 
-func ErrLeftOperandMustBeVariable(leftTerm, opTerm *term) error {
-	return leftTerm.Errorf("left operand of %q must be a variable", opTerm.source())
+func ErrLeftOperandMustBeVariable(leftTerm, opTerm Term) error {
+	return leftTerm.Errorf("left operand of %q must be a variable", opTerm.Source())
 }

kern/common-params.go

@@ -2,7 +2,7 @@
 // All rights reserved.
 
 // common-params.go
-package expr
+package kern
 
 const (
 	ParamArgs      = "args"

kern/common-type-names.go

@@ -2,7 +2,7 @@
 // All rights reserved.
 
 // common-type-names.go
-package expr
+package kern
 
 const (
 	TypeAny           = "any"

kern/context-helpers.go

@@ -2,9 +2,9 @@
 // All rights reserved.
 
 // context-helpers.go
-package expr
+package kern
 
-func cloneContext(sourceCtx ExprContext) (clonedCtx ExprContext) {
+func CloneContext(sourceCtx ExprContext) (clonedCtx ExprContext) {
 	if sourceCtx != nil {
 		clonedCtx = sourceCtx.Clone()
 	}
@@ -25,8 +25,8 @@ func exportFunc(ctx ExprContext, name string, info ExprFunc) {
 	ctx.RegisterFunc(name, info.Functor(), info.ReturnType(), info.Params())
 }
 
-func exportObjects(destCtx, sourceCtx ExprContext) {
-	exportAll := CtrlIsEnabled(sourceCtx, control_export_all)
+func ExportObjects(destCtx, sourceCtx ExprContext) {
+	exportAll := CtrlIsEnabled(sourceCtx, ControlExportAll)
 	// fmt.Printf("Exporting from sourceCtx [%p] to destCtx [%p] -- exportAll=%t\n", sourceCtx, destCtx, exportAll)
 	// Export variables
 	for _, refName := range sourceCtx.EnumVars(func(name string) bool { return (exportAll || name[0] == '@') && !(name[0] == '_') }) {
@@ -44,6 +44,6 @@ func exportObjects(destCtx, sourceCtx ExprContext) {
 
 func exportObjectsToParent(sourceCtx ExprContext) {
 	if parentCtx := sourceCtx.GetParent(); parentCtx != nil {
-		exportObjects(parentCtx, sourceCtx)
+		ExportObjects(parentCtx, sourceCtx)
 	}
 }

kern/control.go

@@ -2,7 +2,9 @@
 // All rights reserved.
 
 // control.go
-package expr
+package kern
+
+import "strings"
 
 // Preset control variables
 const (
@@ -16,7 +18,7 @@ const (
 
 // Other control variables
 const (
-	control_export_all = "_export_all"
+	ControlExportAll = "_export_all"
 )
 
 // Initial values
@@ -24,13 +26,34 @@ const (
 	init_search_path = "~/.local/lib/go-pkg/expr:/usr/local/lib/go-pkg/expr:/usr/lib/go-pkg/expr"
 )
 
+func CtrlIsEnabled(ctx ExprContext, name string) (status bool) {
+	var v any
+	var exists bool
+
+	if !strings.HasPrefix(name, "_") {
+		name = "_" + name
+	}
+
+	if v, exists = ctx.GetVar(name); !exists {
+		if globalCtx := ctx.GetGlobal(); globalCtx != nil {
+			v, exists = globalCtx.GetVar(name)
+		}
+	}
+
+	if exists {
+		if b, ok := v.(bool); ok {
+			status = b
+		}
+	}
+	return
+}
 func SetCtrl(ctx ExprContext, name string, value any) (current any) {
 	current, _ = ctx.GetVar(name)
 	ctx.UnsafeSetVar(name, value)
 	return
 }
 
-func initDefaultVars(ctx ExprContext) {
+func InitDefaultVars(ctx ExprContext) {
 	if _, exists := ctx.GetVar(ControlPreset); exists {
 		return
 	}

kern/dict-type.go

@@ -2,7 +2,7 @@
 // All rights reserved.
 
 // dict-type.go
-package expr
+package kern
 
 import (
 	"fmt"
@@ -12,6 +12,11 @@ import (
 
 type DictType map[any]any
 
+func IsDict(v any) (ok bool) {
+	_, ok = v.(*DictType)
+	return ok
+}
+
 func MakeDict() (dict *DictType) {
 	d := make(DictType)
 	dict = &d
@@ -32,7 +37,7 @@ func NewDict(dictAny map[any]any) (dict *DictType) {
 	return
 }
 
-func newDict(dictAny map[any]*term) (dict *DictType) {
+func newDict(dictAny map[any]Term) (dict *DictType) {
 	// TODO Change with a call to NewDict()
 	var d DictType
 	if dictAny != nil {
@@ -110,7 +115,7 @@ func (dict *DictType) ToString(opt FmtOpt) string {
 			sb.WriteString(": ")
 			if formatter, ok := value.(Formatter); ok {
 				sb.WriteString(formatter.ToString(opt))
-			} else if t, ok := value.(*term); ok {
+			} else if t, ok := value.(Term); ok {
 				sb.WriteString(t.String())
 			} else {
 				sb.WriteString(fmt.Sprintf("%#v", value))
@@ -129,7 +134,7 @@ func (dict *DictType) TypeName() string {
 	return "dict"
 }
 
-func (dict *DictType) hasKey(target any) (ok bool) {
+func (dict *DictType) HasKey(target any) (ok bool) {
 	for key := range *dict {
 		if ok = reflect.DeepEqual(key, target); ok {
 			break
@@ -138,7 +143,17 @@ func (dict *DictType) hasKey(target any) (ok bool) {
 	return
 }
 
-func (dict *DictType) clone() (c *DictType) {
+func (dict *DictType) SetItem(key any, value any) (err error) {
+	(*dict)[key] = value
+	return
+}
+
+func (dict *DictType) GetItem(key any) (value any, err error) {
+	value = (*dict)[key]
+	return
+}
+
+func (dict *DictType) Clone() (c *DictType) {
 	c = newDict(nil)
 	for k, v := range *dict {
 		(*c)[k] = v
@@ -146,7 +161,7 @@ func (dict *DictType) clone() (c *DictType) {
 	return
 }
 
-func (dict *DictType) merge(second *DictType) {
+func (dict *DictType) Merge(second *DictType) {
 	if second != nil {
 		for k, v := range *second {
 			(*dict)[k] = v
@@ -154,11 +169,6 @@ func (dict *DictType) merge(second *DictType) {
 	}
 }
 
-func (dict *DictType) setItem(key any, value any) (err error) {
-	(*dict)[key] = value
-	return
-}
-
 ////////////////
 
 type DictFormat interface {

kern/expr-context.go

@@ -2,13 +2,14 @@
 // All rights reserved.
 
 // expr-context.go
-package expr
+package kern
 
 // ----Expression Context
 type ExprContext interface {
 	Clone() ExprContext
 	SetParent(ctx ExprContext)
 	GetParent() (ctx ExprContext)
+	GetGlobal() (ctx ExprContext)
 	GetVar(varName string) (value any, exists bool)
 	GetLast() any
 	SetVar(varName string, value any)
@@ -22,6 +23,7 @@ type ExprContext interface {
 	FuncCount() int
 	DeleteFunc(funcName string)
 
+	GetLocalFuncInfo(name string) (info ExprFunc, exists bool)
 	GetFuncInfo(name string) (item ExprFunc, exists bool)
 	Call(name string, args map[string]any) (result any, err error)
 	RegisterFuncInfo(info ExprFunc)

kern/expr-function.go

@@ -2,7 +2,7 @@
 // All rights reserved.
 
 // expr-function.go
-package expr
+package kern
 
 // ---- Functor interface
 type Functor interface {

kern/float.go

@@ -0,0 +1,23 @@
+// Copyright (c) 2024-2026 Celestino Amoroso (celestino.amoroso@gmail.com).
+// All rights reserved.
+
+// float.go
+package kern
+
+func IsFloat(v any) (ok bool) {
+	_, ok = v.(float64)
+	return ok
+}
+
+func AnyFloat(v any) (float float64, ok bool) {
+	ok = true
+	switch floatval := v.(type) {
+	case float32:
+		float = float64(floatval)
+	case float64:
+		float = floatval
+	default:
+		ok = false
+	}
+	return
+}

kern/formatter.go

@@ -2,7 +2,7 @@
 // All rights reserved.
 
 // formatter.go
-package expr
+package kern
 
 import "fmt"
 
@@ -46,7 +46,7 @@ type Formatter interface {
 	ToString(options FmtOpt) string
 }
 
-func getFormatted(v any, opt FmtOpt) (text string) {
+func GetFormatted(v any, opt FmtOpt) (text string) {
 	if v == nil {
 		text = "(nil)"
 	} else if s, ok := v.(string); ok {

kern/fraction-type.go

@@ -2,7 +2,7 @@
 // All rights reserved.
 
 // fraction-type.go
-package expr
+package kern
 
 //https://www.youmath.it/lezioni/algebra-elementare/lezioni-di-algebra-e-aritmetica-per-scuole-medie/553-dalle-frazioni-a-numeri-decimali.html
 
@@ -18,12 +18,12 @@ type FractionType struct {
 	num, den int64
 }
 
-func newFraction(num, den int64) *FractionType {
+func NewFraction(num, den int64) *FractionType {
 	num, den = simplifyIntegers(num, den)
 	return &FractionType{num, den}
 }
 
-func float64ToFraction(f float64) (fract *FractionType, err error) {
+func Float64ToFraction(f float64) (fract *FractionType, err error) {
 	var sign string
 	intPart, decPart := math.Modf(f)
 	if decPart < 0.0 {
@@ -33,11 +33,11 @@ func float64ToFraction(f float64) (fract *FractionType, err error) {
 	}
 	dec := fmt.Sprintf("%.12f", decPart)
 	s := fmt.Sprintf("%s%.f%s", sign, intPart, dec[1:])
-	return makeGeneratingFraction(s)
+	return MakeGeneratingFraction(s)
 }
 
 // Based on https://cs.opensource.google/go/go/+/refs/tags/go1.22.3:src/math/big/rat.go;l=39
-func makeGeneratingFraction(s string) (f *FractionType, err error) {
+func MakeGeneratingFraction(s string) (f *FractionType, err error) {
 	var num, den int64
 	var sign int64 = 1
 	var parts []string
@@ -59,7 +59,7 @@ func makeGeneratingFraction(s string) (f *FractionType, err error) {
 		return
 	}
 	if len(parts) == 1 {
-		f = newFraction(sign*num, 1)
+		f = NewFraction(sign*num, 1)
 	} else if len(parts) == 2 {
 		subParts := strings.SplitN(parts[1], "(", 2)
 		if len(subParts) == 1 {
@@ -76,7 +76,7 @@ func makeGeneratingFraction(s string) (f *FractionType, err error) {
 				num = num*10 + int64(c-'0')
 				den = den * 10
 			}
-			f = newFraction(sign*num, den)
+			f = NewFraction(sign*num, den)
 		} else if len(subParts) == 2 {
 			sub := num
 			mul := int64(1)
@@ -103,7 +103,7 @@ func makeGeneratingFraction(s string) (f *FractionType, err error) {
 				den *= mul
 			}
 			num -= sub
-			f = newFraction(sign*num, den)
+			f = NewFraction(sign*num, den)
 		}
 	}
 exit:
@@ -113,7 +113,15 @@ exit:
 	return
 }
 
-func (f *FractionType) toFloat() float64 {
+func (f *FractionType) N() int64 {
+	return f.num
+}
+
+func (f *FractionType) D() int64 {
+	return f.den
+}
+
+func (f *FractionType) ToFloat() float64 {
 	return float64(f.num) / float64(f.den)
 }
 
@@ -168,7 +176,7 @@ func (f *FractionType) TypeName() string {
 // -------- fraction utility functions
 
 // greatest common divider
-func gcd(a, b int64) (g int64) {
+func Gcd(a, b int64) (g int64) {
 	if a < 0 {
 		a = -a
 	}
@@ -189,21 +197,21 @@ func gcd(a, b int64) (g int64) {
 
 // lower common multiple
 func lcm(a, b int64) (l int64) {
-	g := gcd(a, b)
+	g := Gcd(a, b)
 	l = a * b / g
 	return
 }
 
 // Sum two fractions
-func sumFract(f1, f2 *FractionType) (sum *FractionType) {
+func SumFract(f1, f2 *FractionType) (sum *FractionType) {
 	m := lcm(f1.den, f2.den)
-	sum = newFraction(f1.num*(m/f1.den)+f2.num*(m/f2.den), m)
+	sum = NewFraction(f1.num*(m/f1.den)+f2.num*(m/f2.den), m)
 	return
 }
 
 // Multiply two fractions
-func mulFract(f1, f2 *FractionType) (prod *FractionType) {
-	prod = newFraction(f1.num*f2.num, f1.den*f2.den)
+func MulFract(f1, f2 *FractionType) (prod *FractionType) {
+	prod = NewFraction(f1.num*f2.num, f1.den*f2.den)
 	return
 }
 
@@ -230,12 +238,12 @@ func anyPairToFract(v1, v2 any) (f1, f2 *FractionType, err error) {
 	return
 }
 
-func sumAnyFract(af1, af2 any) (sum any, err error) {
+func SumAnyFract(af1, af2 any) (sum any, err error) {
 	var f1, f2 *FractionType
 	if f1, f2, err = anyPairToFract(af1, af2); err != nil {
 		return
 	}
-	f := sumFract(f1, f2)
+	f := SumFract(f1, f2)
 	if f.num == 0 {
 		sum = 0
 	} else {
@@ -250,7 +258,7 @@ func sumAnyFract(af1, af2 any) (sum any, err error) {
 //		 =0 if af1 == af2
 //		 >0 if af1 > af2
 //	 err if af1 or af2 is not convertible to fraction
-func cmpAnyFract(af1, af2 any) (result int, err error) {
+func CmpAnyFract(af1, af2 any) (result int, err error) {
 	var f1, f2 *FractionType
 	if f1, f2, err = anyPairToFract(af1, af2); err != nil {
 		return
@@ -266,7 +274,7 @@ func cmpAnyFract(af1, af2 any) (result int, err error) {
 //	>0 if af1 > af2
 func cmpFract(f1, f2 *FractionType) (result int) {
 	f2.num = -f2.num
-	f := sumFract(f1, f2)
+	f := SumFract(f1, f2)
 	if f.num < 0 {
 		result = -1
 	} else if f.num > 0 {
@@ -277,13 +285,13 @@ func cmpFract(f1, f2 *FractionType) (result int) {
 	return
 }
 
-func subAnyFract(af1, af2 any) (sum any, err error) {
+func SubAnyFract(af1, af2 any) (sum any, err error) {
 	var f1, f2 *FractionType
 	if f1, f2, err = anyPairToFract(af1, af2); err != nil {
 		return
 	}
 	f2.num = -f2.num
-	f := sumFract(f1, f2)
+	f := SumFract(f1, f2)
 	if f.num == 0 {
 		sum = 0
 	} else {
@@ -292,7 +300,7 @@ func subAnyFract(af1, af2 any) (sum any, err error) {
 	return
 }
 
-func mulAnyFract(af1, af2 any) (prod any, err error) {
+func MulAnyFract(af1, af2 any) (prod any, err error) {
 	var f1, f2 *FractionType
 	if f1, f2, err = anyPairToFract(af1, af2); err != nil {
 		return
@@ -306,7 +314,7 @@ func mulAnyFract(af1, af2 any) (prod any, err error) {
 	return
 }
 
-func divAnyFract(af1, af2 any) (quot any, err error) {
+func DivAnyFract(af1, af2 any) (quot any, err error) {
 	var f1, f2 *FractionType
 	if f1, f2, err = anyPairToFract(af1, af2); err != nil {
 		return
@@ -345,7 +353,7 @@ func simplifyIntegers(num, den int64) (a, b int64) {
 		den = -den
 		num = -num
 	}
-	g := gcd(num, den)
+	g := Gcd(num, den)
 	a = num / g
 	b = den / g
 	return
@@ -355,7 +363,19 @@ func intToFraction(n int64) *FractionType {
 	return &FractionType{n, 1}
 }
 
-func isFraction(v any) (ok bool) {
+func IsFraction(v any) (ok bool) {
 	_, ok = v.(*FractionType)
 	return ok
 }
+
+// func IsFract(v any) (ok bool) {
+// 	_, ok = v.(*FractionType)
+// 	return ok
+// }
+
+func IsRational(v any) (ok bool) {
+	if _, ok = v.(*FractionType); !ok {
+		_, ok = v.(int64)
+	}
+	return ok
+}

kern/function.go

@@ -0,0 +1,278 @@
+// Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
+// All rights reserved.
+
+// function.go
+package kern
+
+import (
+	"fmt"
+	"strconv"
+)
+
+// ---- Function templates
+type FuncTemplate func(ctx ExprContext, name string, args map[string]any) (result any, err error)
+
+type DeepFuncTemplate func(a, b any) (eq bool, err error)
+
+func IsFunctor(v any) (ok bool) {
+	_, ok = v.(Functor)
+	return
+}
+
+// ---- Common functor definition
+type BaseFunctor struct {
+	info ExprFunc
+}
+
+func (functor *BaseFunctor) ToString(opt FmtOpt) (s string) {
+	if functor.info != nil {
+		s = functor.info.ToString(opt)
+	} else {
+		s = "func(){}"
+	}
+	return s
+}
+
+func (functor *BaseFunctor) GetParams() (params []ExprFuncParam) {
+	if functor.info != nil {
+		return functor.info.Params()
+	} else {
+		return []ExprFuncParam{}
+	}
+}
+
+func (functor *BaseFunctor) SetFunc(info ExprFunc) {
+	functor.info = info
+}
+
+func (functor *BaseFunctor) GetFunc() ExprFunc {
+	return functor.info
+}
+
+func (functor *BaseFunctor) GetDefinitionContext() ExprContext {
+	return nil
+}
+
+// ---- Function Parameters
+type paramFlags uint16
+
+const (
+	PfDefault paramFlags = 1 << iota
+	PfOptional
+	PfRepeat
+)
+
+type funcParamInfo struct {
+	name         string
+	flags        paramFlags
+	defaultValue any
+}
+
+func NewFuncParam(name string) ExprFuncParam {
+	return &funcParamInfo{name: name}
+}
+
+func NewFuncParamFlag(name string, flags paramFlags) ExprFuncParam {
+	return &funcParamInfo{name: name, flags: flags}
+}
+
+func NewFuncParamFlagDef(name string, flags paramFlags, defValue any) *funcParamInfo {
+	return &funcParamInfo{name: name, flags: flags, defaultValue: defValue}
+}
+
+func (param *funcParamInfo) Name() string {
+	return param.name
+}
+
+func (param *funcParamInfo) Type() string {
+	return TypeAny
+}
+
+func (param *funcParamInfo) IsDefault() bool {
+	return (param.flags & PfDefault) != 0
+}
+
+func (param *funcParamInfo) IsOptional() bool {
+	return (param.flags & PfOptional) != 0
+}
+
+func (param *funcParamInfo) IsRepeat() bool {
+	return (param.flags & PfRepeat) != 0
+}
+
+func (param *funcParamInfo) DefaultValue() any {
+	return param.defaultValue
+}
+
+func initActualParams(ctx ExprContext, info ExprFunc, callTerm Term) (actualParams map[string]any, err error) {
+	var varArgs []any
+	var varName string
+
+	namedParamsStarted := false
+
+	formalParams := info.Params()
+	actualParams = make(map[string]any, len(formalParams))
+	if callTerm == nil {
+		return
+	}
+
+	childCount := callTerm.GetChildCount()
+	for i := range childCount {
+		tree := callTerm.GetChild(i)
+		// for i, tree := range callTerm.Children() {
+		var paramValue any
+		paramCtx := ctx.Clone()
+		if paramValue, err = tree.Compute(paramCtx); err != nil {
+			break
+		}
+		if paramName, namedParam := GetAssignVarName(tree); namedParam {
+			if info.ParamSpec(paramName) == nil {
+				err = fmt.Errorf("%s(): unknown param %q", info.Name(), paramName)
+				break
+			}
+			actualParams[paramName] = paramValue
+			namedParamsStarted = true
+		} else if !namedParamsStarted {
+			if varArgs != nil {
+				varArgs = append(varArgs, paramValue)
+			} else if i < len(formalParams) {
+				spec := formalParams[i]
+				if spec.IsRepeat() {
+					varArgs = make([]any, 0, childCount-i)
+					varArgs = append(varArgs, paramValue)
+					varName = spec.Name()
+				} else {
+					actualParams[spec.Name()] = paramValue
+				}
+			} else {
+				err = ErrTooManyParams(info.Name(), len(formalParams), childCount)
+				break
+			}
+		} else {
+			err = fmt.Errorf("%s(): positional param nr %d not allowed after named params", info.Name(), i+1)
+			break
+		}
+	}
+	if err == nil {
+		if varArgs != nil {
+			actualParams[varName] = varArgs
+		}
+	}
+	return
+}
+
+// func (info *funcInfo) PrepareCall(name string, actualParams map[string]any) (err error) {
+// 	passedCount := len(actualParams)
+// 	if info.MinArgs() > passedCount {
+// 		err = ErrTooFewParams(name, info.MinArgs(), info.MaxArgs(), passedCount)
+// 		return
+// 	}
+
+// 	if passedCount < len(info.formalParams) {
+// 		for _, p := range info.formalParams {
+// 			if _, exists := actualParams[p.Name()]; !exists {
+// 				if !p.IsDefault() {
+// 					break
+// 				}
+// 				if p.IsRepeat() {
+// 					varArgs := make([]any, 1)
+// 					varArgs[0] = p.DefaultValue()
+// 					actualParams[p.Name()] = varArgs
+// 				} else {
+// 					actualParams[p.Name()] = p.DefaultValue()
+// 				}
+// 			}
+// 		}
+// 	}
+
+// 	if info.MaxArgs() >= 0 && info.MaxArgs() < len(actualParams) {
+// 		err = ErrTooManyParams(name, info.MaxArgs(), len(actualParams))
+// 	}
+// 	return
+// }
+
+// ----- Call a function ---
+
+// func getAssignVarName(t *term) (name string, ok bool) {
+// 	if ok = t.symbol() == SymEqual; ok {
+// 		name = t.children[0].source()
+// 	}
+// 	return
+// }
+
+func GetAssignVarName(t Term) (name string, ok bool) {
+	if ok = t.IsAssign(); ok {
+		name = t.GetChildSource(0)
+	}
+	return
+}
+
+func CallFunctionByTerm(parentCtx ExprContext, name string, callTerm Term) (result any, err error) {
+	var actualParams map[string]any
+	if info, exists := parentCtx.GetFuncInfo(name); exists {
+		if actualParams, err = initActualParams(parentCtx, info, callTerm); err == nil {
+			ctx := info.AllocContext(parentCtx)
+			if err = info.PrepareCall(name, actualParams); err == nil {
+				functor := info.Functor()
+				result, err = functor.InvokeNamed(ctx, name, actualParams)
+				exportObjectsToParent(ctx)
+			}
+		}
+	} else {
+		err = fmt.Errorf("unknown function %s()", name)
+	}
+	return
+}
+
+func CallFunctionByArgs(parentCtx ExprContext, name string, args []any) (result any, err error) {
+	var actualParams map[string]any
+	if info, exists := parentCtx.GetFuncInfo(name); exists {
+		functor := info.Functor()
+		actualParams = BindActualParams(functor, args)
+		ctx := info.AllocContext(parentCtx)
+		if err = info.PrepareCall(name, actualParams); err == nil {
+			result, err = functor.InvokeNamed(ctx, name, actualParams)
+			exportObjectsToParent(ctx)
+		}
+	} else {
+		err = fmt.Errorf("unknown function %s()", name)
+	}
+	return
+}
+
+func CallFunctionByParams(parentCtx ExprContext, name string, actualParams map[string]any) (result any, err error) {
+	//var actualParams map[string]any
+	if info, exists := parentCtx.GetFuncInfo(name); exists {
+		functor := info.Functor()
+		ctx := info.AllocContext(parentCtx)
+		if err = info.PrepareCall(name, actualParams); err == nil {
+			result, err = functor.InvokeNamed(ctx, name, actualParams)
+			exportObjectsToParent(ctx)
+		}
+	} else {
+		err = fmt.Errorf("unknown function %s()", name)
+	}
+	return
+}
+
+func GetParam(args map[string]any, paramName string, paramNum int) (value any, exists bool) {
+	if value, exists = args[paramName]; !exists {
+		if paramNum > 0 && paramNum <= len(args) {
+			value, exists = args["arg"+strconv.Itoa(paramNum)]
+		}
+	}
+	return
+}
+
+func BindActualParams(functor Functor, args []any) (actualParams map[string]any) {
+	formalParams := functor.GetParams()
+	actualParams = make(map[string]any, len(args))
+	for i, arg := range args {
+		if i < len(formalParams) {
+			actualParams[formalParams[i].Name()] = arg
+		} else {
+			actualParams["arg"+strconv.Itoa(i+1)] = arg
+		}
+	}
+	return
+}

kern/iterator.go

@@ -2,7 +2,7 @@
 // All rights reserved.
 
 // iterator.go
-package expr
+package kern
 
 import (
 	// "errors"
@@ -30,8 +30,8 @@ type Iterator interface {
 	fmt.Stringer
 	Next() (item any, err error) // must return io.EOF after the last item
 	Current() (item any, err error)
-	Index() int
-	Count() int
+	Index() int64
+	Count() int64
 	HasOperation(name string) bool
 	CallOperation(name string, args map[string]any) (value any, err error)
 }
@@ -42,10 +42,11 @@ type ExtIterator interface {
 	Clean() error
 }
 
-func errNoOperation(name string) error {
+func ErrNoOperation(name string) error {
 	return fmt.Errorf("no %s() function defined in the data-source", name)
 }
 
-// func errInvalidDataSource() error {
-// 	return errors.New("invalid data-source")
-// }
+func IsIterator(v any) (ok bool) {
+	_, ok = v.(Iterator)
+	return
+}

kern/list-type.go

@@ -2,7 +2,7 @@
 // All rights reserved.
 
 // list-type.go
-package expr
+package kern
 
 import (
 	"fmt"
@@ -12,23 +12,21 @@ import (
 
 type ListType []any
 
-func newListA(listAny ...any) (list *ListType) {
+func IsList(v any) (ok bool) {
+	_, ok = v.(*ListType)
+	return ok
+}
+
+func NewListA(listAny ...any) (list *ListType) {
 	if listAny == nil {
 		listAny = []any{}
 	}
-	return newList(listAny)
-}
-
-func newList(listAny []any) (list *ListType) {
 	return NewList(listAny)
 }
 
 func NewList(listAny []any) (list *ListType) {
 	if listAny != nil {
 		ls := make(ListType, len(listAny))
-		//		for i, item := range listAny {
-		//			ls[i] = item
-		//		}
 		copy(ls, listAny)
 		list = &ls
 	}
@@ -106,22 +104,11 @@ func (ls *ListType) TypeName() string {
 	return "list"
 }
 
-// func (list *ListType) indexDeepCmp(target any) (index int) {
-// 	index = -1
-// 	for i, item := range *list {
-// 		if reflect.DeepEqual(item, target) {
-// 			index = i
-// 			break
-// 		}
-// 	}
-// 	return
-// }
-
-func (ls *ListType) contains(t *ListType) (answer bool) {
+func (ls *ListType) Contains(t *ListType) (answer bool) {
 	if len(*ls) >= len(*t) {
 		answer = true
 		for _, item := range *t {
-			if answer = ls.indexDeepSameCmp(item) >= 0; !answer {
+			if answer = ls.IndexDeepSameCmp(item) >= 0; !answer {
 				break
 			}
 		}
@@ -143,12 +130,12 @@ func (ls1 *ListType) Equals(ls2 ListType) (answer bool) {
 	return
 }
 
-func (list *ListType) indexDeepSameCmp(target any) (index int) {
+func (list *ListType) IndexDeepSameCmp(target any) (index int) {
 	var eq bool
 	var err error
 	index = -1
 	for i, item := range *list {
-		if eq, err = deepSame(item, target, sameContent); err != nil {
+		if eq, err = deepSame(item, target, SameContent); err != nil {
 			break
 		} else if eq {
 			index = i
@@ -158,13 +145,13 @@ func (list *ListType) indexDeepSameCmp(target any) (index int) {
 	return
 }
 
-func sameContent(a, b any) (same bool, err error) {
+func SameContent(a, b any) (same bool, err error) {
 	la, _ := a.(*ListType)
 	lb, _ := b.(*ListType)
 	if len(*la) == len(*lb) {
 		same = true
 		for _, item := range *la {
-			if pos := lb.indexDeepSameCmp(item); pos < 0 {
+			if pos := lb.IndexDeepSameCmp(item); pos < 0 {
 				same = false
 				break
 			}
@@ -173,19 +160,19 @@ func sameContent(a, b any) (same bool, err error) {
 	return
 }
 
-func deepSame(a, b any, deepCmp deepFuncTemplate) (eq bool, err error) {
-	if isNumOrFract(a) && isNumOrFract(b) {
+func deepSame(a, b any, deepCmp DeepFuncTemplate) (eq bool, err error) {
+	if IsNumOrFract(a) && IsNumOrFract(b) {
 		if IsNumber(a) && IsNumber(b) {
 			if IsInteger(a) && IsInteger(b) {
 				li, _ := a.(int64)
 				ri, _ := b.(int64)
 				eq = li == ri
 			} else {
-				eq = numAsFloat(a) == numAsFloat(b)
+				eq = NumAsFloat(a) == NumAsFloat(b)
 			}
 		} else {
 			var cmp int
-			if cmp, err = cmpAnyFract(a, b); err == nil {
+			if cmp, err = CmpAnyFract(a, b); err == nil {
 				eq = cmp == 0
 			}
 		}
@@ -198,7 +185,7 @@ func deepSame(a, b any, deepCmp deepFuncTemplate) (eq bool, err error) {
 	return
 }
 
-func (list *ListType) setItem(index int64, value any) (err error) {
+func (list *ListType) SetItem(index int64, value any) (err error) {
 	if index >= 0 && index < int64(len(*list)) {
 		(*list)[index] = value
 	} else {
@@ -207,6 +194,6 @@ func (list *ListType) setItem(index int64, value any) (err error) {
 	return
 }
 
-func (list *ListType) appendItem(value any) {
+func (list *ListType) AppendItem(value any) {
 	*list = append(*list, value)
 }

kern/number.go

@@ -0,0 +1,88 @@
+// Copyright (c) 2024-2026 Celestino Amoroso (celestino.amoroso@gmail.com).
+// All rights reserved.
+
+// number.go
+package kern
+
+import (
+	"fmt"
+)
+
+func IsInteger(v any) (ok bool) {
+	_, ok = v.(int64)
+	return ok
+}
+
+func IsNumber(v any) (ok bool) {
+	return IsFloat(v) || IsInteger(v)
+}
+
+func IsNumOrFract(v any) (ok bool) {
+	return IsFloat(v) || IsInteger(v) || IsFraction(v)
+}
+
+func IsNumberString(v any) (ok bool) {
+	return IsString(v) || IsNumber(v)
+}
+
+func NumAsFloat(v any) (f float64) {
+	var ok bool
+	if f, ok = v.(float64); !ok {
+		if fract, ok := v.(*FractionType); ok {
+			f = fract.ToFloat()
+		} else {
+			i, _ := v.(int64)
+			f = float64(i)
+		}
+	}
+	return
+}
+
+func AnyInteger(v any) (i int64, ok bool) {
+	ok = true
+	switch intval := v.(type) {
+	case int:
+		i = int64(intval)
+	case uint8:
+		i = int64(intval)
+	case uint16:
+		i = int64(intval)
+	case uint64:
+		i = int64(intval)
+	case uint32:
+		i = int64(intval)
+	case int8:
+		i = int64(intval)
+	case int16:
+		i = int64(intval)
+	case int32:
+		i = int64(intval)
+	case int64:
+		i = intval
+	default:
+		ok = false
+	}
+	return
+}
+
+func ToGoInt(value any, description string) (i int, err error) {
+	if valueInt64, ok := value.(int64); ok {
+		i = int(valueInt64)
+	} else if valueInt, ok := value.(int); ok {
+		i = valueInt
+	} else {
+		err = fmt.Errorf("%s expected integer, got %s (%v)", description, TypeName(value), value)
+	}
+	return
+}
+
+func ToGoInt64(value any, description string) (i int64, err error) {
+	if valueInt64, ok := value.(int64); ok {
+		i = valueInt64
+	} else if valueInt, ok := value.(int); ok {
+		i = int64(valueInt)
+	} else {
+		err = fmt.Errorf("%s expected integer, got %s (%v)", description, TypeName(value), value)
+	}
+	return
+}

kern/string.go

@@ -0,0 +1,23 @@
+// Copyright (c) 2024-2026 Celestino Amoroso (celestino.amoroso@gmail.com).
+// All rights reserved.
+
+// string.go
+package kern
+
+import (
+	"fmt"
+)
+
+func IsString(v any) (ok bool) {
+	_, ok = v.(string)
+	return ok
+}
+
+func ToGoString(value any, description string) (s string, err error) {
+	if s, ok := value.(string); ok {
+		return s, nil
+	} else {
+		err = fmt.Errorf("%s expected string, got %s (%v)", description, TypeName(value), value)
+	}
+	return
+}

kern/term.go

@@ -0,0 +1,21 @@
+// Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
+// All rights reserved.
+
+// term.go
+package kern
+
+import (
+	"fmt"
+)
+
+type Term interface {
+	fmt.Stringer
+	// Children() []Term
+	Source() string
+	GetChildCount() (count int)
+	GetChild(index int) Term
+	GetChildSource(index int) string
+	Compute(ctx ExprContext) (result any, err error)
+	IsAssign() bool
+	Errorf(template string, args ...any) (err error)
+}

list-iterator.go

@@ -7,40 +7,43 @@ package expr
 import (
 	"fmt"
 	"io"
+	"slices"
+
+	"git.portale-stac.it/go-pkg/expr/kern"
 )
 
 type ListIterator struct {
-	a     *ListType
-	count int
-	index int
-	start int
-	stop  int
-	step  int
+	a     *kern.ListType
+	count int64
+	index int64
+	start int64
+	stop  int64
+	step  int64
 }
 
-func NewListIterator(list *ListType, args []any) (it *ListIterator) {
+func NewListIterator(list *kern.ListType, args []any) (it *ListIterator) {
 	var argc int = 0
-	listLen := len(([]any)(*list))
+	listLen := int64(len(([]any)(*list)))
 	if args != nil {
 		argc = len(args)
 	}
 	it = &ListIterator{a: list, count: 0, index: -1, start: 0, stop: listLen - 1, step: 1}
 	if argc >= 1 {
-		if i, err := ToGoInt(args[0], "start index"); err == nil {
+		if i, err := kern.ToGoInt64(args[0], "start index"); err == nil {
 			if i < 0 {
 				i = listLen + i
 			}
 			it.start = i
 		}
 		if argc >= 2 {
-			if i, err := ToGoInt(args[1], "stop index"); err == nil {
+			if i, err := kern.ToGoInt64(args[1], "stop index"); err == nil {
 				if i < 0 {
 					i = listLen + i
 				}
 				it.stop = i
 			}
 			if argc >= 3 {
-				if i, err := ToGoInt(args[2], "step"); err == nil {
+				if i, err := kern.ToGoInt64(args[2], "step"); err == nil {
 					if i < 0 {
 						i = -i
 					}
@@ -58,14 +61,14 @@ func NewListIterator(list *ListType, args []any) (it *ListIterator) {
 }
 
 func NewArrayIterator(array []any) (it *ListIterator) {
-	it = &ListIterator{a: (*ListType)(&array), count: 0, index: -1, start: 0, stop: len(array) - 1, step: 1}
+	it = &ListIterator{a: (*kern.ListType)(&array), count: 0, index: -1, start: 0, stop: int64(len(array)) - 1, step: 1}
 	return
 }
 
 func (it *ListIterator) String() string {
-	var l = 0
+	var l = int64(0)
 	if it.a != nil {
-		l = len(*it.a)
+		l = int64(len(*it.a))
 	}
 	return fmt.Sprintf("$([#%d])", l)
 }
@@ -75,26 +78,27 @@ func (it *ListIterator) TypeName() string {
 }
 
 func (it *ListIterator) HasOperation(name string) bool {
-	yes := name == NextName || name == ResetName || name == IndexName || name == CountName || name == CurrentName
+	//yes := name == expr.NextName || name == expr.ResetName || name == expr.IndexName || name == expr.CountName || name == expr.CurrentName
+	yes := slices.Contains([]string{kern.NextName, kern.ResetName, kern.IndexName, kern.CountName, kern.CurrentName}, name)
 	return yes
 }
 
 func (it *ListIterator) CallOperation(name string, args map[string]any) (v any, err error) {
 	switch name {
-	case NextName:
+	case kern.NextName:
 		v, err = it.Next()
-	case ResetName:
+	case kern.ResetName:
 		err = it.Reset()
-	case CleanName:
+	case kern.CleanName:
 		err = it.Clean()
-	case IndexName:
+	case kern.IndexName:
 		v = int64(it.Index())
-	case CurrentName:
+	case kern.CurrentName:
 		v, err = it.Current()
-	case CountName:
+	case kern.CountName:
 		v = it.count
 	default:
-		err = errNoOperation(name)
+		err = kern.ErrNoOperation(name)
 	}
 	return
 }
@@ -102,13 +106,13 @@ func (it *ListIterator) CallOperation(name string, args map[string]any) (v any,
 func (it *ListIterator) Current() (item any, err error) {
 	a := *(it.a)
 	if it.start <= it.stop {
-		if it.stop < len(a) && it.index >= it.start && it.index <= it.stop {
+		if it.stop < int64(len(a)) && it.index >= it.start && it.index <= it.stop {
 			item = a[it.index]
 		} else {
 			err = io.EOF
 		}
 	} else {
-		if it.start < len(a) && it.index >= it.stop && it.index <= it.start {
+		if it.start < int64(len(a)) && it.index >= it.stop && it.index <= it.start {
 			item = a[it.index]
 		} else {
 			err = io.EOF
@@ -126,11 +130,11 @@ func (it *ListIterator) Next() (item any, err error) {
 	return
 }
 
-func (it *ListIterator) Index() int {
+func (it *ListIterator) Index() int64 {
 	return it.index
 }
 
-func (it *ListIterator) Count() int {
+func (it *ListIterator) Count() int64 {
 	return it.count
 }
 

operand-dict.go

@@ -4,6 +4,9 @@
 // operand-dict.go
 package expr
 
+import (
+	"git.portale-stac.it/go-pkg/expr/kern"
+)
 
 // -------- dict term
 func newDictTerm(args map[any]*term) *term {
@@ -18,12 +21,12 @@ func newDictTerm(args map[any]*term) *term {
 }
 
 // -------- dict func
-func evalDict(ctx ExprContext, opTerm *term) (v any, err error) {
+func evalDict(ctx kern.ExprContext, opTerm *term) (v any, err error) {
 	dict, _ := opTerm.value().(map[any]*term)
-	items := make(DictType, len(dict))
+	items := make(kern.DictType, len(dict))
 	for key, tree := range dict {
 		var param any
-		if param, err = tree.compute(ctx); err != nil {
+		if param, err = tree.Compute(ctx); err != nil {
 			break
 		}
 		items[key] = param

operand-expr.go

@@ -4,11 +4,15 @@
 // operand-expr.go
 package expr
 
-import "fmt"
+import (
+	"fmt"
+
+	"git.portale-stac.it/go-pkg/expr/kern"
+)
 
 // -------- expr term
 func newExprTerm(root *term) *term {
-	tk := NewValueToken(root.tk.row, root.tk.col, SymExpression, root.source(), root)
+	tk := NewValueToken(root.tk.row, root.tk.col, SymExpression, root.Source(), root)
 	return &term{
 		tk:       *tk,
 		parent:   nil,
@@ -20,9 +24,9 @@ func newExprTerm(root *term) *term {
 }
 
 // -------- eval expr
-func evalExpr(ctx ExprContext, opTerm *term) (v any, err error) {
-	if expr, ok := opTerm.value().(*term); ok {
-		v, err = expr.compute(ctx)
+func evalExpr(ctx kern.ExprContext, opTerm *term) (v any, err error) {
+	if ast, ok := opTerm.value().(*term); ok {
+		v, err = ast.Compute(ctx)
 	} else {
 		err = fmt.Errorf("expression expected, got %T", opTerm.value())
 	}

operand-func.go

@@ -6,15 +6,21 @@ package expr
 
 import (
 	"errors"
+
+	"git.portale-stac.it/go-pkg/expr/kern"
 )
 
 // -------- function call term
 func newFuncCallTerm(tk *Token, args []*term) *term {
+	var pos termPosition = posLeaf
+	if len(args) > 0 {
+		pos = posMultifix
+	}
 	return &term{
 		tk:       *tk,
 		parent:   nil,
 		children: args,
-		position: posLeaf,
+		position: pos,
 		priority: priValue,
 		evalFunc: evalFuncCall,
 	}
@@ -38,9 +44,9 @@ func newFuncCallTerm(tk *Token, args []*term) *term {
 // 	return
 // }
 
-func evalFuncCall(ctx ExprContext, opTerm *term) (v any, err error) {
+func evalFuncCall(ctx kern.ExprContext, opTerm *term) (v any, err error) {
 	name, _ := opTerm.tk.Value.(string)
-	v, err = CallFunctionByTerm(ctx, name, opTerm)
+	v, err = kern.CallFunctionByTerm(ctx, name, opTerm)
 	return
 }
 
@@ -57,23 +63,23 @@ func newFuncDefTerm(tk *Token, args []*term) *term {
 }
 
 // -------- eval func def
-func evalFuncDef(ctx ExprContext, opTerm *term) (v any, err error) {
+func evalFuncDef(ctx kern.ExprContext, opTerm *term) (v any, err error) {
 	bodySpec := opTerm.value()
-	if expr, ok := bodySpec.(*ast); ok {
-		paramList := make([]ExprFuncParam, 0, len(opTerm.children))
+	if ast, ok := bodySpec.(*ast); ok {
+		paramList := make([]kern.ExprFuncParam, 0, len(opTerm.children))
 		for _, param := range opTerm.children {
 			var defValue any
 			flags := paramFlags(0)
 			if len(param.children) > 0 {
 				flags |= PfDefault
-				if defValue, err = param.children[0].compute(ctx); err != nil {
+				if defValue, err = param.children[0].Compute(ctx); err != nil {
 					return
 				}
 			}
-			info := NewFuncParamFlagDef(param.source(), flags, defValue)
+			info := NewFuncParamFlagDef(param.Source(), flags, defValue)
 			paramList = append(paramList, info)
 		}
-		v = newExprFunctor(expr, paramList, ctx)
+		v = newExprFunctor(ast, paramList, ctx)
 	} else {
 		err = errors.New("invalid function definition: the body specification must be an expression")
 	}

operand-iterator.go

@@ -7,6 +7,8 @@ package expr
 import (
 	"slices"
 	"strings"
+
+	"git.portale-stac.it/go-pkg/expr/kern"
 )
 
 // -------- iterator term
@@ -25,11 +27,11 @@ func newIteratorTerm(tk *Token, args []*term) *term {
 
 // -------- eval iterator
 
-func evalTermArray(ctx ExprContext, terms []*term) (values []any, err error) {
+func evalTermArray(ctx kern.ExprContext, terms []*term) (values []any, err error) {
 	values = make([]any, len(terms))
 	for i, t := range terms {
 		var value any
-		if value, err = t.compute(ctx); err == nil {
+		if value, err = t.Compute(ctx); err == nil {
 			values[i] = value
 		} else {
 			break
@@ -38,25 +40,25 @@ func evalTermArray(ctx ExprContext, terms []*term) (values []any, err error) {
 	return
 }
 
-func evalFirstChild(ctx ExprContext, iteratorTerm *term) (value any, err error) {
+func evalFirstChild(ctx kern.ExprContext, iteratorTerm *term) (value any, err error) {
 	if len(iteratorTerm.children) < 1 || iteratorTerm.children[0] == nil {
 		err = iteratorTerm.Errorf("missing the data-source parameter")
 		return
 	}
 
-	value, err = iteratorTerm.children[0].compute(ctx)
+	value, err = iteratorTerm.children[0].Compute(ctx)
 	return
 }
 
-func getDataSourceDict(iteratorTerm *term, firstChildValue any) (ds map[string]Functor, err error) {
-	if dictAny, ok := firstChildValue.(*DictType); ok {
-		requiredFields := []string{NextName}
+func getDataSourceDict(iteratorTerm *term, firstChildValue any) (ds map[string]kern.Functor, err error) {
+	if dictAny, ok := firstChildValue.(*kern.DictType); ok {
+		requiredFields := []string{kern.NextName}
 		fieldsMask := 0b1
 		foundFields := 0
-		ds = make(map[string]Functor)
+		ds = make(map[string]kern.Functor)
 		for keyAny, item := range *dictAny {
 			if key, ok := keyAny.(string); ok {
-				if functor, ok := item.(Functor); ok {
+				if functor, ok := item.(kern.Functor); ok {
 					ds[key] = functor
 					if index := slices.Index(requiredFields, key); index >= 0 {
 						foundFields |= 1 << index
@@ -78,9 +80,9 @@ func getDataSourceDict(iteratorTerm *term, firstChildValue any) (ds map[string]F
 	return
 }
 
-func evalIterator(ctx ExprContext, opTerm *term) (v any, err error) {
+func evalIterator(ctx kern.ExprContext, opTerm *term) (v any, err error) {
 	var firstChildValue any
-	var ds map[string]Functor
+	var ds map[string]kern.Functor
 
 	if firstChildValue, err = evalFirstChild(ctx, opTerm); err != nil {
 		return
@@ -95,7 +97,7 @@ func evalIterator(ctx ExprContext, opTerm *term) (v any, err error) {
 		if len(ds) > 0 {
 			var dc *dataCursor
 			dcCtx := ctx.Clone()
-			if initFunc, exists := ds[InitName]; exists && initFunc != nil {
+			if initFunc, exists := ds[kern.InitName]; exists && initFunc != nil {
 				var args []any
 				var resource any
 				if len(opTerm.children) > 1 {
@@ -106,13 +108,13 @@ func evalIterator(ctx ExprContext, opTerm *term) (v any, err error) {
 					args = []any{}
 				}
 
-				actualParams := bindActualParams(initFunc, args)
+				actualParams := kern.BindActualParams(initFunc, args)
 
 				initCtx := ctx.Clone()
-				if resource, err = initFunc.InvokeNamed(initCtx, InitName, actualParams); err != nil {
+				if resource, err = initFunc.InvokeNamed(initCtx, kern.InitName, actualParams); err != nil {
 					return
 				}
-				exportObjects(dcCtx, initCtx)
+				kern.ExportObjects(dcCtx, initCtx)
 				dc = NewDataCursor(dcCtx, ds, resource)
 			} else {
 				dc = NewDataCursor(dcCtx, ds, nil)
@@ -120,7 +122,7 @@ func evalIterator(ctx ExprContext, opTerm *term) (v any, err error) {
 
 			v = dc
 		} else {
-			if dictIt, ok := firstChildValue.(*DictType); ok {
+			if dictIt, ok := firstChildValue.(*kern.DictType); ok {
 				var args []any
 				if args, err = evalSibling(ctx, opTerm.children, nil); err == nil {
 					v, err = NewDictIterator(dictIt, args)
@@ -129,11 +131,16 @@ func evalIterator(ctx ExprContext, opTerm *term) (v any, err error) {
 				err = opTerm.children[0].Errorf("the data-source must be a dictionary")
 			}
 		}
-	} else if list, ok := firstChildValue.(*ListType); ok {
+	} else if list, ok := firstChildValue.(*kern.ListType); ok {
 		var args []any
 		if args, err = evalSibling(ctx, opTerm.children, nil); err == nil {
 			v = NewListIterator(list, args)
 		}
+	} else if intVal, ok := firstChildValue.(int64); ok {
+		var args []any
+		if args, err = evalSibling(ctx, opTerm.children, intVal); err == nil {
+			v, err = NewIntIterator(args)
+		}
 	} else {
 		var list []any
 		if list, err = evalSibling(ctx, opTerm.children, firstChildValue); err == nil {
@@ -143,7 +150,7 @@ func evalIterator(ctx ExprContext, opTerm *term) (v any, err error) {
 	return
 }
 
-func evalSibling(ctx ExprContext, terms []*term, firstChildValue any) (list []any, err error) {
+func evalSibling(ctx kern.ExprContext, terms []*term, firstChildValue any) (list []any, err error) {
 	items := make([]any, 0, len(terms))
 	for i, tree := range terms {
 		var param any
@@ -152,7 +159,7 @@ func evalSibling(ctx ExprContext, terms []*term, firstChildValue any) (list []an
 				continue
 			}
 			param = firstChildValue
-		} else if param, err = tree.compute(ctx); err != nil {
+		} else if param, err = tree.Compute(ctx); err != nil {
 			break
 		}
 		items = append(items, param)

operand-list.go

@@ -4,6 +4,10 @@
 // operand-list.go
 package expr
 
+import (
+	"git.portale-stac.it/go-pkg/expr/kern"
+)
+
 // -------- list term
 func newListTermA(args ...*term) *term {
 	return newListTerm(0, 0, args)
@@ -21,12 +25,12 @@ func newListTerm(row, col int, args []*term) *term {
 }
 
 // -------- list func
-func evalList(ctx ExprContext, opTerm *term) (v any, err error) {
+func evalList(ctx kern.ExprContext, opTerm *term) (v any, err error) {
 	list, _ := opTerm.value().([]*term)
-	items := make(ListType, len(list))
+	items := make(kern.ListType, len(list))
 	for i, tree := range list {
 		var param any
-		if param, err = tree.compute(ctx); err != nil {
+		if param, err = tree.Compute(ctx); err != nil {
 			break
 		}
 		items[i] = param

operand-literal.go

@@ -4,6 +4,10 @@
 // operand-literal.go
 package expr
 
+import (
+	"git.portale-stac.it/go-pkg/expr/kern"
+)
+
 // -------- literal term
 func newLiteralTerm(tk *Token) *term {
 	return &term{
@@ -17,7 +21,7 @@ func newLiteralTerm(tk *Token) *term {
 }
 
 // -------- eval func
-func evalLiteral(ctx ExprContext, opTerm *term) (v any, err error) {
+func evalLiteral(ctx kern.ExprContext, opTerm *term) (v any, err error) {
 	v = opTerm.tk.Value
 	return
 }

operand-selector-case.go

@@ -7,6 +7,8 @@ package expr
 import (
 	"fmt"
 	"strings"
+
+	"git.portale-stac.it/go-pkg/expr/kern"
 )
 
 // -------- selector case term
@@ -41,7 +43,7 @@ func newSelectorCaseTerm(row, col int, filterList *term, caseExpr Expr) *term {
 }
 
 // -------- eval selector case
-func evalSelectorCase(ctx ExprContext, opTerm *term) (v any, err error) {
+func evalSelectorCase(ctx kern.ExprContext, opTerm *term) (v any, err error) {
 	var ok bool
 	if v, ok = opTerm.value().(*selectorCase); !ok {
 		err = fmt.Errorf("selector-case expected, got %T", opTerm.value())

operand-var.go

@@ -4,7 +4,11 @@
 // operand-var.go
 package expr
 
-import "fmt"
+import (
+	"fmt"
+
+	"git.portale-stac.it/go-pkg/expr/kern"
+)
 
 // -------- variable term
 func newVarTerm(tk *Token) *term {
@@ -21,11 +25,11 @@ func newVarTerm(tk *Token) *term {
 }
 
 // -------- eval func
-func evalVar(ctx ExprContext, opTerm *term) (v any, err error) {
+func evalVar(ctx kern.ExprContext, opTerm *term) (v any, err error) {
 	var exists bool
-	name := opTerm.source()
-	if v, exists = GetVar(ctx, name); !exists {
-		if info, exists := GetFuncInfo(ctx, name); exists {
+	name := opTerm.Source()
+	if v, exists = ctx.GetVar(name); !exists {
+		if info, exists := ctx.GetFuncInfo(name); exists {
 			v = info.Functor()
 		} else {
 			err = fmt.Errorf("undefined variable or function %q", name)

operator-assign.go

@@ -4,6 +4,11 @@
 // operator-assign.go
 package expr
 
+import (
+	"git.portale-stac.it/go-pkg/expr/kern"
+	"git.portale-stac.it/go-pkg/expr/util"
+)
+
 //-------- assign term
 
 func newAssignTerm(tk *Token) (inst *term) {
@@ -16,19 +21,19 @@ func newAssignTerm(tk *Token) (inst *term) {
 	}
 }
 
-func assignCollectionItem(ctx ExprContext, collectionTerm, keyListTerm *term, value any) (err error) {
+func assignCollectionItem(ctx kern.ExprContext, collectionTerm, keyListTerm *term, value any) (err error) {
 	var collectionValue, keyListValue, keyValue any
-	var keyList *ListType
+	var keyList *kern.ListType
 	var ok bool
 
-	if collectionValue, err = collectionTerm.compute(ctx); err != nil {
+	if collectionValue, err = collectionTerm.Compute(ctx); err != nil {
 		return
 	}
 
-	if keyListValue, err = keyListTerm.compute(ctx); err != nil {
+	if keyListValue, err = keyListTerm.Compute(ctx); err != nil {
 		return
-	} else if keyList, ok = keyListValue.(*ListType); !ok || len(*keyList) != 1 {
-		err = keyListTerm.Errorf("index/key specification expected, got %v [%s]", keyListValue, TypeName(keyListValue))
+	} else if keyList, ok = keyListValue.(*kern.ListType); !ok || len(*keyList) != 1 {
+		err = keyListTerm.Errorf("index/key specification expected, got %v [%s]", keyListValue, kern.TypeName(keyListValue))
 		return
 	}
 	if keyValue = (*keyList)[0]; keyValue == nil {
@@ -37,30 +42,30 @@ func assignCollectionItem(ctx ExprContext, collectionTerm, keyListTerm *term, va
 	}
 
 	switch collection := collectionValue.(type) {
-	case *ListType:
+	case *kern.ListType:
 		if index, ok := keyValue.(int64); ok {
-			err = collection.setItem(index, value)
+			err = collection.SetItem(index, value)
 		} else {
-			err = keyListTerm.Errorf("integer expected, got %v [%s]", keyValue, TypeName(keyValue))
+			err = keyListTerm.Errorf("integer expected, got %v [%s]", keyValue, kern.TypeName(keyValue))
 		}
-	case *DictType:
-		err = collection.setItem(keyValue, value)
+	case *kern.DictType:
+		err = collection.SetItem(keyValue, value)
 	default:
 		err = collectionTerm.Errorf("collection expected")
 	}
 	return
 }
 
-func assignValue(ctx ExprContext, leftTerm *term, v any) (err error) {
+func assignValue(ctx kern.ExprContext, leftTerm *term, v any) (err error) {
 	if leftTerm.symbol() == SymIndex {
 		err = assignCollectionItem(ctx, leftTerm.children[0], leftTerm.children[1], v)
 	} else {
-		ctx.UnsafeSetVar(leftTerm.source(), v)
+		ctx.UnsafeSetVar(leftTerm.Source(), v)
 	}
 	return
 }
 
-func evalAssign(ctx ExprContext, opTerm *term) (v any, err error) {
+func evalAssign(ctx kern.ExprContext, opTerm *term) (v any, err error) {
 	if err = opTerm.checkOperands(); err != nil {
 		return
 	}
@@ -74,17 +79,17 @@ func evalAssign(ctx ExprContext, opTerm *term) (v any, err error) {
 
 	rightChild := opTerm.children[1]
 
-	if v, err = rightChild.compute(ctx); err == nil {
-		if functor, ok := v.(Functor); ok {
+	if v, err = rightChild.Compute(ctx); err == nil {
+		if functor, ok := v.(kern.Functor); ok {
 			if leftSym == SymVariable {
 				if info := functor.GetFunc(); info != nil {
-					ctx.RegisterFunc(leftTerm.source(), info.Functor(), info.ReturnType(), info.Params())
+					ctx.RegisterFunc(leftTerm.Source(), info.Functor(), info.ReturnType(), info.Params())
 				} else if funcDef, ok := functor.(*exprFunctor); ok {
-					paramSpecs := ForAll(funcDef.params, func(p ExprFuncParam) ExprFuncParam { return p })
+					paramSpecs := util.ForAll(funcDef.params, func(p kern.ExprFuncParam) kern.ExprFuncParam { return p })
 
-					ctx.RegisterFunc(leftTerm.source(), functor, TypeAny, paramSpecs)
+					ctx.RegisterFunc(leftTerm.Source(), functor, kern.TypeAny, paramSpecs)
 				} else {
-					err = opTerm.Errorf("unknown function %s()", rightChild.source())
+					err = opTerm.Errorf("unknown function %s()", rightChild.Source())
 				}
 			} else {
 				err = assignValue(ctx, leftTerm, v)
@@ -111,19 +116,19 @@ func newOpAssignTerm(tk *Token) (inst *term) {
 	}
 }
 
-func getCollectionItemValue(ctx ExprContext, collectionTerm, keyListTerm *term) (value any, err error) {
+func getCollectionItemValue(ctx kern.ExprContext, collectionTerm, keyListTerm *term) (value any, err error) {
 	var collectionValue, keyListValue, keyValue any
-	var keyList *ListType
+	var keyList *kern.ListType
 	var ok bool
 
-	if collectionValue, err = collectionTerm.compute(ctx); err != nil {
+	if collectionValue, err = collectionTerm.Compute(ctx); err != nil {
 		return
 	}
 
-	if keyListValue, err = keyListTerm.compute(ctx); err != nil {
+	if keyListValue, err = keyListTerm.Compute(ctx); err != nil {
 		return
-	} else if keyList, ok = keyListValue.(*ListType); !ok || len(*keyList) != 1 {
-		err = keyListTerm.Errorf("index/key specification expected, got %v [%s]", keyListValue, TypeName(keyListValue))
+	} else if keyList, ok = keyListValue.(*kern.ListType); !ok || len(*keyList) != 1 {
+		err = keyListTerm.Errorf("index/key specification expected, got %v [%s]", keyListValue, kern.TypeName(keyListValue))
 		return
 	}
 	if keyValue = (*keyList)[0]; keyValue == nil {
@@ -132,13 +137,13 @@ func getCollectionItemValue(ctx ExprContext, collectionTerm, keyListTerm *term)
 	}
 
 	switch collection := collectionValue.(type) {
-	case *ListType:
+	case *kern.ListType:
 		if index, ok := keyValue.(int64); ok {
 			value = (*collection)[index]
 		} else {
-			err = keyListTerm.Errorf("integer expected, got %v [%s]", keyValue, TypeName(keyValue))
+			err = keyListTerm.Errorf("integer expected, got %v [%s]", keyValue, kern.TypeName(keyValue))
 		}
-	case *DictType:
+	case *kern.DictType:
 		value = (*collection)[keyValue]
 	default:
 		err = collectionTerm.Errorf("collection expected")
@@ -146,16 +151,16 @@ func getCollectionItemValue(ctx ExprContext, collectionTerm, keyListTerm *term)
 	return
 }
 
-func getAssignValue(ctx ExprContext, leftTerm *term) (value any, err error) {
+func getAssignValue(ctx kern.ExprContext, leftTerm *term) (value any, err error) {
 	if leftTerm.symbol() == SymIndex {
 		value, err = getCollectionItemValue(ctx, leftTerm.children[0], leftTerm.children[1])
 	} else {
-		value, _ = ctx.GetVar(leftTerm.source())
+		value, _ = ctx.GetVar(leftTerm.Source())
 	}
 	return
 }
 
-func evalOpAssign(ctx ExprContext, opTerm *term) (v any, err error) {
+func evalOpAssign(ctx kern.ExprContext, opTerm *term) (v any, err error) {
 	var rightValue, leftValue any
 	if err = opTerm.checkOperands(); err != nil {
 		return
@@ -170,7 +175,7 @@ func evalOpAssign(ctx ExprContext, opTerm *term) (v any, err error) {
 
 	rightChild := opTerm.children[1]
 
-	if rightValue, err = rightChild.compute(ctx); err == nil {
+	if rightValue, err = rightChild.Compute(ctx); err == nil {
 		if leftValue, err = getAssignValue(ctx, leftTerm); err == nil {
 			switch opTerm.symbol() {
 			case SymPlusEqual:
@@ -194,7 +199,7 @@ func evalOpAssign(ctx ExprContext, opTerm *term) (v any, err error) {
 			case SymDoubleGreaterEqual:
 				v, err = bitRightShift(opTerm, leftValue, rightValue)
 			default:
-				err = opTerm.Errorf("unsupported assign operator %q", opTerm.source())
+				err = opTerm.Errorf("unsupported assign operator %q", opTerm.Source())
 			}
 			if err == nil {
 				err = assignValue(ctx, leftTerm, v)

operator-bitwise.go

@@ -4,6 +4,10 @@
 // operator-bitwise.go
 package expr
 
+import (
+	"git.portale-stac.it/go-pkg/expr/kern"
+)
+
 //-------- Bitwise NOT term
 
 func newBitwiseNotTerm(tk *Token) (inst *term) {
@@ -16,18 +20,18 @@ func newBitwiseNotTerm(tk *Token) (inst *term) {
 	}
 }
 
-func evalBitwiseNot(ctx ExprContext, opTerm *term) (v any, err error) {
+func evalBitwiseNot(ctx kern.ExprContext, opTerm *term) (v any, err error) {
 	var value any
 
 	if value, err = opTerm.evalPrefix(ctx); err != nil {
 		return
 	}
 
-	if IsInteger(value) {
+	if kern.IsInteger(value) {
 		i, _ := value.(int64)
 		v = ^i
 	} else {
-		err = opTerm.errIncompatibleType(value)
+		err = opTerm.errIncompatiblePrefixPostfixType(value)
 	}
 	return
 }
@@ -59,7 +63,7 @@ func bitwiseAnd(opTerm *term, leftValue, rightValue any) (v any, err error) {
 	return
 }
 
-func evalBitwiseAnd(ctx ExprContext, opTerm *term) (v any, err error) {
+func evalBitwiseAnd(ctx kern.ExprContext, opTerm *term) (v any, err error) {
 	var leftValue, rightValue any
 
 	if leftValue, rightValue, err = opTerm.evalInfix(ctx); err != nil {
@@ -96,7 +100,7 @@ func bitwiseOr(opTerm *term, leftValue, rightValue any) (v any, err error) {
 	return
 }
 
-func evalBitwiseOr(ctx ExprContext, opTerm *term) (v any, err error) {
+func evalBitwiseOr(ctx kern.ExprContext, opTerm *term) (v any, err error) {
 	var leftValue, rightValue any
 
 	if leftValue, rightValue, err = opTerm.evalInfix(ctx); err != nil {
@@ -134,7 +138,7 @@ func bitwiseXor(opTerm *term, leftValue, rightValue any) (v any, err error) {
 	return
 }
 
-func evalBitwiseXor(ctx ExprContext, opTerm *term) (v any, err error) {
+func evalBitwiseXor(ctx kern.ExprContext, opTerm *term) (v any, err error) {
 	var leftValue, rightValue any
 
 	if leftValue, rightValue, err = opTerm.evalInfix(ctx); err != nil {

operator-bool.go

@@ -4,7 +4,11 @@
 // operator-bool.go
 package expr
 
-import "fmt"
+import (
+	"fmt"
+
+	"git.portale-stac.it/go-pkg/expr/kern"
+)
 
 //-------- NOT term
 
@@ -18,17 +22,17 @@ func newNotTerm(tk *Token) (inst *term) {
 	}
 }
 
-func evalNot(ctx ExprContext, opTerm *term) (v any, err error) {
+func evalNot(ctx kern.ExprContext, opTerm *term) (v any, err error) {
 	var rightValue any
 
 	if rightValue, err = opTerm.evalPrefix(ctx); err != nil {
 		return
 	}
 
-	if b, ok := ToBool(rightValue); ok {
+	if b, ok := kern.ToBool(rightValue); ok {
 		v = !b
 	} else {
-		err = opTerm.errIncompatibleType(rightValue)
+		err = opTerm.errIncompatiblePrefixPostfixType(rightValue)
 	}
 	return
 }
@@ -45,8 +49,8 @@ func newAndTerm(tk *Token) (inst *term) {
 	}
 }
 
-func evalAnd(ctx ExprContext, self *term) (v any, err error) {
-	if CtrlIsEnabled(ctx, ControlBoolShortcut) {
+func evalAnd(ctx kern.ExprContext, self *term) (v any, err error) {
+	if kern.CtrlIsEnabled(ctx, kern.ControlBoolShortcut) {
 		v, err = evalAndWithShortcut(ctx, self)
 	} else {
 		v, err = evalAndWithoutShortcut(ctx, self)
@@ -54,7 +58,7 @@ func evalAnd(ctx ExprContext, self *term) (v any, err error) {
 	return
 }
 
-func evalAndWithoutShortcut(ctx ExprContext, self *term) (v any, err error) {
+func evalAndWithoutShortcut(ctx kern.ExprContext, self *term) (v any, err error) {
 	var leftValue, rightValue any
 	var leftBool, rightBool bool
 	var lok, rok bool
@@ -63,8 +67,8 @@ func evalAndWithoutShortcut(ctx ExprContext, self *term) (v any, err error) {
 		return
 	}
 
-	leftBool, lok = ToBool(leftValue)
-	rightBool, rok = ToBool(rightValue)
+	leftBool, lok = kern.ToBool(leftValue)
+	rightBool, rok = kern.ToBool(rightValue)
 
 	if lok && rok {
 		v = leftBool && rightBool
@@ -74,24 +78,25 @@ func evalAndWithoutShortcut(ctx ExprContext, self *term) (v any, err error) {
 	return
 }
 
-func evalAndWithShortcut(ctx ExprContext, self *term) (v any, err error) {
+func evalAndWithShortcut(ctx kern.ExprContext, self *term) (v any, err error) {
 	var leftValue, rightValue any
 
 	if err = self.checkOperands(); err != nil {
 		return
 	}
 
-	if leftValue, err = self.children[0].compute(ctx); err != nil {
+	if leftValue, err = self.children[0].Compute(ctx); err != nil {
 		return
 	}
 
-	if leftBool, lok := ToBool(leftValue); !lok {
-		err = fmt.Errorf("got %s as left operand type of 'AND' operator, it must be bool", TypeName(leftValue))
-		return
+	if leftBool, lok := kern.ToBool(leftValue); !lok {
+		// err = fmt.Errorf("got %s as left operand type of 'AND' operator, it must be bool", expr.TypeName(leftValue))
+		// return
+		err = self.errIncompatibleType(leftValue, "left")
 	} else if !leftBool {
 		v = false
-	} else if rightValue, err = self.children[1].compute(ctx); err == nil {
-		if rightBool, rok := ToBool(rightValue); rok {
+	} else if rightValue, err = self.children[1].Compute(ctx); err == nil {
+		if rightBool, rok := kern.ToBool(rightValue); rok {
 			v = rightBool
 		} else {
 			err = self.errIncompatibleTypes(leftValue, rightValue)
@@ -112,8 +117,8 @@ func newOrTerm(tk *Token) (inst *term) {
 	}
 }
 
-func evalOr(ctx ExprContext, self *term) (v any, err error) {
-	if CtrlIsEnabled(ctx, ControlBoolShortcut) {
+func evalOr(ctx kern.ExprContext, self *term) (v any, err error) {
+	if kern.CtrlIsEnabled(ctx, kern.ControlBoolShortcut) {
 		v, err = evalOrWithShortcut(ctx, self)
 	} else {
 		v, err = evalOrWithoutShortcut(ctx, self)
@@ -121,7 +126,7 @@ func evalOr(ctx ExprContext, self *term) (v any, err error) {
 	return
 }
 
-func evalOrWithoutShortcut(ctx ExprContext, self *term) (v any, err error) {
+func evalOrWithoutShortcut(ctx kern.ExprContext, self *term) (v any, err error) {
 	var leftValue, rightValue any
 	var leftBool, rightBool bool
 	var lok, rok bool
@@ -130,8 +135,8 @@ func evalOrWithoutShortcut(ctx ExprContext, self *term) (v any, err error) {
 		return
 	}
 
-	leftBool, lok = ToBool(leftValue)
-	rightBool, rok = ToBool(rightValue)
+	leftBool, lok = kern.ToBool(leftValue)
+	rightBool, rok = kern.ToBool(rightValue)
 
 	if lok && rok {
 		v = leftBool || rightBool
@@ -141,24 +146,24 @@ func evalOrWithoutShortcut(ctx ExprContext, self *term) (v any, err error) {
 	return
 }
 
-func evalOrWithShortcut(ctx ExprContext, self *term) (v any, err error) {
+func evalOrWithShortcut(ctx kern.ExprContext, self *term) (v any, err error) {
 	var leftValue, rightValue any
 
 	if err = self.checkOperands(); err != nil {
 		return
 	}
 
-	if leftValue, err = self.children[0].compute(ctx); err != nil {
+	if leftValue, err = self.children[0].Compute(ctx); err != nil {
 		return
 	}
 
-	if leftBool, lok := ToBool(leftValue); !lok {
-		err = fmt.Errorf("got %s as left operand type of 'OR' operator, it must be bool", TypeName(leftValue))
+	if leftBool, lok := kern.ToBool(leftValue); !lok {
+		err = fmt.Errorf("got %s as left operand type of 'OR' operator, it must be bool", kern.TypeName(leftValue))
 		return
 	} else if leftBool {
 		v = true
-	} else if rightValue, err = self.children[1].compute(ctx); err == nil {
-		if rightBool, rok := ToBool(rightValue); rok {
+	} else if rightValue, err = self.children[1].Compute(ctx); err == nil {
+		if rightBool, rok := kern.ToBool(rightValue); rok {
 			v = rightBool
 		} else {
 			err = self.errIncompatibleTypes(leftValue, rightValue)

operator-builtin.go

@@ -4,7 +4,11 @@
 // operator-builtin.go
 package expr
 
-import "io"
+import (
+	"io"
+
+	"git.portale-stac.it/go-pkg/expr/kern"
+)
 
 //-------- builtin term
 
@@ -18,7 +22,7 @@ func newBuiltinTerm(tk *Token) (inst *term) {
 	}
 }
 
-func evalBuiltin(ctx ExprContext, opTerm *term) (v any, err error) {
+func evalBuiltin(ctx kern.ExprContext, opTerm *term) (v any, err error) {
 	var childValue any
 
 	if childValue, err = opTerm.evalPrefix(ctx); err != nil {
@@ -26,25 +30,25 @@ func evalBuiltin(ctx ExprContext, opTerm *term) (v any, err error) {
 	}
 
 	count := 0
-	if IsString(childValue) {
+	if kern.IsString(childValue) {
 		module, _ := childValue.(string)
-		count, err = ImportInContextByGlobPattern(module)
+		count, err = ImportInContextByGlobPattern(ctx, module)
 	} else {
 		var moduleSpec any
-		var it Iterator
+		var it kern.Iterator
 		if it, err = NewIterator(childValue); err != nil {
 			return
 		}
 		for moduleSpec, err = it.Next(); err == nil; moduleSpec, err = it.Next() {
 			if module, ok := moduleSpec.(string); ok {
-				if ImportInContext(module) {
+				if ImportInContext(ctx, module) {
 					count++
 				} else {
 					err = opTerm.Errorf("unknown builtin module %q", module)
 					break
 				}
 			} else {
-				err = opTerm.Errorf("expected string at item nr %d, got %s", it.Index()+1, TypeName(moduleSpec))
+				err = opTerm.Errorf("expected string at item nr %d, got %s", it.Index()+1, kern.TypeName(moduleSpec))
 				break
 			}
 		}

operator-but.go

@@ -4,6 +4,10 @@
 // operator-but.go
 package expr
 
+import (
+	"git.portale-stac.it/go-pkg/expr/kern"
+)
+
 //-------- but term
 
 func newButTerm(tk *Token) (inst *term) {
@@ -16,7 +20,7 @@ func newButTerm(tk *Token) (inst *term) {
 	}
 }
 
-func evalBut(ctx ExprContext, opTerm *term) (v any, err error) {
+func evalBut(ctx kern.ExprContext, opTerm *term) (v any, err error) {
 	_, v, err = opTerm.evalInfix(ctx)
 	return
 }

operator-context.go

@@ -4,6 +4,10 @@
 // operator-context-value.go
 package expr
 
+import (
+	"git.portale-stac.it/go-pkg/expr/kern"
+)
+
 //-------- context term
 
 func newContextTerm(tk *Token) (inst *term) {
@@ -16,14 +20,14 @@ func newContextTerm(tk *Token) (inst *term) {
 	}
 }
 
-func evalContextValue(ctx ExprContext, opTerm *term) (v any, err error) {
+func evalContextValue(ctx kern.ExprContext, opTerm *term) (v any, err error) {
 	var childValue any
 
-	var sourceCtx ExprContext
+	var sourceCtx kern.ExprContext
 	if len(opTerm.children) == 0 {
 		sourceCtx = ctx
-	} else if opTerm.children[0].symbol() == SymVariable && opTerm.children[0].source() == "global" {
-		sourceCtx = globalCtx
+	} else if opTerm.children[0].symbol() == SymVariable && opTerm.children[0].Source() == "global" {
+		sourceCtx = ctx.GetGlobal()
 	} else if childValue, err = opTerm.evalPrefix(ctx); err == nil {
 		if dc, ok := childValue.(*dataCursor); ok {
 			sourceCtx = dc.ctx
@@ -31,9 +35,9 @@ func evalContextValue(ctx ExprContext, opTerm *term) (v any, err error) {
 	}
 
 	if sourceCtx != nil {
-		if formatter, ok := sourceCtx.(DictFormat); ok {
+		if formatter, ok := sourceCtx.(kern.DictFormat); ok {
 			v = formatter.ToDict()
-		} else if formatter, ok := sourceCtx.(Formatter); ok {
+		} else if formatter, ok := sourceCtx.(kern.Formatter); ok {
 			v = formatter.ToString(0)
 		} else {
 			// keys := sourceCtx.EnumVars(func(name string) bool { return name[0] != '_' })
@@ -49,7 +53,7 @@ func evalContextValue(ctx ExprContext, opTerm *term) (v any, err error) {
 			v = d
 		}
 	} else {
-		err = opTerm.errIncompatibleType(childValue)
+		err = opTerm.errIncompatiblePrefixPostfixType(childValue)
 	}
 	return
 }

operator-ctrl.go

@@ -4,6 +4,10 @@
 // operator-ctrl.go
 package expr
 
+import (
+	"git.portale-stac.it/go-pkg/expr/kern"
+)
+
 //-------- export all term
 
 func newExportAllTerm(tk *Token) (inst *term) {
@@ -16,8 +20,8 @@ func newExportAllTerm(tk *Token) (inst *term) {
 	}
 }
 
-func evalExportAll(ctx ExprContext, opTerm *term) (v any, err error) {
-	CtrlEnable(ctx, control_export_all)
+func evalExportAll(ctx kern.ExprContext, opTerm *term) (v any, err error) {
+	CtrlEnable(ctx, kern.ControlExportAll)
 	return
 }
 

operator-default.go

@@ -4,6 +4,10 @@
 // operator-default.go
 package expr
 
+import (
+	"git.portale-stac.it/go-pkg/expr/kern"
+)
+
 //-------- default term
 
 func newDefaultTerm(tk *Token) (inst *term) {
@@ -16,7 +20,7 @@ func newDefaultTerm(tk *Token) (inst *term) {
 	}
 }
 
-func evalDefault(ctx ExprContext, opTerm *term) (v any, err error) {
+func evalDefault(ctx kern.ExprContext, opTerm *term) (v any, err error) {
 	var rightValue any
 
 	if err = opTerm.checkOperands(); err != nil {
@@ -26,13 +30,13 @@ func evalDefault(ctx ExprContext, opTerm *term) (v any, err error) {
 	leftTerm := opTerm.children[0]
 	if leftTerm.tk.Sym != SymVariable {
 		// err = leftTerm.Errorf("left operand of %q must be a variable", self.tk.source)
-		err = ErrLeftOperandMustBeVariable(leftTerm, opTerm)
+		err = kern.ErrLeftOperandMustBeVariable(leftTerm, opTerm)
 		return
 	}
 
-	if leftValue, exists := ctx.GetVar(leftTerm.source()); exists {
+	if leftValue, exists := ctx.GetVar(leftTerm.Source()); exists {
 		v = leftValue
-	} else if rightValue, err = opTerm.children[1].compute(ctx); err == nil {
+	} else if rightValue, err = opTerm.children[1].Compute(ctx); err == nil {
 		v = rightValue
 	}
 	return
@@ -50,7 +54,7 @@ func newAlternateTerm(tk *Token) (inst *term) {
 	}
 }
 
-func evalAlternate(ctx ExprContext, opTerm *term) (v any, err error) {
+func evalAlternate(ctx kern.ExprContext, opTerm *term) (v any, err error) {
 	var rightValue any
 
 	if err = opTerm.checkOperands(); err != nil {
@@ -60,12 +64,12 @@ func evalAlternate(ctx ExprContext, opTerm *term) (v any, err error) {
 	leftTerm := opTerm.children[0]
 	if leftTerm.tk.Sym != SymVariable {
 		// err = leftTerm.Errorf("left operand of %q must be a variable", self.tk.source)
-		err = ErrLeftOperandMustBeVariable(leftTerm, opTerm)
+		err = kern.ErrLeftOperandMustBeVariable(leftTerm, opTerm)
 		return
 	}
 
-	if leftValue, exists := ctx.GetVar(leftTerm.source()); exists && leftValue != nil {
-		if rightValue, err = opTerm.children[1].compute(ctx); err == nil {
+	if leftValue, exists := ctx.GetVar(leftTerm.Source()); exists && leftValue != nil {
+		if rightValue, err = opTerm.children[1].Compute(ctx); err == nil {
 			v = rightValue
 		}
 	} else {
@@ -86,7 +90,7 @@ func newDefaultAssignTerm(tk *Token) (inst *term) {
 	}
 }
 
-func evalAssignDefault(ctx ExprContext, opTerm *term) (v any, err error) {
+func evalAssignDefault(ctx kern.ExprContext, opTerm *term) (v any, err error) {
 	var rightValue any
 
 	if err = opTerm.checkOperands(); err != nil {
@@ -96,21 +100,21 @@ func evalAssignDefault(ctx ExprContext, opTerm *term) (v any, err error) {
 	leftTerm := opTerm.children[0]
 	if leftTerm.tk.Sym != SymVariable {
 		// err = leftTerm.Errorf("left operand of %q must be a variable", self.tk.source)
-		err = ErrLeftOperandMustBeVariable(leftTerm, opTerm)
+		err = kern.ErrLeftOperandMustBeVariable(leftTerm, opTerm)
 		return
 	}
 
-	if leftValue, exists := ctx.GetVar(leftTerm.source()); exists {
+	if leftValue, exists := ctx.GetVar(leftTerm.Source()); exists {
 		v = leftValue
-	} else if rightValue, err = opTerm.children[1].compute(ctx); err == nil {
-		if functor, ok := rightValue.(Functor); ok {
+	} else if rightValue, err = opTerm.children[1].Compute(ctx); err == nil {
+		if functor, ok := rightValue.(kern.Functor); ok {
 			//ctx.RegisterFunc(leftTerm.source(), functor, 0, -1)
-			ctx.RegisterFunc(leftTerm.source(), functor, TypeAny, []ExprFuncParam{
-				NewFuncParamFlag(ParamValue, PfDefault|PfRepeat),
+			ctx.RegisterFunc(leftTerm.Source(), functor, kern.TypeAny, []kern.ExprFuncParam{
+				NewFuncParamFlag(kern.ParamValue, PfDefault|PfRepeat),
 			})
 		} else {
 			v = rightValue
-			ctx.UnsafeSetVar(leftTerm.source(), rightValue)
+			ctx.UnsafeSetVar(leftTerm.Source(), rightValue)
 		}
 	}
 	return

operator-digest.go

@@ -7,6 +7,8 @@ package expr
 import (
 	"fmt"
 	"io"
+
+	"git.portale-stac.it/go-pkg/expr/kern"
 )
 
 //-------- digest term
@@ -21,21 +23,21 @@ func newDigestTerm(tk *Token) (inst *term) {
 	}
 }
 
-func evalDigest(ctx ExprContext, opTerm *term) (v any, err error) {
+func evalDigest(ctx kern.ExprContext, opTerm *term) (v any, err error) {
 	var leftValue, rightValue any
-	var it Iterator
+	var it kern.Iterator
 	var item, lastValue any
 
 	if err = opTerm.checkOperands(); err != nil {
 		return
 	}
 
-	if leftValue, err = opTerm.children[0].compute(ctx); err != nil {
+	if leftValue, err = opTerm.children[0].Compute(ctx); err != nil {
 		return
 	}
 
 	if it, err = NewIterator(leftValue); err != nil {
-		return nil, fmt.Errorf("left operand of DIGEST must be an iterable data-source; got %s", TypeName(leftValue))
+		return nil, fmt.Errorf("left operand of DIGEST must be an iterable data-source; got %s", kern.TypeName(leftValue))
 	}
 
 	lastValue = nil
@@ -43,7 +45,7 @@ func evalDigest(ctx ExprContext, opTerm *term) (v any, err error) {
 		ctx.SetVar("_", item)
 		ctx.SetVar("_index", it.Index())
 		ctx.SetVar("_count", it.Count())
-		if rightValue, err = opTerm.children[1].compute(ctx); err == nil {
+		if rightValue, err = opTerm.children[1].Compute(ctx); err == nil {
 			if rightValue == nil {
 				break
 			} else {

operator-dot.go

@@ -4,6 +4,10 @@
 // operator-dot.go
 package expr
 
+import (
+	"git.portale-stac.it/go-pkg/expr/kern"
+)
+
 // -------- dot term
 func newDotTerm(tk *Token) (inst *term) {
 	return &term{
@@ -15,22 +19,22 @@ func newDotTerm(tk *Token) (inst *term) {
 	}
 }
 
-func evalDot(ctx ExprContext, opTerm *term) (v any, err error) {
+func evalDot(ctx kern.ExprContext, opTerm *term) (v any, err error) {
 	var leftValue, rightValue any
 
 	if err = opTerm.checkOperands(); err != nil {
 		return
 	}
-	if leftValue, err = opTerm.children[0].compute(ctx); err != nil {
+	if leftValue, err = opTerm.children[0].Compute(ctx); err != nil {
 		return
 	}
 
 	indexTerm := opTerm.children[1]
 
 	switch unboxedValue := leftValue.(type) {
-	case ExtIterator:
+	case kern.ExtIterator:
 		if indexTerm.symbol() == SymVariable /*|| indexTerm.symbol() == SymString */ {
-			opName := indexTerm.source()
+			opName := indexTerm.Source()
 			if unboxedValue.HasOperation(opName) {
 				v, err = unboxedValue.CallOperation(opName, map[string]any{})
 			} else {
@@ -40,8 +44,19 @@ func evalDot(ctx ExprContext, opTerm *term) (v any, err error) {
 		} else {
 			err = indexTerm.tk.ErrorExpectedGot("identifier")
 		}
+	case *kern.DictType:
+		s := opTerm.children[1].symbol()
+		if s == SymVariable || s == SymString {
+			src := opTerm.children[1].Source()
+			if len(src) > 1 && src[0] == '"' && src[len(src)-1] == '"' {
+				src = src[1 : len(src)-1]
+			}
+			v, err = unboxedValue.GetItem(src)
+		} else if rightValue, err = opTerm.children[1].Compute(ctx); err == nil {
+			v, err = unboxedValue.GetItem(rightValue)
+		}
 	default:
-		if rightValue, err = opTerm.children[1].compute(ctx); err == nil {
+		if rightValue, err = opTerm.children[1].Compute(ctx); err == nil {
 			err = opTerm.errIncompatibleTypes(leftValue, rightValue)
 		}
 	}

operator-fact.go

@@ -4,7 +4,11 @@
 // operator-fact.go
 package expr
 
-import "fmt"
+import (
+	"fmt"
+
+	"git.portale-stac.it/go-pkg/expr/kern"
+)
 
 //-------- fact term
 
@@ -18,14 +22,14 @@ func newFactTerm(tk *Token) (inst *term) {
 	}
 }
 
-func evalFact(ctx ExprContext, opTerm *term) (v any, err error) {
+func evalFact(ctx kern.ExprContext, opTerm *term) (v any, err error) {
 	var leftValue any
 
 	if leftValue, err = opTerm.evalPrefix(ctx); err != nil {
 		return
 	}
 
-	if IsInteger(leftValue) {
+	if kern.IsInteger(leftValue) {
 		if i, _ := leftValue.(int64); i >= 0 {
 			f := int64(1)
 			for k := int64(1); k <= i; k++ {
@@ -36,7 +40,7 @@ func evalFact(ctx ExprContext, opTerm *term) (v any, err error) {
 			err = fmt.Errorf("factorial of a negative integer (%d) is not allowed", i)
 		}
 	} else {
-		err = opTerm.errIncompatibleType(leftValue)
+		err = opTerm.errIncompatiblePrefixPostfixType(leftValue)
 	}
 	return
 }

operator-filter.go

@@ -7,6 +7,8 @@ package expr
 import (
 	"fmt"
 	"io"
+
+	"git.portale-stac.it/go-pkg/expr/kern"
 )
 
 //-------- map term
@@ -21,32 +23,32 @@ func newFilterTerm(tk *Token) (inst *term) {
 	}
 }
 
-func evalFilter(ctx ExprContext, opTerm *term) (v any, err error) {
+func evalFilter(ctx kern.ExprContext, opTerm *term) (v any, err error) {
 	var leftValue, rightValue any
-	var it Iterator
+	var it kern.Iterator
 	var item any
 
 	if err = opTerm.checkOperands(); err != nil {
 		return
 	}
 
-	if leftValue, err = opTerm.children[0].compute(ctx); err != nil {
+	if leftValue, err = opTerm.children[0].Compute(ctx); err != nil {
 		return
 	}
 
 	if it, err = NewIterator(leftValue); err != nil {
-		return nil, fmt.Errorf("left operand of FILTER must be an iterable data-source; got %s", TypeName(leftValue))
+		return nil, fmt.Errorf("left operand of FILTER must be an iterable data-source; got %s", kern.TypeName(leftValue))
 	}
 
-	values := newListA()
+	values := kern.NewListA()
 	for item, err = it.Next(); err == nil; item, err = it.Next() {
 		ctx.SetVar("_", item)
 		ctx.SetVar("_index", it.Index())
 		ctx.SetVar("_count", it.Count())
-		if rightValue, err = opTerm.children[1].compute(ctx); err == nil {
-			if success, valid := ToBool(rightValue); valid {
+		if rightValue, err = opTerm.children[1].Compute(ctx); err == nil {
+			if success, valid := kern.ToBool(rightValue); valid {
 				if success {
-					values.appendItem(item)
+					values.AppendItem(item)
 				}
 			} else {
 				err = fmt.Errorf("filter expression must return a boolean or a castable to boolean, got %v [%T]", rightValue, rightValue)

operator-fraction.go

@@ -8,6 +8,8 @@ package expr
 
 import (
 	"fmt"
+
+	"git.portale-stac.it/go-pkg/expr/kern"
 )
 
 // -------- fraction term
@@ -23,7 +25,7 @@ func newFractionTerm(tk *Token) *term {
 }
 
 // -------- eval func
-func evalFraction(ctx ExprContext, opTerm *term) (v any, err error) {
+func evalFraction(ctx kern.ExprContext, opTerm *term) (v any, err error) {
 	var numValue, denValue any
 	var num, den int64
 	var ok bool
@@ -49,16 +51,19 @@ func evalFraction(ctx ExprContext, opTerm *term) (v any, err error) {
 		num = -num
 	}
 	if num != 0 {
-		g := gcd(num, den)
-		num = num / g
-		den = den / g
+		if g := kern.Gcd(num, den); g != 1 {
+			num = num / g
+			den = den / g
+		}
 		if den == 1 {
 			v = num
 		} else {
-			v = &FractionType{num, den}
+			// v = &expr.FractionType{num, den}
+			v = kern.NewFraction(num, den)
 		}
 	} else {
-		v = &FractionType{0, den}
+		// v = &FractionType{0, den}
+		v = kern.NewFraction(0, den)
 	}
 	return
 }

operator-in.go

@@ -4,6 +4,10 @@
 // operator-in.go
 package expr
 
+import (
+	"git.portale-stac.it/go-pkg/expr/kern"
+)
+
 //-------- in term
 
 func newInTerm(tk *Token) (inst *term) {
@@ -21,19 +25,19 @@ func newInTerm(tk *Token) (inst *term) {
 // 	return
 // }
 
-func evalIn(ctx ExprContext, opTerm *term) (v any, err error) {
+func evalIn(ctx kern.ExprContext, opTerm *term) (v any, err error) {
 	var leftValue, rightValue any
 
 	if leftValue, rightValue, err = opTerm.evalInfix(ctx); err != nil {
 		return
 	}
 
-	if IsList(rightValue) {
-		list, _ := rightValue.(*ListType)
-		v = list.indexDeepSameCmp(leftValue) >= 0
-	} else if IsDict(rightValue) {
-		dict, _ := rightValue.(*DictType)
-		v = dict.hasKey(leftValue)
+	if kern.IsList(rightValue) {
+		list, _ := rightValue.(*kern.ListType)
+		v = list.IndexDeepSameCmp(leftValue) >= 0
+	} else if kern.IsDict(rightValue) {
+		dict, _ := rightValue.(*kern.DictType)
+		v = dict.HasKey(leftValue)
 	} else {
 		err = opTerm.errIncompatibleTypes(leftValue, rightValue)
 	}

operator-include.go

@@ -4,6 +4,10 @@
 // operator-include.go
 package expr
 
+import (
+	"git.portale-stac.it/go-pkg/expr/kern"
+)
+
 //-------- include term
 
 func newIncludeTerm(tk *Token) (inst *term) {
@@ -16,7 +20,7 @@ func newIncludeTerm(tk *Token) (inst *term) {
 	}
 }
 
-func evalInclude(ctx ExprContext, opTerm *term) (v any, err error) {
+func evalInclude(ctx kern.ExprContext, opTerm *term) (v any, err error) {
 	var childValue any
 
 	if childValue, err = opTerm.evalPrefix(ctx); err != nil {
@@ -24,8 +28,8 @@ func evalInclude(ctx ExprContext, opTerm *term) (v any, err error) {
 	}
 
 	count := 0
-	if IsList(childValue) {
-		list, _ := childValue.(*ListType)
+	if kern.IsList(childValue) {
+		list, _ := childValue.(*kern.ListType)
 		for i, filePathSpec := range *list {
 			if filePath, ok := filePathSpec.(string); ok {
 				if v, err = EvalFile(ctx, filePath); err == nil {
@@ -39,13 +43,13 @@ func evalInclude(ctx ExprContext, opTerm *term) (v any, err error) {
 				break
 			}
 		}
-	} else if IsString(childValue) {
+	} else if kern.IsString(childValue) {
 		filePath, _ := childValue.(string)
 		if v, err = EvalFile(ctx, filePath); err == nil {
 			count++
 		}
 	} else {
-		err = opTerm.errIncompatibleType(childValue)
+		err = opTerm.errIncompatiblePrefixPostfixType(childValue)
 	}
 	if err != nil {
 		//v = count

operator-index.go

@@ -4,6 +4,10 @@
 // operator-index.go
 package expr
 
+import (
+	"git.portale-stac.it/go-pkg/expr/kern"
+)
+
 // -------- index term
 func newIndexTerm(tk *Token) (inst *term) {
 	return &term{
@@ -15,15 +19,15 @@ func newIndexTerm(tk *Token) (inst *term) {
 	}
 }
 
-func verifyKey(indexList *ListType) (index any, err error) {
+func verifyKey(indexList *kern.ListType) (index any, err error) {
 	index = (*indexList)[0]
 	return
 }
 
-func verifyIndex(indexTerm *term, indexList *ListType, maxValue int) (index int, err error) {
+func verifyIndex(indexTerm *term, indexList *kern.ListType, maxValue int) (index int, err error) {
 	var v int
 
-	if v, err = ToGoInt((*indexList)[0], "index expression"); err == nil {
+	if v, err = kern.ToGoInt((*indexList)[0], "index expression"); err == nil {
 		if v < 0 && v >= -maxValue {
 			v = maxValue + v
 		}
@@ -36,11 +40,11 @@ func verifyIndex(indexTerm *term, indexList *ListType, maxValue int) (index int,
 	return
 }
 
-func verifyRange(indexTerm *term, indexList *ListType, maxValue int) (startIndex, endIndex int, err error) {
+func verifyRange(indexTerm *term, indexList *kern.ListType, maxValue int) (startIndex, endIndex int, err error) {
 	v, _ := ((*indexList)[0]).(*intPair)
 	startIndex = v.a
 	endIndex = v.b
-	if endIndex == ConstLastIndex {
+	if endIndex == kern.ConstLastIndex {
 		endIndex = maxValue
 	}
 	if startIndex < 0 && startIndex >= -maxValue {
@@ -59,9 +63,9 @@ func verifyRange(indexTerm *term, indexList *ListType, maxValue int) (startIndex
 	return
 }
 
-func evalIndex(ctx ExprContext, opTerm *term) (v any, err error) {
+func evalIndex(ctx kern.ExprContext, opTerm *term) (v any, err error) {
 	var leftValue, rightValue any
-	var indexList *ListType
+	var indexList *kern.ListType
 	var ok bool
 
 	if leftValue, rightValue, err = opTerm.evalInfix(ctx); err != nil {
@@ -69,7 +73,7 @@ func evalIndex(ctx ExprContext, opTerm *term) (v any, err error) {
 	}
 
 	indexTerm := opTerm.children[1]
-	if indexList, ok = rightValue.(*ListType); !ok {
+	if indexList, ok = rightValue.(*kern.ListType); !ok {
 		err = opTerm.Errorf("invalid index expression")
 		return
 	} else if len(*indexList) != 1 {
@@ -77,9 +81,9 @@ func evalIndex(ctx ExprContext, opTerm *term) (v any, err error) {
 		return
 	}
 
-	if IsInteger((*indexList)[0]) {
+	if kern.IsInteger((*indexList)[0]) {
 		switch unboxedValue := leftValue.(type) {
-		case *ListType:
+		case *kern.ListType:
 			var index int
 			if index, err = verifyIndex(indexTerm, indexList, len(*unboxedValue)); err == nil {
 				v = (*unboxedValue)[index]
@@ -89,17 +93,17 @@ func evalIndex(ctx ExprContext, opTerm *term) (v any, err error) {
 			if index, err = verifyIndex(indexTerm, indexList, len(unboxedValue)); err == nil {
 				v = string(unboxedValue[index])
 			}
-		case *DictType:
+		case *kern.DictType:
 			v, err = getDictItem(unboxedValue, indexTerm, indexList, rightValue)
 		default:
 			err = opTerm.errIncompatibleTypes(leftValue, rightValue)
 		}
 	} else if isIntPair((*indexList)[0]) {
 		switch unboxedValue := leftValue.(type) {
-		case *ListType:
+		case *kern.ListType:
 			var start, end int
 			if start, end, err = verifyRange(indexTerm, indexList, len(*unboxedValue)); err == nil {
-				sublist := ListType((*unboxedValue)[start:end])
+				sublist := kern.ListType((*unboxedValue)[start:end])
 				v = &sublist
 			}
 		case string:
@@ -110,8 +114,8 @@ func evalIndex(ctx ExprContext, opTerm *term) (v any, err error) {
 		default:
 			err = opTerm.errIncompatibleTypes(leftValue, rightValue)
 		}
-	} else if IsDict(leftValue) {
-		d := leftValue.(*DictType)
+	} else if kern.IsDict(leftValue) {
+		d := leftValue.(*kern.DictType)
 		v, err = getDictItem(d, indexTerm, indexList, rightValue)
 	} else {
 		rightChild := opTerm.children[1]
@@ -120,7 +124,7 @@ func evalIndex(ctx ExprContext, opTerm *term) (v any, err error) {
 	return
 }
 
-func getDictItem(d *DictType, indexTerm *term, indexList *ListType, rightValue any) (v any, err error) {
+func getDictItem(d *kern.DictType, indexTerm *term, indexList *kern.ListType, rightValue any) (v any, err error) {
 	var ok bool
 	var indexValue any
 

operator-insert.go

@@ -4,6 +4,10 @@
 // operator-insert.go
 package expr
 
+import (
+	"git.portale-stac.it/go-pkg/expr/kern"
+)
+
 //-------- prepend term
 
 func newPrependTerm(tk *Token) (inst *term) {
@@ -26,19 +30,19 @@ func newAppendTerm(tk *Token) (inst *term) {
 	}
 }
 
-func evalPrepend(ctx ExprContext, opTerm *term) (v any, err error) {
+func evalPrepend(ctx kern.ExprContext, opTerm *term) (v any, err error) {
 	var leftValue, rightValue any
 
 	if leftValue, rightValue, err = opTerm.evalInfix(ctx); err != nil {
 		return
 	}
 
-	if IsList(rightValue) {
-		list, _ := rightValue.(*ListType)
-		newList := append(ListType{leftValue}, *list...)
+	if kern.IsList(rightValue) {
+		list, _ := rightValue.(*kern.ListType)
+		newList := append(kern.ListType{leftValue}, *list...)
 		v = &newList
 		if opTerm.children[1].symbol() == SymVariable {
-			ctx.UnsafeSetVar(opTerm.children[1].source(), v)
+			ctx.UnsafeSetVar(opTerm.children[1].Source(), v)
 		}
 	} else {
 		err = opTerm.errIncompatibleTypes(leftValue, rightValue)
@@ -46,19 +50,19 @@ func evalPrepend(ctx ExprContext, opTerm *term) (v any, err error) {
 	return
 }
 
-func evalAppend(ctx ExprContext, opTerm *term) (v any, err error) {
+func evalAppend(ctx kern.ExprContext, opTerm *term) (v any, err error) {
 	var leftValue, rightValue any
 
 	if leftValue, rightValue, err = opTerm.evalInfix(ctx); err != nil {
 		return
 	}
 
-	if IsList(leftValue) {
-		list, _ := leftValue.(*ListType)
+	if kern.IsList(leftValue) {
+		list, _ := leftValue.(*kern.ListType)
 		newList := append(*list, rightValue)
 		v = &newList
 		if opTerm.children[0].symbol() == SymVariable {
-			ctx.UnsafeSetVar(opTerm.children[0].source(), v)
+			ctx.UnsafeSetVar(opTerm.children[0].Source(), v)
 		}
 	} else {
 		err = opTerm.errIncompatibleTypes(leftValue, rightValue)

operator-iter-value.go

@@ -4,6 +4,10 @@
 // operator-iter-value.go
 package expr
 
+import (
+	"git.portale-stac.it/go-pkg/expr/kern"
+)
+
 //-------- iter value term
 
 func newIterValueTerm(tk *Token) (inst *term) {
@@ -16,17 +20,17 @@ func newIterValueTerm(tk *Token) (inst *term) {
 	}
 }
 
-func evalIterValue(ctx ExprContext, opTerm *term) (v any, err error) {
+func evalIterValue(ctx kern.ExprContext, opTerm *term) (v any, err error) {
 	var childValue any
 
 	if childValue, err = opTerm.evalPrefix(ctx); err != nil {
 		return
 	}
 
-	if it, ok := childValue.(Iterator); ok {
+	if it, ok := childValue.(kern.Iterator); ok {
 		v, err = it.Current()
 	} else {
-		err = opTerm.errIncompatibleType(childValue)
+		err = opTerm.errIncompatiblePrefixPostfixType(childValue)
 	}
 	return
 }

operator-join.go

@@ -7,6 +7,8 @@ package expr
 import (
 	"fmt"
 	"io"
+
+	"git.portale-stac.it/go-pkg/expr/kern"
 )
 
 //-------- join term
@@ -21,35 +23,35 @@ func newJoinTerm(tk *Token) (inst *term) {
 	}
 }
 
-func evalJoin(ctx ExprContext, opTerm *term) (v any, err error) {
+func evalJoin(ctx kern.ExprContext, opTerm *term) (v any, err error) {
 	var leftValue, rightValue any
-	var itLeft, itRight Iterator
+	var itLeft, itRight kern.Iterator
 	var item any
 
 	if err = opTerm.checkOperands(); err != nil {
 		return
 	}
 
-	if leftValue, err = opTerm.children[0].compute(ctx); err != nil {
+	if leftValue, err = opTerm.children[0].Compute(ctx); err != nil {
 		return
 	}
 
-	if rightValue, err = opTerm.children[1].compute(ctx); err != nil {
+	if rightValue, err = opTerm.children[1].Compute(ctx); err != nil {
 		return
 	}
 
 	if itLeft, err = NewIterator(leftValue); err != nil {
-		return nil, fmt.Errorf("left operand of JOIN must be an iterable data-source; got %s", TypeName(leftValue))
+		return nil, fmt.Errorf("left operand of JOIN must be an iterable data-source; got %s", kern.TypeName(leftValue))
 	}
 
 	if itRight, err = NewIterator(rightValue); err != nil {
-		return nil, fmt.Errorf("right operand of JOIN must be an iterable data-source; got %s", TypeName(rightValue))
+		return nil, fmt.Errorf("right operand of JOIN must be an iterable data-source; got %s", kern.TypeName(rightValue))
 	}
 
-	values := newListA()
-	for _, it := range []Iterator{itLeft, itRight} {
+	values := kern.NewListA()
+	for _, it := range []kern.Iterator{itLeft, itRight} {
 		for item, err = it.Next(); err == nil; item, err = it.Next() {
-			values.appendItem(item)
+			values.AppendItem(item)
 		}
 	}
 	if err == io.EOF {

operator-length.go

@@ -4,6 +4,10 @@
 // operator-length.go
 package expr
 
+import (
+	"git.portale-stac.it/go-pkg/expr/kern"
+)
+
 //-------- length term
 
 func newLengthTerm(tk *Token) (inst *term) {
@@ -16,23 +20,23 @@ func newLengthTerm(tk *Token) (inst *term) {
 	}
 }
 
-func evalLength(ctx ExprContext, opTerm *term) (v any, err error) {
+func evalLength(ctx kern.ExprContext, opTerm *term) (v any, err error) {
 	var childValue any
 
 	if childValue, err = opTerm.evalPrefix(ctx); err != nil {
 		return
 	}
 
-	if IsList(childValue) {
-		ls, _ := childValue.(*ListType)
+	if kern.IsList(childValue) {
+		ls, _ := childValue.(*kern.ListType)
 		v = int64(len(*ls))
-	} else if IsString(childValue) {
+	} else if kern.IsString(childValue) {
 		s, _ := childValue.(string)
 		v = int64(len(s))
-	} else if IsDict(childValue) {
-		m, _ := childValue.(*DictType)
+	} else if kern.IsDict(childValue) {
+		m, _ := childValue.(*kern.DictType)
 		v = int64(len(*m))
-	} else if it, ok := childValue.(Iterator); ok {
+	} else if it, ok := childValue.(kern.Iterator); ok {
 		v = int64(it.Count())
 		// if extIt, ok := childValue.(ExtIterator); ok && extIt.HasOperation(CountName) {
 		// 	count, _ := extIt.CallOperation(CountName, nil)
@@ -41,7 +45,7 @@ func evalLength(ctx ExprContext, opTerm *term) (v any, err error) {
 		// 	v = int64(it.Index() + 1)
 		// }
 	} else {
-		err = opTerm.errIncompatibleType(childValue)
+		err = opTerm.errIncompatiblePrefixPostfixType(childValue)
 	}
 	return
 }

operator-map.go

@@ -7,6 +7,8 @@ package expr
 import (
 	"fmt"
 	"io"
+
+	"git.portale-stac.it/go-pkg/expr/kern"
 )
 
 //-------- map term
@@ -21,30 +23,30 @@ func newMapTerm(tk *Token) (inst *term) {
 	}
 }
 
-func evalMap(ctx ExprContext, opTerm *term) (v any, err error) {
+func evalMap(ctx kern.ExprContext, opTerm *term) (v any, err error) {
 	var leftValue, rightValue any
-	var it Iterator
+	var it kern.Iterator
 	var item any
 
 	if err = opTerm.checkOperands(); err != nil {
 		return
 	}
 
-	if leftValue, err = opTerm.children[0].compute(ctx); err != nil {
+	if leftValue, err = opTerm.children[0].Compute(ctx); err != nil {
 		return
 	}
 
 	if it, err = NewIterator(leftValue); err != nil {
-		return nil, fmt.Errorf("left operand of MAP must be an iterable data-source; got %s", TypeName(leftValue))
+		return nil, fmt.Errorf("left operand of MAP must be an iterable data-source; got %s", kern.TypeName(leftValue))
 	}
 
-	values := newListA()
+	values := kern.NewListA()
 	for item, err = it.Next(); err == nil; item, err = it.Next() {
 		ctx.SetVar("_", item)
 		ctx.SetVar("_index", it.Index())
 		ctx.SetVar("_count", it.Count())
-		if rightValue, err = opTerm.children[1].compute(ctx); err == nil {
-			values.appendItem(rightValue)
+		if rightValue, err = opTerm.children[1].Compute(ctx); err == nil {
+			values.AppendItem(rightValue)
 		}
 		ctx.DeleteVar("_count")
 		ctx.DeleteVar("_index")

operator-plugin.go

@@ -4,6 +4,10 @@
 // operator-plugin.go
 package expr
 
+import (
+	"git.portale-stac.it/go-pkg/expr/kern"
+)
+
 //-------- plugin term
 
 func newPluginTerm(tk *Token) (inst *term) {
@@ -16,7 +20,7 @@ func newPluginTerm(tk *Token) (inst *term) {
 	}
 }
 
-func evalPlugin(ctx ExprContext, opTerm *term) (v any, err error) {
+func evalPlugin(ctx kern.ExprContext, opTerm *term) (v any, err error) {
 	var childValue any
 	var count int
 
@@ -24,7 +28,7 @@ func evalPlugin(ctx ExprContext, opTerm *term) (v any, err error) {
 		return
 	}
 
-	if count, err = importPluginFromSearchPath(childValue); err == nil {
+	if count, err = importPluginFromSearchPath(ctx, childValue); err == nil {
 		v = int64(count)
 	}
 	return

operator-post-inc-dec.go

@@ -4,6 +4,10 @@
 // operator-post-inc-dec.go
 package expr
 
+import (
+	"git.portale-stac.it/go-pkg/expr/kern"
+)
+
 // -------- post increment term
 
 func newPostIncTerm(tk *Token) *term {
@@ -17,40 +21,40 @@ func newPostIncTerm(tk *Token) *term {
 	}
 }
 
-func evalPostInc(ctx ExprContext, opTerm *term) (v any, err error) {
+func evalPostInc(ctx kern.ExprContext, opTerm *term) (v any, err error) {
 	var childValue any
 	if childValue, err = opTerm.evalPrefix(ctx); err != nil {
 		return
 	}
 
-	if it, ok := childValue.(Iterator); ok {
+	if it, ok := childValue.(kern.Iterator); ok {
 		var namePrefix string
 		v, err = it.Next()
 
 		if opTerm.children[0].symbol() == SymVariable {
-			namePrefix = opTerm.children[0].source()
+			namePrefix = opTerm.children[0].Source()
 		}
 		ctx.UnsafeSetVar(namePrefix+"_index", it.Index())
 		if c, err1 := it.Current(); err1 == nil {
 			ctx.UnsafeSetVar(namePrefix+"_current", c)
 		}
 
-		if it.HasOperation(KeyName) {
-			if k, err1 := it.CallOperation(KeyName, nil); err1 == nil {
+		if it.HasOperation(kern.KeyName) {
+			if k, err1 := it.CallOperation(kern.KeyName, nil); err1 == nil {
 				ctx.UnsafeSetVar(namePrefix+"_key", k)
 			}
 		}
-		if it.HasOperation(ValueName) {
-			if v1, err1 := it.CallOperation(ValueName, nil); err1 == nil {
+		if it.HasOperation(kern.ValueName) {
+			if v1, err1 := it.CallOperation(kern.ValueName, nil); err1 == nil {
 				ctx.UnsafeSetVar(namePrefix+"_value", v1)
 			}
 		}
-	} else if IsInteger(childValue) && opTerm.children[0].symbol() == SymVariable {
+	} else if kern.IsInteger(childValue) && opTerm.children[0].symbol() == SymVariable {
 		v = childValue
 		i, _ := childValue.(int64)
-		ctx.SetVar(opTerm.children[0].source(), i+1)
+		ctx.SetVar(opTerm.children[0].Source(), i+1)
 	} else {
-		err = opTerm.errIncompatibleType(childValue)
+		err = opTerm.errIncompatiblePrefixPostfixType(childValue)
 	}
 	return
 }
@@ -68,7 +72,7 @@ func newPostDecTerm(tk *Token) *term {
 	}
 }
 
-func evalPostDec(ctx ExprContext, opTerm *term) (v any, err error) {
+func evalPostDec(ctx kern.ExprContext, opTerm *term) (v any, err error) {
 	var childValue any
 	if childValue, err = opTerm.evalPrefix(ctx); err != nil {
 		return
@@ -76,12 +80,12 @@ func evalPostDec(ctx ExprContext, opTerm *term) (v any, err error) {
 
 	/* if it, ok := childValue.(Iterator); ok {
 		v, err = it.Next()
-	} else  */if IsInteger(childValue) && opTerm.children[0].symbol() == SymVariable {
+	} else  */if kern.IsInteger(childValue) && opTerm.children[0].symbol() == SymVariable {
 		v = childValue
 		i, _ := childValue.(int64)
-		ctx.SetVar(opTerm.children[0].source(), i-1)
+		ctx.SetVar(opTerm.children[0].Source(), i-1)
 	} else {
-		err = opTerm.errIncompatibleType(childValue)
+		err = opTerm.errIncompatiblePrefixPostfixType(childValue)
 	}
 	return
 }

operator-pre-inc-dec.go

@@ -4,6 +4,10 @@
 // operator-pre-inc-dec.go
 package expr
 
+import (
+	"git.portale-stac.it/go-pkg/expr/kern"
+)
+
 // -------- pre increment term
 
 func newPreIncTerm(tk *Token) *term {
@@ -17,18 +21,18 @@ func newPreIncTerm(tk *Token) *term {
 	}
 }
 
-func evalPreInc(ctx ExprContext, opTerm *term) (v any, err error) {
+func evalPreInc(ctx kern.ExprContext, opTerm *term) (v any, err error) {
 	var childValue any
 	if childValue, err = opTerm.evalPrefix(ctx); err != nil {
 		return
 	}
 
-	if IsInteger(childValue) && opTerm.children[0].symbol() == SymVariable {
+	if kern.IsInteger(childValue) && opTerm.children[0].symbol() == SymVariable {
 		i := childValue.(int64) + 1
-		ctx.SetVar(opTerm.children[0].source(), i)
+		ctx.SetVar(opTerm.children[0].Source(), i)
 		v = i
 	} else {
-		err = opTerm.errIncompatibleType(childValue)
+		err = opTerm.errIncompatiblePrefixPostfixType(childValue)
 	}
 	return
 }
@@ -46,18 +50,18 @@ func newPreDecTerm(tk *Token) *term {
 	}
 }
 
-func evalPreDec(ctx ExprContext, opTerm *term) (v any, err error) {
+func evalPreDec(ctx kern.ExprContext, opTerm *term) (v any, err error) {
 	var childValue any
 	if childValue, err = opTerm.evalPrefix(ctx); err != nil {
 		return
 	}
 
-	if IsInteger(childValue) && opTerm.children[0].symbol() == SymVariable {
+	if kern.IsInteger(childValue) && opTerm.children[0].symbol() == SymVariable {
 		i := childValue.(int64) - 1
-		ctx.SetVar(opTerm.children[0].source(), i)
+		ctx.SetVar(opTerm.children[0].Source(), i)
 		v = i
 	} else {
-		err = opTerm.errIncompatibleType(childValue)
+		err = opTerm.errIncompatiblePrefixPostfixType(childValue)
 	}
 	return
 }

operator-prod.go

@@ -6,6 +6,8 @@ package expr
 
 import (
 	"strings"
+
+	"git.portale-stac.it/go-pkg/expr/kern"
 )
 
 //-------- multiply term
@@ -21,15 +23,15 @@ func newMultiplyTerm(tk *Token) (inst *term) {
 }
 
 func mulValues(opTerm *term, leftValue, rightValue any) (v any, err error) {
-	if IsString(leftValue) && IsInteger(rightValue) {
+	if kern.IsString(leftValue) && kern.IsInteger(rightValue) {
 		s, _ := leftValue.(string)
 		n, _ := rightValue.(int64)
 		v = strings.Repeat(s, int(n))
-	} else if isNumOrFract(leftValue) && isNumOrFract(rightValue) {
-		if IsFloat(leftValue) || IsFloat(rightValue) {
-			v = numAsFloat(leftValue) * numAsFloat(rightValue)
-		} else if isFraction(leftValue) || isFraction(rightValue) {
-			v, err = mulAnyFract(leftValue, rightValue)
+	} else if kern.IsNumOrFract(leftValue) && kern.IsNumOrFract(rightValue) {
+		if kern.IsFloat(leftValue) || kern.IsFloat(rightValue) {
+			v = kern.NumAsFloat(leftValue) * kern.NumAsFloat(rightValue)
+		} else if kern.IsFraction(leftValue) || kern.IsFraction(rightValue) {
+			v, err = kern.MulAnyFract(leftValue, rightValue)
 		} else {
 			leftInt, _ := leftValue.(int64)
 			rightInt, _ := rightValue.(int64)
@@ -41,7 +43,7 @@ func mulValues(opTerm *term, leftValue, rightValue any) (v any, err error) {
 	return
 }
 
-func evalMultiply(ctx ExprContext, prodTerm *term) (v any, err error) {
+func evalMultiply(ctx kern.ExprContext, prodTerm *term) (v any, err error) {
 	var leftValue, rightValue any
 
 	if leftValue, rightValue, err = prodTerm.evalInfix(ctx); err != nil {
@@ -64,16 +66,16 @@ func newDivideTerm(tk *Token) (inst *term) {
 }
 
 func divValues(opTerm *term, leftValue, rightValue any) (v any, err error) {
-	if isNumOrFract(leftValue) && isNumOrFract(rightValue) {
-		if IsFloat(leftValue) || IsFloat(rightValue) {
-			d := numAsFloat(rightValue)
+	if kern.IsNumOrFract(leftValue) && kern.IsNumOrFract(rightValue) {
+		if kern.IsFloat(leftValue) || kern.IsFloat(rightValue) {
+			d := kern.NumAsFloat(rightValue)
 			if d == 0.0 {
 				err = opTerm.errDivisionByZero()
 			} else {
-				v = numAsFloat(leftValue) / d
+				v = kern.NumAsFloat(leftValue) / d
 			}
-		} else if isFraction(leftValue) || isFraction(rightValue) {
-			v, err = divAnyFract(leftValue, rightValue)
+		} else if kern.IsFraction(leftValue) || kern.IsFraction(rightValue) {
+			v, err = kern.DivAnyFract(leftValue, rightValue)
 		} else {
 			leftInt, _ := leftValue.(int64)
 			if rightInt, _ := rightValue.(int64); rightInt == 0 {
@@ -82,11 +84,11 @@ func divValues(opTerm *term, leftValue, rightValue any) (v any, err error) {
 				v = leftInt / rightInt
 			}
 		}
-	} else if IsString(leftValue) && IsString(rightValue) {
+	} else if kern.IsString(leftValue) && kern.IsString(rightValue) {
 		source := leftValue.(string)
 		sep := rightValue.(string)
-		v = ListFromStrings(strings.Split(source, sep))
-	} else if IsString(leftValue) && IsInteger(rightValue) {
+		v = kern.ListFromStrings(strings.Split(source, sep))
+	} else if kern.IsString(leftValue) && kern.IsInteger(rightValue) {
 		source := leftValue.(string)
 		partSize := int(rightValue.(int64))
 		if partSize == 0 {
@@ -105,7 +107,7 @@ func divValues(opTerm *term, leftValue, rightValue any) (v any, err error) {
 			if remainder > 0 {
 				parts = append(parts, source[len(source)-remainder:])
 			}
-			v = newList(parts)
+			v = kern.NewList(parts)
 		}
 	} else {
 		err = opTerm.errIncompatibleTypes(leftValue, rightValue)
@@ -113,7 +115,7 @@ func divValues(opTerm *term, leftValue, rightValue any) (v any, err error) {
 	return
 }
 
-func evalDivide(ctx ExprContext, opTerm *term) (v any, err error) {
+func evalDivide(ctx kern.ExprContext, opTerm *term) (v any, err error) {
 	var leftValue, rightValue any
 
 	if leftValue, rightValue, err = opTerm.evalInfix(ctx); err != nil {
@@ -135,19 +137,19 @@ func newDivideAsFloatTerm(tk *Token) (inst *term) {
 	}
 }
 
-func evalDivideAsFloat(ctx ExprContext, floatDivTerm *term) (v any, err error) {
+func evalDivideAsFloat(ctx kern.ExprContext, floatDivTerm *term) (v any, err error) {
 	var leftValue, rightValue any
 
 	if leftValue, rightValue, err = floatDivTerm.evalInfix(ctx); err != nil {
 		return
 	}
 
-	if isNumOrFract(leftValue) && isNumOrFract(rightValue) {
-		d := numAsFloat(rightValue)
+	if kern.IsNumOrFract(leftValue) && kern.IsNumOrFract(rightValue) {
+		d := kern.NumAsFloat(rightValue)
 		if d == 0.0 {
 			err = floatDivTerm.errDivisionByZero()
 		} else {
-			v = numAsFloat(leftValue) / d
+			v = kern.NumAsFloat(leftValue) / d
 		}
 	} else {
 		err = floatDivTerm.errIncompatibleTypes(leftValue, rightValue)
@@ -167,7 +169,7 @@ func newRemainderTerm(tk *Token) (inst *term) {
 	}
 }
 func remainderValues(opTerm *term, leftValue, rightValue any) (v any, err error) {
-	if IsInteger(leftValue) && IsInteger(rightValue) {
+	if kern.IsInteger(leftValue) && kern.IsInteger(rightValue) {
 		rightInt, _ := rightValue.(int64)
 		if rightInt == 0 {
 			err = opTerm.errDivisionByZero()
@@ -181,7 +183,7 @@ func remainderValues(opTerm *term, leftValue, rightValue any) (v any, err error)
 	return
 }
 
-func evalRemainder(ctx ExprContext, remainderTerm *term) (v any, err error) {
+func evalRemainder(ctx kern.ExprContext, remainderTerm *term) (v any, err error) {
 	var leftValue, rightValue any
 
 	if leftValue, rightValue, err = remainderTerm.evalInfix(ctx); err != nil {

operator-range.go

@@ -4,7 +4,11 @@
 // operator-range.go
 package expr
 
-import "fmt"
+import (
+	"fmt"
+
+	"git.portale-stac.it/go-pkg/expr/kern"
+)
 
 // -------- range term
 type intPair struct {
@@ -12,10 +16,10 @@ type intPair struct {
 }
 
 func (p *intPair) TypeName() string {
-	return TypePair
+	return kern.TypePair
 }
 
-func (p *intPair) ToString(opt FmtOpt) string {
+func (p *intPair) ToString(opt kern.FmtOpt) string {
 	return fmt.Sprintf("(%d, %d)", p.a, p.b)
 }
 
@@ -41,21 +45,21 @@ func changeColonToRange(t *term) {
 	}
 }
 
-func evalRange(ctx ExprContext, opTerm *term) (v any, err error) {
+func evalRange(ctx kern.ExprContext, opTerm *term) (v any, err error) {
 	var leftValue, rightValue any
 
 	if len(opTerm.children) == 0 {
 		leftValue = int64(0)
 		rightValue = int64(-1)
 	} else if len(opTerm.children) == 1 {
-		if leftValue, err = opTerm.children[0].compute(ctx); err != nil {
+		if leftValue, err = opTerm.children[0].Compute(ctx); err != nil {
 			return
 		}
-		rightValue = int64(ConstLastIndex)
+		rightValue = int64(kern.ConstLastIndex)
 	} else if leftValue, rightValue, err = opTerm.evalInfix(ctx); err != nil {
 		return
 	}
-	if !(IsInteger(leftValue) && IsInteger(rightValue)) {
+	if !(kern.IsInteger(leftValue) && kern.IsInteger(rightValue)) {
 		// err = opTerm.errIncompatibleTypes(leftValue, rightValue)
 		err = errRangeInvalidSpecification(opTerm)
 		return

operator-rel.go

@@ -4,7 +4,11 @@
 // operator-rel.go
 package expr
 
-import "reflect"
+import (
+	"reflect"
+
+	"git.portale-stac.it/go-pkg/expr/kern"
+)
 
 //-------- equal term
 
@@ -18,25 +22,25 @@ func newEqualTerm(tk *Token) (inst *term) {
 	}
 }
 
-type deepFuncTemplate func(a, b any) (eq bool, err error)
+// type deepFuncTemplate func(a, b any) (eq bool, err error)
 
-func equals(a, b any, deepCmp deepFuncTemplate) (eq bool, err error) {
-	if isNumOrFract(a) && isNumOrFract(b) {
-		if IsNumber(a) && IsNumber(b) {
-			if IsInteger(a) && IsInteger(b) {
+func equals(a, b any, deepCmp kern.DeepFuncTemplate) (eq bool, err error) {
+	if kern.IsNumOrFract(a) && kern.IsNumOrFract(b) {
+		if kern.IsNumber(a) && kern.IsNumber(b) {
+			if kern.IsInteger(a) && kern.IsInteger(b) {
 				li, _ := a.(int64)
 				ri, _ := b.(int64)
 				eq = li == ri
 			} else {
-				eq = numAsFloat(a) == numAsFloat(b)
+				eq = kern.NumAsFloat(a) == kern.NumAsFloat(b)
 			}
 		} else {
 			var cmp int
-			if cmp, err = cmpAnyFract(a, b); err == nil {
+			if cmp, err = kern.CmpAnyFract(a, b); err == nil {
 				eq = cmp == 0
 			}
 		}
-	} else if deepCmp != nil && IsList(a) && IsList(b) {
+	} else if deepCmp != nil && kern.IsList(a) && kern.IsList(b) {
 		eq, err = deepCmp(a, b)
 	} else {
 		eq = reflect.DeepEqual(a, b)
@@ -45,7 +49,7 @@ func equals(a, b any, deepCmp deepFuncTemplate) (eq bool, err error) {
 	return
 }
 
-func evalEqual(ctx ExprContext, opTerm *term) (v any, err error) {
+func evalEqual(ctx kern.ExprContext, opTerm *term) (v any, err error) {
 	var leftValue, rightValue any
 
 	if leftValue, rightValue, err = opTerm.evalInfix(ctx); err != nil {
@@ -68,9 +72,9 @@ func newNotEqualTerm(tk *Token) (inst *term) {
 	}
 }
 
-func evalNotEqual(ctx ExprContext, opTerm *term) (v any, err error) {
+func evalNotEqual(ctx kern.ExprContext, opTerm *term) (v any, err error) {
 	if v, err = evalEqual(ctx, opTerm); err == nil {
-		b, _ := ToBool(v)
+		b, _ := kern.ToBool(v)
 		v = !b
 	}
 	return
@@ -89,37 +93,37 @@ func newLessTerm(tk *Token) (inst *term) {
 }
 
 func lessThan(self *term, a, b any) (isLess bool, err error) {
-	if isNumOrFract(a) && isNumOrFract(b) {
-		if IsNumber(a) && IsNumber(b) {
-			if IsInteger(a) && IsInteger(b) {
+	if kern.IsNumOrFract(a) && kern.IsNumOrFract(b) {
+		if kern.IsNumber(a) && kern.IsNumber(b) {
+			if kern.IsInteger(a) && kern.IsInteger(b) {
 				li, _ := a.(int64)
 				ri, _ := b.(int64)
 				isLess = li < ri
 			} else {
-				isLess = numAsFloat(a) < numAsFloat(b)
+				isLess = kern.NumAsFloat(a) < kern.NumAsFloat(b)
 			}
 		} else {
 			var cmp int
-			if cmp, err = cmpAnyFract(a, b); err == nil {
+			if cmp, err = kern.CmpAnyFract(a, b); err == nil {
 				isLess = cmp < 0
 			}
 		}
-	} else if IsString(a) && IsString(b) {
+	} else if kern.IsString(a) && kern.IsString(b) {
 		ls, _ := a.(string)
 		rs, _ := b.(string)
 		isLess = ls < rs
 		// Inclusion test
-	} else if IsList(a) && IsList(b) {
-		aList, _ := a.(*ListType)
-		bList, _ := b.(*ListType)
-		isLess = len(*aList) < len(*bList) && bList.contains(aList)
+	} else if kern.IsList(a) && kern.IsList(b) {
+		aList, _ := a.(*kern.ListType)
+		bList, _ := b.(*kern.ListType)
+		isLess = len(*aList) < len(*bList) && bList.Contains(aList)
 	} else {
 		err = self.errIncompatibleTypes(a, b)
 	}
 	return
 }
 
-func evalLess(ctx ExprContext, opTerm *term) (v any, err error) {
+func evalLess(ctx kern.ExprContext, opTerm *term) (v any, err error) {
 	var leftValue, rightValue any
 
 	if leftValue, rightValue, err = opTerm.evalInfix(ctx); err != nil {
@@ -144,8 +148,8 @@ func newLessEqualTerm(tk *Token) (inst *term) {
 func lessThanOrEqual(self *term, a, b any) (isLessEq bool, err error) {
 	if isLessEq, err = lessThan(self, a, b); err == nil {
 		if !isLessEq {
-			if IsList(a) && IsList(b) {
-				isLessEq, err = sameContent(a, b)
+			if kern.IsList(a) && kern.IsList(b) {
+				isLessEq, err = kern.SameContent(a, b)
 			} else {
 				isLessEq, err = equals(a, b, nil)
 			}
@@ -154,7 +158,7 @@ func lessThanOrEqual(self *term, a, b any) (isLessEq bool, err error) {
 	return
 }
 
-func evalLessEqual(ctx ExprContext, opTerm *term) (v any, err error) {
+func evalLessEqual(ctx kern.ExprContext, opTerm *term) (v any, err error) {
 	var leftValue, rightValue any
 
 	if leftValue, rightValue, err = opTerm.evalInfix(ctx); err != nil {
@@ -178,7 +182,7 @@ func newGreaterTerm(tk *Token) (inst *term) {
 	}
 }
 
-func evalGreater(ctx ExprContext, opTerm *term) (v any, err error) {
+func evalGreater(ctx kern.ExprContext, opTerm *term) (v any, err error) {
 	var leftValue, rightValue any
 
 	if leftValue, rightValue, err = opTerm.evalInfix(ctx); err != nil {
@@ -201,7 +205,7 @@ func newGreaterEqualTerm(tk *Token) (inst *term) {
 	}
 }
 
-func evalGreaterEqual(ctx ExprContext, opTerm *term) (v any, err error) {
+func evalGreaterEqual(ctx kern.ExprContext, opTerm *term) (v any, err error) {
 	var leftValue, rightValue any
 
 	if leftValue, rightValue, err = opTerm.evalInfix(ctx); err != nil {

operator-selector.go

@@ -4,6 +4,10 @@
 // operator-selector.go
 package expr
 
+import (
+	"git.portale-stac.it/go-pkg/expr/kern"
+)
+
 //-------- selector term
 
 func newSelectorTerm(tk *Token) (inst *term) {
@@ -16,7 +20,7 @@ func newSelectorTerm(tk *Token) (inst *term) {
 	}
 }
 
-func trySelectorCase(ctx ExprContext, exprValue, caseSel any, caseIndex int) (match bool, selectedValue any, err error) {
+func trySelectorCase(ctx kern.ExprContext, exprValue, caseSel any, caseIndex int) (match bool, selectedValue any, err error) {
 	caseData, _ := caseSel.(*selectorCase)
 	if caseData.filterList == nil {
 		selectedValue, err = caseData.caseExpr.Eval(ctx)
@@ -38,7 +42,7 @@ func trySelectorCase(ctx ExprContext, exprValue, caseSel any, caseIndex int) (ma
 		} else {
 			var caseValue any
 			for _, caseTerm := range filterList {
-				if caseValue, err = caseTerm.compute(ctx); err != nil || caseValue == exprValue {
+				if caseValue, err = caseTerm.Compute(ctx); err != nil || caseValue == exprValue {
 					selectedValue, err = caseData.caseExpr.Eval(ctx)
 					match = true
 					break
@@ -49,7 +53,7 @@ func trySelectorCase(ctx ExprContext, exprValue, caseSel any, caseIndex int) (ma
 	return
 }
 
-func evalSelector(ctx ExprContext, opTerm *term) (v any, err error) {
+func evalSelector(ctx kern.ExprContext, opTerm *term) (v any, err error) {
 	var exprValue any
 	var match bool
 
@@ -57,7 +61,7 @@ func evalSelector(ctx ExprContext, opTerm *term) (v any, err error) {
 		return
 	}
 	exprTerm := opTerm.children[0]
-	if exprValue, err = exprTerm.compute(ctx); err != nil {
+	if exprValue, err = exprTerm.Compute(ctx); err != nil {
 		return
 	}
 

operator-shift.go

@@ -4,6 +4,10 @@
 // operator-shift.go
 package expr
 
+import (
+	"git.portale-stac.it/go-pkg/expr/kern"
+)
+
 //-------- bit right shift term
 
 func newRightShiftTerm(tk *Token) (inst *term) {
@@ -17,7 +21,7 @@ func newRightShiftTerm(tk *Token) (inst *term) {
 }
 
 func bitRightShift(opTerm *term, leftValue, rightValue any) (v any, err error) {
-	if IsInteger(leftValue) && IsInteger(rightValue) {
+	if kern.IsInteger(leftValue) && kern.IsInteger(rightValue) {
 		leftInt := leftValue.(int64)
 		rightInt := rightValue.(int64)
 		v = leftInt >> rightInt
@@ -27,7 +31,7 @@ func bitRightShift(opTerm *term, leftValue, rightValue any) (v any, err error) {
 	return
 }
 
-func evalRightShift(ctx ExprContext, opTerm *term) (v any, err error) {
+func evalRightShift(ctx kern.ExprContext, opTerm *term) (v any, err error) {
 	var leftValue, rightValue any
 
 	if leftValue, rightValue, err = opTerm.evalInfix(ctx); err != nil {
@@ -49,7 +53,7 @@ func newLeftShiftTerm(tk *Token) (inst *term) {
 }
 
 func bitLeftShift(opTerm *term, leftValue, rightValue any) (v any, err error) {
-	if IsInteger(leftValue) && IsInteger(rightValue) {
+	if kern.IsInteger(leftValue) && kern.IsInteger(rightValue) {
 		leftInt := leftValue.(int64)
 		rightInt := rightValue.(int64)
 		v = leftInt << rightInt
@@ -59,7 +63,7 @@ func bitLeftShift(opTerm *term, leftValue, rightValue any) (v any, err error) {
 	return
 }
 
-func evalLeftShift(ctx ExprContext, opTerm *term) (v any, err error) {
+func evalLeftShift(ctx kern.ExprContext, opTerm *term) (v any, err error) {
 	var leftValue, rightValue any
 
 	if leftValue, rightValue, err = opTerm.evalInfix(ctx); err != nil {

operator-sign.go

@@ -4,6 +4,10 @@
 // operator-sign.go
 package expr
 
+import (
+	"git.portale-stac.it/go-pkg/expr/kern"
+)
+
 //-------- plus sign term
 
 func newPlusSignTerm(tk *Token) (inst *term) {
@@ -28,21 +32,21 @@ func newMinusSignTerm(tk *Token) (inst *term) {
 	}
 }
 
-func evalSign(ctx ExprContext, opTerm *term) (v any, err error) {
+func evalSign(ctx kern.ExprContext, opTerm *term) (v any, err error) {
 	var rightValue any
 
 	if rightValue, err = opTerm.evalPrefix(ctx); err != nil {
 		return
 	}
 
-	if IsFloat(rightValue) {
+	if kern.IsFloat(rightValue) {
 		if opTerm.tk.Sym == SymChangeSign {
 			f, _ := rightValue.(float64)
 			v = -f
 		} else {
 			v = rightValue
 		}
-	} else if IsInteger(rightValue) {
+	} else if kern.IsInteger(rightValue) {
 		if opTerm.tk.Sym == SymChangeSign {
 			i, _ := rightValue.(int64)
 			v = -i
@@ -50,7 +54,7 @@ func evalSign(ctx ExprContext, opTerm *term) (v any, err error) {
 			v = rightValue
 		}
 	} else {
-		err = opTerm.errIncompatibleType(rightValue)
+		err = opTerm.errIncompatiblePrefixPostfixType(rightValue)
 	}
 	return
 }

operator-sum.go

@@ -7,6 +7,8 @@ package expr
 import (
 	"fmt"
 	"slices"
+
+	"git.portale-stac.it/go-pkg/expr/kern"
 )
 
 //-------- plus term
@@ -22,46 +24,46 @@ func newPlusTerm(tk *Token) (inst *term) {
 }
 
 func sumValues(plusTerm *term, leftValue, rightValue any) (v any, err error) {
-	if (IsString(leftValue) && isNumberString(rightValue)) || (IsString(rightValue) && isNumberString(leftValue)) {
+	if (kern.IsString(leftValue) && kern.IsNumberString(rightValue)) || (kern.IsString(rightValue) && kern.IsNumberString(leftValue)) {
 		v = fmt.Sprintf("%v%v", leftValue, rightValue)
-	} else if IsNumber(leftValue) && IsNumber(rightValue) {
-		if IsFloat(leftValue) || IsFloat(rightValue) {
-			v = numAsFloat(leftValue) + numAsFloat(rightValue)
+	} else if kern.IsNumber(leftValue) && kern.IsNumber(rightValue) {
+		if kern.IsFloat(leftValue) || kern.IsFloat(rightValue) {
+			v = kern.NumAsFloat(leftValue) + kern.NumAsFloat(rightValue)
 		} else {
 			leftInt, _ := leftValue.(int64)
 			rightInt, _ := rightValue.(int64)
 			v = leftInt + rightInt
 		}
-	} else if IsList(leftValue) && IsList(rightValue) {
-		var leftList, rightList *ListType
-		leftList, _ = leftValue.(*ListType)
-		rightList, _ = rightValue.(*ListType)
+	} else if kern.IsList(leftValue) && kern.IsList(rightValue) {
+		var leftList, rightList *kern.ListType
+		leftList, _ = leftValue.(*kern.ListType)
+		rightList, _ = rightValue.(*kern.ListType)
 
-		sumList := make(ListType, 0, len(*leftList)+len(*rightList))
+		sumList := make(kern.ListType, 0, len(*leftList)+len(*rightList))
 		sumList = append(sumList, *leftList...)
 		sumList = append(sumList, *rightList...)
 		v = &sumList
-	} else if (isFraction(leftValue) && IsNumber(rightValue)) || (isFraction(rightValue) && IsNumber(leftValue)) {
-		if IsFloat(leftValue) || IsFloat(rightValue) {
-			v = numAsFloat(leftValue) + numAsFloat(rightValue)
+	} else if (kern.IsFraction(leftValue) && kern.IsNumber(rightValue)) || (kern.IsFraction(rightValue) && kern.IsNumber(leftValue)) {
+		if kern.IsFloat(leftValue) || kern.IsFloat(rightValue) {
+			v = kern.NumAsFloat(leftValue) + kern.NumAsFloat(rightValue)
 		} else {
-			v, err = sumAnyFract(leftValue, rightValue)
+			v, err = kern.SumAnyFract(leftValue, rightValue)
 		}
-	} else if IsDict(leftValue) && IsDict(rightValue) {
-		leftDict, _ := leftValue.(*DictType)
-		rightDict, _ := rightValue.(*DictType)
-		c := leftDict.clone()
-		c.merge(rightDict)
+	} else if kern.IsDict(leftValue) && kern.IsDict(rightValue) {
+		leftDict, _ := leftValue.(*kern.DictType)
+		rightDict, _ := rightValue.(*kern.DictType)
+		c := leftDict.Clone()
+		c.Merge(rightDict)
 		v = c
-	} else if isFraction(leftValue) && isFraction(rightValue) {
-		v, err = sumAnyFract(leftValue, rightValue)
+	} else if kern.IsFraction(leftValue) && kern.IsFraction(rightValue) {
+		v, err = kern.SumAnyFract(leftValue, rightValue)
 	} else {
 		err = plusTerm.errIncompatibleTypes(leftValue, rightValue)
 	}
 	return v, err
 }
 
-func evalPlus(ctx ExprContext, plusTerm *term) (v any, err error) {
+func evalPlus(ctx kern.ExprContext, plusTerm *term) (v any, err error) {
 	var leftValue, rightValue any
 
 	if leftValue, rightValue, err = plusTerm.evalInfix(ctx); err != nil {
@@ -84,20 +86,20 @@ func newMinusTerm(tk *Token) (inst *term) {
 }
 
 func diffValues(minusTerm *term, leftValue, rightValue any) (v any, err error) {
-	if isNumOrFract(leftValue) && isNumOrFract(rightValue) {
-		if IsFloat(leftValue) || IsFloat(rightValue) {
-			v = numAsFloat(leftValue) - numAsFloat(rightValue)
-		} else if isFraction(leftValue) || isFraction(rightValue) {
-			v, err = subAnyFract(leftValue, rightValue)
+	if kern.IsNumOrFract(leftValue) && kern.IsNumOrFract(rightValue) {
+		if kern.IsFloat(leftValue) || kern.IsFloat(rightValue) {
+			v = kern.NumAsFloat(leftValue) - kern.NumAsFloat(rightValue)
+		} else if kern.IsFraction(leftValue) || kern.IsFraction(rightValue) {
+			v, err = kern.SubAnyFract(leftValue, rightValue)
 		} else {
 			leftInt, _ := leftValue.(int64)
 			rightInt, _ := rightValue.(int64)
 			v = leftInt - rightInt
 		}
-	} else if IsList(leftValue) && IsList(rightValue) {
-		leftList, _ := leftValue.(*ListType)
-		rightList, _ := rightValue.(*ListType)
-		diffList := make(ListType, 0, len(*leftList)-len(*rightList))
+	} else if kern.IsList(leftValue) && kern.IsList(rightValue) {
+		leftList, _ := leftValue.(*kern.ListType)
+		rightList, _ := rightValue.(*kern.ListType)
+		diffList := make(kern.ListType, 0, len(*leftList)-len(*rightList))
 		for _, item := range *leftList {
 			if slices.Index(*rightList, item) < 0 {
 				diffList = append(diffList, item)
@@ -110,7 +112,7 @@ func diffValues(minusTerm *term, leftValue, rightValue any) (v any, err error) {
 	return
 }
 
-func evalMinus(ctx ExprContext, minusTerm *term) (v any, err error) {
+func evalMinus(ctx kern.ExprContext, minusTerm *term) (v any, err error) {
 	var leftValue, rightValue any
 
 	if leftValue, rightValue, err = minusTerm.evalInfix(ctx); err != nil {

operator-unset.go

@@ -4,7 +4,11 @@
 // operator-unset.go
 package expr
 
-import "strings"
+import (
+	"strings"
+
+	"git.portale-stac.it/go-pkg/expr/kern"
+)
 
 //-------- unset term
 
@@ -18,7 +22,7 @@ func newUnsetTerm(tk *Token) (inst *term) {
 	}
 }
 
-func deleteContextItem(ctx ExprContext, opTerm *term, item any) (deleted bool, err error) {
+func deleteContextItem(ctx kern.ExprContext, opTerm *term, item any) (deleted bool, err error) {
 	if name, ok := item.(string); ok {
 		var size int
 		if strings.HasSuffix(name, "()") {
@@ -31,12 +35,12 @@ func deleteContextItem(ctx ExprContext, opTerm *term, item any) (deleted bool, e
 			deleted = ctx.VarCount() < size
 		}
 	} else {
-		err = opTerm.errIncompatibleType(item)
+		err = opTerm.errIncompatiblePrefixPostfixType(item)
 	}
 	return
 }
 
-func evalUnset(ctx ExprContext, opTerm *term) (v any, err error) {
+func evalUnset(ctx kern.ExprContext, opTerm *term) (v any, err error) {
 	var childValue any
 	var deleted bool
 
@@ -45,8 +49,8 @@ func evalUnset(ctx ExprContext, opTerm *term) (v any, err error) {
 	}
 
 	count := 0
-	if IsList(childValue) {
-		list, _ := childValue.(*ListType)
+	if kern.IsList(childValue) {
+		list, _ := childValue.(*kern.ListType)
 		for _, item := range *list {
 			if deleted, err = deleteContextItem(ctx, opTerm, item); err != nil {
 				break

parser.go

@@ -104,7 +104,7 @@ func (parser *parser) parseFuncDef(scanner *scanner) (tree *term, err error) {
 			param := newTerm(tk)
 			if len(args) > 0 {
 				if pos := paramAlreadyDefined(args, param); pos > 0 {
-					err = tk.Errorf("parameter %q at position %d already defined at position %d", param.source(), len(args)+1, pos)
+					err = tk.Errorf("parameter %q at position %d already defined at position %d", param.Source(), len(args)+1, pos)
 					break
 				}
 			}
@@ -155,7 +155,7 @@ func (parser *parser) parseFuncDef(scanner *scanner) (tree *term, err error) {
 func paramAlreadyDefined(args []*term, param *term) (position int) {
 	position = 0
 	for i, arg := range args {
-		if arg.source() == param.source() {
+		if arg.Source() == param.Source() {
 			position = i + 1
 		}
 	}
@@ -382,6 +382,15 @@ func (parser *parser) parseItem(scanner *scanner, ctx parserContext, termSymbols
 }
 
 func (parser *parser) Parse(scanner *scanner, termSymbols ...Symbol) (tree *ast, err error) {
+	defer func() {
+		if r := recover(); r != nil {
+			if errVal, ok := r.(error); ok {
+				err = errVal
+			} else {
+				err = errors.New("unexpected error while parsing the expression")
+			}
+		}
+	}()
 	termSymbols = append(termSymbols, SymEos)
 	return parser.parseGeneral(scanner, allowMultiExpr, termSymbols...)
 }
@@ -397,7 +406,7 @@ func couldBeACollection(t *term) bool {
 func listSubTree(tree *ast, listTerm *term, allowIndeces bool) (root *term, err error) {
 	var tk *Token
 	if allowIndeces {
-		tk = NewToken(listTerm.tk.row, listTerm.tk.col, SymIndex, listTerm.source())
+		tk = NewToken(listTerm.tk.row, listTerm.tk.col, SymIndex, listTerm.Source())
 		root = newTerm(tk)
 		if err = tree.addTerm(root); err == nil {
 			err = tree.addTerm(listTerm)
@@ -455,15 +464,6 @@ func (parser *parser) parseGeneral(scanner *scanner, ctx parserContext, termSymb
 		//fmt.Println("Token:", tk)
 		if firstToken {
 			changePrefix(tk)
-			// if tk.Sym == SymMinus {
-			// 	tk.Sym = SymChangeSign
-			// } else if tk.Sym == SymPlus {
-			// 	tk.Sym = SymUnchangeSign
-			// } else if tk.IsSymbol(SymStar) {
-			// 	tk.SetSymbol(SymDereference)
-			// } else if tk.IsSymbol(SymExclamation) {
-			// 	tk.SetSymbol(SymNot)
-			// }
 			firstToken = false
 		}
 
@@ -471,12 +471,13 @@ func (parser *parser) parseGeneral(scanner *scanner, ctx parserContext, termSymb
 		case SymOpenRound:
 			var subTree *ast
 			if subTree, err = parser.parseGeneral(scanner, ctx, SymClosedRound); err == nil {
-				exprTerm := newExprTerm(subTree.root)
-				err = tree.addTerm(exprTerm)
-				currentTerm = exprTerm
-				// subTree.root.priority = priValue
-				// err = tree.addTerm(newExprTerm(subTree.root))
-				// currentTerm = subTree.root
+				if subTree.root == nil {
+					err = tk.ErrorExpectedGotString("expression", "()")
+				} else {
+					exprTerm := newExprTerm(subTree.root)
+					err = tree.addTerm(exprTerm)
+					currentTerm = exprTerm
+				}
 			}
 		case SymFuncCall:
 			var funcCallTerm *term

plugins.go

@@ -10,6 +10,8 @@ import (
 	"os"
 	"plugin"
 	"strings"
+
+	"git.portale-stac.it/go-pkg/expr/kern"
 )
 
 var pluginRegister map[string]*plugin.Plugin
@@ -39,12 +41,12 @@ func makePluginName(name string) (decorated string) {
 	return
 }
 
-func importPlugin( /*ctx ExprContext,*/ dirList []string, name string) (err error) {
+func importPlugin(ctx kern.ExprContext, dirList []string, name string) (err error) {
 	var filePath string
 	var p *plugin.Plugin
 	var sym plugin.Symbol
 	var moduleName string
-	var importFunc func(ExprContext)
+	var importFunc func(kern.ExprContext)
 	var ok bool
 
 	decoratedName := makePluginName(name)
@@ -71,7 +73,7 @@ func importPlugin( /*ctx ExprContext,*/ dirList []string, name string) (err erro
 	}
 	if deps := *sym.(*[]string); len(deps) > 0 {
 		// var count int
-		if err = loadModules(dirList, deps); err != nil {
+		if err = loadModules(ctx, dirList, deps); err != nil {
 			return
 		}
 	}
@@ -80,33 +82,35 @@ func importPlugin( /*ctx ExprContext,*/ dirList []string, name string) (err erro
 		return
 	}
 
-	if importFunc, ok = sym.(func(ExprContext)); !ok {
+	if importFunc, ok = sym.(func(kern.ExprContext)); !ok {
 		err = fmt.Errorf("plugin %q does not provide a valid import function", decoratedName)
 		return
 	}
 
 	registerPlugin(moduleName, p)
-	importFunc(globalCtx)
+	if globalCtx := ctx.GetGlobal(); globalCtx != nil {
+		importFunc(globalCtx)
+	}
 
 	return
 }
 
-func importPluginFromSearchPath(name any) (count int, err error) {
+func importPluginFromSearchPath(ctx kern.ExprContext, name any) (count int, err error) {
 	var moduleSpec any
-	var it Iterator
-	dirList := buildSearchDirList("plugin", ENV_EXPR_PLUGIN_PATH)
+	var it kern.Iterator
+	dirList := buildSearchDirList(ctx, "plugin", ENV_EXPR_PLUGIN_PATH)
 	count = 0
 	if it, err = NewIterator(name); err != nil {
 		return
 	}
 	for moduleSpec, err = it.Next(); err == nil; moduleSpec, err = it.Next() {
 		if module, ok := moduleSpec.(string); ok {
-			if err = importPlugin(dirList, module); err != nil {
+			if err = importPlugin(ctx, dirList, module); err != nil {
 				break
 			}
 			count++
 		} else {
-			err = fmt.Errorf("expected string as item nr %d, got %s", it.Index()+1, TypeName(moduleSpec))
+			err = fmt.Errorf("expected string as item nr %d, got %s", it.Index()+1, kern.TypeName(moduleSpec))
 			break
 		}
 	}
@@ -116,10 +120,10 @@ func importPluginFromSearchPath(name any) (count int, err error) {
 	return
 }
 
-func loadModules(dirList []string, moduleNames []string) (err error) {
+func loadModules(ctx kern.ExprContext, dirList []string, moduleNames []string) (err error) {
 	for _, name := range moduleNames {
-		if err1 := importPlugin(dirList, name); err1 != nil {
-			if !ImportInContext(name) {
+		if err1 := importPlugin(ctx, dirList, name); err1 != nil {
+			if !ImportInContext(ctx, name) {
 				err = err1
 				break
 			}

scanner.go

@@ -11,6 +11,8 @@ import (
 	"io"
 	"strconv"
 	"strings"
+
+	"git.portale-stac.it/go-pkg/expr/kern"
 )
 
 type scanner struct {
@@ -503,7 +505,7 @@ func (scanner *scanner) parseNumber(firstCh byte) (tk *Token) {
 		if sym == SymFloat {
 			value, err = strconv.ParseFloat(txt, 64)
 		} else if sym == SymFraction {
-			value, err = makeGeneratingFraction(txt)
+			value, err = kern.MakeGeneratingFraction(txt)
 		} else {
 			value, err = strconv.ParseInt(txt, numBase, 64)
 		}

simple-store.go

@@ -7,43 +7,63 @@ package expr
 import (
 	"fmt"
 	"slices"
+
+	"git.portale-stac.it/go-pkg/expr/kern"
+	"git.portale-stac.it/go-pkg/expr/util"
 	// "strings"
 )
 
 type SimpleStore struct {
-	parent    ExprContext
+	global    kern.ExprContext
+	parent    kern.ExprContext
 	varStore  map[string]any
-	funcStore map[string]ExprFunc
+	funcStore map[string]kern.ExprFunc
 }
 
 func NewSimpleStore() *SimpleStore {
+	global := InitGlobal()
+	ctx := &SimpleStore{
+		global:    global,
+		varStore:  make(map[string]any),
+		funcStore: make(map[string]kern.ExprFunc),
+	}
+	return ctx
+}
+
+func NewSimpleStoreWithoutGlobalContext() *SimpleStore {
 	ctx := &SimpleStore{
 		varStore:  make(map[string]any),
-		funcStore: make(map[string]ExprFunc),
+		funcStore: make(map[string]kern.ExprFunc),
 	}
 	return ctx
 }
 
 func (ss *SimpleStore) Init() {
 	ss.varStore = make(map[string]any)
-	ss.funcStore = make(map[string]ExprFunc)
+	ss.funcStore = make(map[string]kern.ExprFunc)
 }
 
-func filterRefName(name string) bool  { return name[0] != '@' }
+func filterRefName(name string) bool { return name[0] != '@' }
+
 //func filterPrivName(name string) bool { return name[0] != '_' }
 
-func (ctx *SimpleStore) SetParent(parentCtx ExprContext) {
+func (ctx *SimpleStore) SetParent(parentCtx kern.ExprContext) {
 	ctx.parent = parentCtx
 }
 
-func (ctx *SimpleStore) GetParent() ExprContext {
+func (ctx *SimpleStore) GetParent() kern.ExprContext {
 	return ctx.parent
 }
 
-func (ctx *SimpleStore) Clone() ExprContext {
+func (ctx *SimpleStore) GetGlobal() (globalCtx kern.ExprContext) {
+	return ctx.global
+}
+
+func (ctx *SimpleStore) Clone() kern.ExprContext {
 	clone := &SimpleStore{
-		varStore:  CloneFilteredMap(ctx.varStore, filterRefName),
-		funcStore: CloneFilteredMap(ctx.funcStore, filterRefName),
+		global:    ctx.global,
+		varStore:  util.CloneFilteredMap(ctx.varStore, filterRefName),
+		funcStore: util.CloneFilteredMap(ctx.funcStore, filterRefName),
 	}
 	return clone
 }
@@ -57,19 +77,19 @@ func (ctx *SimpleStore) Clone() ExprContext {
 // 	}
 // }
 
-func (ctx *SimpleStore) ToString(opt FmtOpt) string {
+func (ctx *SimpleStore) ToString(opt kern.FmtOpt) string {
 	dict := ctx.ToDict()
 	return dict.ToString(opt)
 }
 
-func (ctx *SimpleStore) varsToDict(dict *DictType) *DictType {
+func (ctx *SimpleStore) varsToDict(dict *kern.DictType) *kern.DictType {
 	names := ctx.EnumVars(nil)
 	slices.Sort(names)
 	for _, name := range ctx.EnumVars(nil) {
 		value, _ := ctx.GetVar(name)
-		if f, ok := value.(Formatter); ok {
+		if f, ok := value.(kern.Formatter); ok {
 			(*dict)[name] = f.ToString(0)
-		} else if _, ok = value.(Functor); ok {
+		} else if _, ok = value.(kern.Functor); ok {
 			(*dict)[name] = "func(){}"
 		} else {
 			(*dict)[name] = fmt.Sprintf("%v", value)
@@ -78,12 +98,12 @@ func (ctx *SimpleStore) varsToDict(dict *DictType) *DictType {
 	return dict
 }
 
-func (ctx *SimpleStore) funcsToDict(dict *DictType) *DictType {
+func (ctx *SimpleStore) funcsToDict(dict *kern.DictType) *kern.DictType {
 	names := ctx.EnumFuncs(func(name string) bool { return true })
 	slices.Sort(names)
 	for _, name := range names {
 		value, _ := ctx.GetFuncInfo(name)
-		if formatter, ok := value.(Formatter); ok {
+		if formatter, ok := value.(kern.Formatter); ok {
 			(*dict)[name] = formatter.ToString(0)
 		} else {
 			(*dict)[name] = fmt.Sprintf("%v", value)
@@ -92,20 +112,23 @@ func (ctx *SimpleStore) funcsToDict(dict *DictType) *DictType {
 	return dict
 }
 
-func (ctx *SimpleStore) ToDict() (dict *DictType) {
-	dict = MakeDict()
-	(*dict)["variables"] = ctx.varsToDict(MakeDict())
-	(*dict)["functions"] = ctx.funcsToDict(MakeDict())
+func (ctx *SimpleStore) ToDict() (dict *kern.DictType) {
+	dict = kern.MakeDict()
+	(*dict)["variables"] = ctx.varsToDict(kern.MakeDict())
+	(*dict)["functions"] = ctx.funcsToDict(kern.MakeDict())
 	return
 }
 
-func (ctx *SimpleStore) GetVar(varName string) (v any, exists bool) {
-	v, exists = ctx.varStore[varName]
+func (ctx *SimpleStore) GetVar(varName string) (value any, exists bool) {
+	if value, exists = ctx.varStore[varName]; !exists && ctx.global != nil {
+		value, exists = ctx.global.GetVar(varName)
+	}
+
 	return
 }
 
 func (ctx *SimpleStore) GetLast() (v any) {
-	v = ctx.varStore["last"]
+	v = ctx.varStore[kern.ControlLastResult]
 	return
 }
 
@@ -116,7 +139,7 @@ func (ctx *SimpleStore) UnsafeSetVar(varName string, value any) {
 
 func (ctx *SimpleStore) SetVar(varName string, value any) {
 	// fmt.Printf("[%p] SetVar(%v, %v)\n", ctx, varName, value)
-	if allowedValue, ok := fromGenericAny(value); ok {
+	if allowedValue, ok := util.FromGenericAny(value); ok {
 		ctx.varStore[varName] = allowedValue
 	} else {
 		panic(fmt.Errorf("unsupported type %T of value %v", value, value))
@@ -145,16 +168,42 @@ func (ctx *SimpleStore) DeleteVar(varName string) {
 	delete(ctx.varStore, varName)
 }
 
-func (ctx *SimpleStore) GetFuncInfo(name string) (info ExprFunc, exists bool) {
-	info, exists = ctx.funcStore[name]
+func (ctx *SimpleStore) GetFuncInfo(name string) (info kern.ExprFunc, exists bool) {
+	info, exists, _ = ctx.GetFuncInfoAndOwner(name)
 	return
 }
 
-func (ctx *SimpleStore) RegisterFuncInfo(info ExprFunc) {
+func (ctx *SimpleStore) GetFuncInfoAndOwner(name string) (info kern.ExprFunc, exists bool, ownerCtx kern.ExprContext) {
+	if len(name) > 0 {
+		if info, exists = ctx.GetLocalFuncInfo(name); exists {
+			ownerCtx = ctx
+		} else if globalCtx := ctx.GetGlobal(); globalCtx != nil {
+			if info, exists = globalCtx.GetFuncInfo(name); exists {
+				ownerCtx = globalCtx
+			}
+		}
+	}
+	return
+}
+
+func (ctx *SimpleStore) GetLocalFuncInfo(name string) (info kern.ExprFunc, exists bool) {
+	var v any
+	if len(name) > 0 {
+		if v, exists = ctx.GetVar(name); exists && kern.IsFunctor(v) {
+			f, _ := v.(kern.Functor)
+			info = f.GetFunc()
+		} else {
+			info, exists = ctx.funcStore[name]
+		}
+	}
+	return
+}
+
+func (ctx *SimpleStore) RegisterFuncInfo(info kern.ExprFunc) {
 	ctx.funcStore[info.Name()], _ = info.(*funcInfo)
 }
 
-func (ctx *SimpleStore) RegisterFunc(name string, functor Functor, returnType string, params []ExprFuncParam)  (exprFunc ExprFunc, err error) {
+func (ctx *SimpleStore) RegisterFunc(name string, functor kern.Functor, returnType string, params []kern.ExprFuncParam) (exprFunc kern.ExprFunc, err error) {
 	var info *funcInfo
 	if info, err = newFuncInfo(name, functor, returnType, params); err == nil {
 		ctx.funcStore[name] = info
@@ -186,7 +235,7 @@ func (ctx *SimpleStore) DeleteFunc(funcName string) {
 }
 
 func (ctx *SimpleStore) Call(name string, args map[string]any) (result any, err error) {
-	if info, exists := GetLocalFuncInfo(ctx, name); exists {
+	if info, exists := ctx.GetLocalFuncInfo(name); exists {
 		functor := info.Functor()
 		result, err = functor.InvokeNamed(ctx, name, args)
 	} else {

symbol-map.go

@@ -182,21 +182,49 @@ func StringEndsWithOperator(s string) bool {
 	return endingOperator(s) != SymNone
 }
 
+// func endingOperator(s string) (sym Symbol) {
+// 	var matchLength = 0
+// 	sym = SymNone
+// 	lower := strings.TrimRight(strings.ToLower(s), " \t")
+// 	for symbol, spec := range symbolMap {
+// 		if strings.HasSuffix(lower, spec.repr) {
+// 			if len(spec.repr) > matchLength {
+// 				matchLength = len(spec.repr)
+// 				if spec.kind == symClassOperator && (spec.opType == posInfix || spec.opType == posPrefix) {
+// 					sym = symbol
+// 				} else {
+// 					sym = SymNone
+// 				}
+// 			}
+// 		}
+// 	}
+// 	return
+// }
+
 func endingOperator(s string) (sym Symbol) {
 	var matchLength = 0
+	var repr string
 	sym = SymNone
 	lower := strings.TrimRight(strings.ToLower(s), " \t")
 	for symbol, spec := range symbolMap {
-		if strings.HasSuffix(lower, spec.repr) {
-			if len(spec.repr) > matchLength {
-				matchLength = len(spec.repr)
-				if spec.kind == symClassOperator && (spec.opType == posInfix || spec.opType == posPrefix) {
+		if len(spec.repr) > matchLength || repr == spec.repr {
+			if strings.HasSuffix(lower, spec.repr) {
+				if isNotEndingSymbol(spec) && repr != spec.repr {
+					repr = spec.repr
+					matchLength = len(spec.repr)
 					sym = symbol
 				} else {
 					sym = SymNone
+					break
+					// matchLength = 0
 				}
 			}
 		}
 	}
 	return
 }
+
+func isNotEndingSymbol(spec symbolSpec) bool {
+	return (spec.kind == symClassOperator && (spec.opType == posInfix || spec.opType == posPrefix)) ||
+		(spec.kind == symClassParenthesis && spec.opType == posPrefix)
+}

t_bool_test.go

@@ -7,6 +7,8 @@ package expr
 import (
 	"errors"
 	"testing"
+
+	"git.portale-stac.it/go-pkg/expr/kern"
 )
 
 func TestBool(t *testing.T) {
@@ -19,10 +21,10 @@ func TestBool(t *testing.T) {
 		/*   5 */ {`not "true"`, false, nil},
 		/*   6 */ {`not "false"`, false, nil},
 		/*   7 */ {`not ""`, true, nil},
-		/*   8 */ {`not []`, nil, errors.New(`[1:4] prefix/postfix operator "NOT" do not support operand '[]' [list]`)},
+		/*   8 */ {`not []`, nil, errors.New(`[1:4] prefix/postfix operator "NOT" does not support operand '[]' [list]`)},
 		/*   9 */ {`true and false`, false, nil},
 		/*  10 */ {`true and []`, nil, errors.New(`[1:9] left operand 'true' [bool] and right operand '[]' [list] are not compatible with operator "AND"`)},
-		/*  11 */ {`[] and false`, nil, errors.New(`got list as left operand type of 'AND' operator, it must be bool`)},
+		/*  11 */ {`[] and false`, nil, errors.New(`[1:7] operator "AND" does not support operand '[]' [list] on its left side`)},
 		/*  12 */ {`true or false`, true, nil},
 		/*  13 */ {`true or []`, true, nil},
 		/*  14 */ {`[] or false`, nil, errors.New(`got list as left operand type of 'OR' operator, it must be bool`)},
@@ -32,7 +34,7 @@ func TestBool(t *testing.T) {
 
 	// t.Setenv("EXPR_PATH", ".")
 
-	// runTestSuiteSpec(t, section, inputs, 15)
+	// runTestSuiteSpec(t, section, inputs, 13)
 	runTestSuite(t, section, inputs)
 }
 
@@ -46,7 +48,7 @@ func TestBoolNoShortcut(t *testing.T) {
 		/*   5 */ {`not "true"`, false, nil},
 		/*   6 */ {`not "false"`, false, nil},
 		/*   7 */ {`not ""`, true, nil},
-		/*   8 */ {`not []`, nil, `[1:4] prefix/postfix operator "NOT" do not support operand '[]' [list]`},
+		/*   8 */ {`not []`, nil, `[1:4] prefix/postfix operator "NOT" does not support operand '[]' [list]`},
 		/*   9 */ {`true and false`, false, nil},
 		/*  10 */ {`true and []`, nil, `[1:9] left operand 'true' [bool] and right operand '[]' [list] are not compatible with operator "AND"`},
 		/*  11 */ {`[] and false`, nil, `[1:7] left operand '[]' [list] and right operand 'false' [bool] are not compatible with operator "AND"`},
@@ -58,10 +60,10 @@ func TestBoolNoShortcut(t *testing.T) {
 	// t.Setenv("EXPR_PATH", ".")
 
 	ctx := NewSimpleStore()
-	current := SetCtrl(ctx, ControlBoolShortcut, false)
+	current := kern.SetCtrl(ctx, kern.ControlBoolShortcut, false)
 
 	// runCtxTestSuiteSpec(t, ctx, section, inputs, 1)
 	runCtxTestSuite(t, ctx, section, inputs)
 
-	SetCtrl(ctx, ControlBoolShortcut, current)
+	kern.SetCtrl(ctx, kern.ControlBoolShortcut, current)
 }

t_builtin-base_test.go

@@ -6,6 +6,8 @@ package expr
 
 import (
 	"testing"
+
+	"git.portale-stac.it/go-pkg/expr/kern"
 )
 
 func TestFuncBase(t *testing.T) {
@@ -33,10 +35,10 @@ func TestFuncBase(t *testing.T) {
 		/*  19 */ {`isFract(1:3)`, true, nil},
 		/*  20 */ {`isFract(3:1)`, false, nil},
 		/*  21 */ {`isRational(3:1)`, true, nil},
-		/*  22 */ {`fract("2.2(3)")`, newFraction(67, 30), nil},
-		/*  23 */ {`fract("1.21(3)")`, newFraction(91, 75), nil},
-		/*  24 */ {`fract(1.21(3))`, newFraction(91, 75), nil},
-		/*  25 */ {`fract(1.21)`, newFraction(121, 100), nil},
+		/*  22 */ {`fract("2.2(3)")`, kern.NewFraction(67, 30), nil},
+		/*  23 */ {`fract("1.21(3)")`, kern.NewFraction(91, 75), nil},
+		/*  24 */ {`fract(1.21(3))`, kern.NewFraction(91, 75), nil},
+		/*  25 */ {`fract(1.21)`, kern.NewFraction(121, 100), nil},
 		/*  26 */ {`dec(2)`, float64(2), nil},
 		/*  27 */ {`dec(2.0)`, float64(2), nil},
 		/*  28 */ {`dec("2.0")`, float64(2), nil},
@@ -45,8 +47,8 @@ func TestFuncBase(t *testing.T) {
 		/*  31 */ {`dec()`, nil, `dec(): too few params -- expected 1, got 0`},
 		/*  32 */ {`dec(1,2,3)`, nil, `dec(): too many params -- expected 1, got 3`},
 		/*  33 */ {`isBool(false)`, true, nil},
-		/*  34 */ {`fract(1:2)`, newFraction(1, 2), nil},
-		/*  35 */ {`fract(12,2)`, newFraction(6, 1), nil},
+		/*  34 */ {`fract(1:2)`, kern.NewFraction(1, 2), nil},
+		/*  35 */ {`fract(12,2)`, kern.NewFraction(6, 1), nil},
 		/*  36 */ {`bool(2)`, true, nil},
 		/*  37 */ {`bool(1:2)`, true, nil},
 		/*  38 */ {`bool(1.0)`, true, nil},

t_builtin-fmt_test.go

@@ -9,6 +9,8 @@ import (
 	"bytes"
 	"fmt"
 	"testing"
+
+	"git.portale-stac.it/go-pkg/expr/kern"
 )
 
 func TestFuncFmt(t *testing.T) {
@@ -37,11 +39,11 @@ func TestFmt(t *testing.T) {
 
 	var b bytes.Buffer
 	ctx := NewSimpleStore()
-	currentStdout := SetCtrl(ctx, ControlStdout, &b)
+	currentStdout := kern.SetCtrl(ctx, kern.ControlStdout, &b)
 
 	runCtxTestSuite(t, ctx, section, inputs)
 
-	SetCtrl(ctx, ControlStdout, currentStdout)
+	kern.SetCtrl(ctx, kern.ControlStdout, currentStdout)
 	if b.String() != text+"\n" {
 		t.Errorf("println(): Got: %q, Want: %q", b.String(), text+"\n")
 	}

t_builtin-iterator_test.go

@@ -14,7 +14,7 @@ func TestFuncRun(t *testing.T) {
 	inputs := []inputType{
 		/*   1 */ {`builtin "iterator"; it=$(1,2,3); run(it)`, nil, nil},
 		/*   2 */ {`builtin "iterator"; run($(1,2,3), func(index,item){item+10})`, nil, nil},
-		/*   3 */ {`builtin "iterator"; run($(1,2,3), func(index,item){status=status+item; true}, {"status":0})`, int64(6), nil},
+		/*   3 */ {`builtin "iterator"; run($(4), func(index,item){status=status+item; true}, {"status":0})`, int64(6), nil},
 		/*   4 */ {`builtin ["iterator", "fmt"]; run($(1,2,3), func(index,item){println(item+10)})`, nil, nil},
 		/*   5 */ {`builtin "iterator"; run(nil)`, nil, `paramter "iterator" must be an iterator, passed <nil> [nil]`},
 		/*   6 */ {`builtin "iterator"; run($(1,2,3), nil)`, nil, nil},
@@ -26,6 +26,6 @@ func TestFuncRun(t *testing.T) {
 
 	//t.Setenv("EXPR_PATH", ".")
 
-	runTestSuiteSpec(t, section, inputs, 10)
-	// runTestSuite(t, section, inputs)
+	// runTestSuiteSpec(t, section, inputs, 3)
+	runTestSuite(t, section, inputs)
 }

t_builtin-string_test.go

@@ -6,6 +6,8 @@ package expr
 
 import (
 	"testing"
+
+	"git.portale-stac.it/go-pkg/expr/kern"
 )
 
 func TestFuncString(t *testing.T) {
@@ -28,7 +30,7 @@ func TestFuncString(t *testing.T) {
 		/*  14 */ {`builtin "string"; strEndsWith("0123456789", "xyz", "789")`, true, nil},
 		/*  15 */ {`builtin "string"; strEndsWith("0123456789", "xyz", "0125")`, false, nil},
 		/*  16 */ {`builtin "string"; strEndsWith("0123456789")`, nil, `strEndsWith(): too few params -- expected 2 or more, got 1`},
-		/*  17 */ {`builtin "string"; strSplit("one-two-three", "-")`, newListA("one", "two", "three"), nil},
+		/*  17 */ {`builtin "string"; strSplit("one-two-three", "-")`, kern.NewListA("one", "two", "three"), nil},
 		/*  18 */ {`builtin "string"; strJoin("-", [1, "two", "three"])`, nil, `strJoin(): expected string, got integer (1)`},
 		/*  19 */ {`builtin "string"; strJoin()`, nil, `strJoin(): too few params -- expected 1 or more, got 0`},
 		/*  20 */ {`builtin "string"; strUpper("StOp")`, "STOP", nil},

t_common_test.go

@@ -9,6 +9,8 @@ import (
 	"reflect"
 	"strings"
 	"testing"
+
+	"git.portale-stac.it/go-pkg/expr/kern"
 )
 
 type inputType struct {
@@ -17,7 +19,7 @@ type inputType struct {
 	wantErr    any
 }
 
-func runCtxTestSuiteSpec(t *testing.T, ctx ExprContext, section string, inputs []inputType, spec ...int) {
+func runCtxTestSuiteSpec(t *testing.T, ctx kern.ExprContext, section string, inputs []inputType, spec ...int) {
 	succeeded := 0
 	failed := 0
 	for _, count := range spec {
@@ -36,7 +38,7 @@ func runTestSuiteSpec(t *testing.T, section string, inputs []inputType, spec ...
 	runCtxTestSuiteSpec(t, nil, section, inputs, spec...)
 }
 
-func runCtxTestSuite(t *testing.T, ctx ExprContext, section string, inputs []inputType) {
+func runCtxTestSuite(t *testing.T, ctx kern.ExprContext, section string, inputs []inputType) {
 
 	succeeded := 0
 	failed := 0
@@ -68,8 +70,8 @@ func getWantedError(input *inputType) error {
 	return wantErr
 }
 
-func doTest(t *testing.T, ctx ExprContext, section string, input *inputType, count int) (good bool) {
-	var expr Expr
+func doTest(t *testing.T, ctx kern.ExprContext, section string, input *inputType, count int) (good bool) {
+	var ast Expr
 	var gotResult any
 	var gotErr error
 	var eq, eqDone bool
@@ -87,13 +89,13 @@ func doTest(t *testing.T, ctx ExprContext, section string, input *inputType, cou
 	scanner := NewScanner(r, DefaultTranslations())
 
 	good = true
-	if expr, gotErr = parser.Parse(scanner); gotErr == nil {
-		gotResult, gotErr = expr.Eval(ctx)
+	if ast, gotErr = parser.Parse(scanner); gotErr == nil {
+		gotResult, gotErr = ast.Eval(ctx)
 	}
 
 	if input.wantResult != nil && gotResult != nil {
-		if ls1, ok := input.wantResult.(*ListType); ok {
-			if ls2, ok := gotResult.(*ListType); ok {
+		if ls1, ok := input.wantResult.(*kern.ListType); ok {
+			if ls2, ok := gotResult.(*kern.ListType); ok {
 				eq = ls1.Equals(*ls2)
 				eqDone = true
 			}
@@ -105,13 +107,13 @@ func doTest(t *testing.T, ctx ExprContext, section string, input *inputType, cou
 	}
 
 	if !eq /*gotResult != input.wantResult*/ {
-		t.Errorf("%d: `%s` -> result = %v [%s], want = %v [%s]", count, input.source, gotResult, TypeName(gotResult), input.wantResult, TypeName(input.wantResult))
+		t.Errorf(">>>%s/%d: `%s` -> result = %v [%s], want = %v [%s]", section, count, input.source, gotResult, kern.TypeName(gotResult), input.wantResult, kern.TypeName(input.wantResult))
 		good = false
 	}
 
 	if gotErr != wantErr {
 		if wantErr == nil || gotErr == nil || (gotErr.Error() != wantErr.Error()) {
-			t.Errorf("%d: %s -> got-err = <%v>, expected-err = <%v>", count, input.source, gotErr, wantErr)
+			t.Errorf(">>>%s/%d: %s -> got-err = <%v>, expected-err = <%v>", section, count, input.source, gotErr, wantErr)
 			good = false
 		}
 	}

t_context_test.go

@@ -0,0 +1,60 @@
+// Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
+// All rights reserved.
+
+// t_context_test.go
+package expr
+
+import (
+	"testing"
+)
+
+func TestCtrlSet(t *testing.T) {
+	section := "Context"
+	varName := "_test_var"
+	varValue := "test-value"
+	prevValue := "test-prev"
+
+	ctx := NewSimpleStore()
+	GlobalCtrlSet(ctx, varName, prevValue)
+	if v := GlobalCtrlSet(ctx, varName, varValue); v != nil {
+		if s, ok := v.(string); ok {
+			if s != prevValue {
+				t.Errorf(`%s -- CtrlSet(%q, %q) should have returned %q, got %q`, section, varName, varValue, varValue, s)
+			}
+		} else {
+			t.Errorf(`%s -- CtrlSet(%q, %q) should have returned a string, got %v [%T]`, section, varName, varValue, v, v)
+		}
+	} else {
+		t.Errorf(`%s -- CtrlSet(%q, %q) should have returned a value, got nil`, section, varName, varValue)
+	}
+}
+
+func TestCtrlGet(t *testing.T) {
+	section := "Context"
+	varName := "_test_var"
+	varValue := "test-value"
+
+	ctx := NewSimpleStore()
+	GlobalCtrlSet(ctx, varName, varValue)
+	if v := GlobalCtrlGet(ctx, varName); v != nil {
+		if s, ok := v.(string); ok {
+			if s != "test-value" {
+				t.Errorf(`%s -- CtrlGet(%q) should have returned %q, got %q`, section, varName, varValue, s)
+			}
+		} else {
+			t.Errorf(`%s -- CtrlGet(%q) should have returned a string, got %v [%T]`, section, varName, v, v)
+		}
+	} else {
+		t.Errorf(`%s -- CtrlGet(%q) should have returned a value, got nil`, section, varName)
+	}
+}
+
+func TestCtrlGetNotDefined(t *testing.T) {
+	section := "Context"
+	varName := "_test_var"
+
+	ctx := NewSimpleStore()
+	if v := GlobalCtrlGet(ctx, varName); v != nil {
+		t.Errorf(`%s -- CtrlGet(%q) should have returned nil, got %v`, section, varName, v)
+	}
+}

t_dict_test.go

@@ -9,6 +9,8 @@ import (
 
 	"strings"
 	"testing"
+
+	"git.portale-stac.it/go-pkg/expr/kern"
 )
 
 func TestDictParser(t *testing.T) {
@@ -37,7 +39,10 @@ func TestDictParser(t *testing.T) {
 			//"b":2,
 			"c":3
 			}`, map[any]any{"a": 1, "c": 3}, nil},
-		}
+		/* 13 */ {`D={"a":1, "b":2}; D."a"`, int64(1), nil},
+		/* 14 */ {`D={"a":1, "b":2}; D.a`, int64(1), nil},
+		/* 15 */ {`D={1:"a", 2:"b", 3:"c"}; D.(1+2)`, "c", nil},
+	}
 
 	succeeded := 0
 	failed := 0
@@ -51,7 +56,7 @@ func TestDictParser(t *testing.T) {
 		var gotResult any
 		var gotErr error
 
-		ctx := NewSimpleStore()
+		ctx := NewSimpleStoreWithoutGlobalContext()
 		ctx.SetVar("var1", int64(123))
 		ctx.SetVar("var2", "abc")
 		ImportMathFuncs(ctx)
@@ -118,11 +123,11 @@ func TestDictToStringMultiLine(t *testing.T) {
 	want := `{
   "first": 1
 }`
-	args := map[any]*term{
+	args := map[any]any{
 		"first": newLiteralTerm(NewValueToken(0, 0, SymInteger, "1", 1)),
 	}
-	dict := newDict(args)
-	got := dict.ToString(MultiLine)
+	dict := kern.NewDict(args)
+	got := dict.ToString(kern.MultiLine)
 	// fmt.Printf("got=%q\n", got)
 
 	if good = got == want; !good {
@@ -140,10 +145,10 @@ func TestDictToString(t *testing.T) {
 	var good bool
 	section := "dict-ToString-SL"
 	want := `{"first": 1}`
-	args := map[any]*term{
+	args := map[any]any{
 		"first": newLiteralTerm(NewValueToken(0, 0, SymInteger, "1", 1)),
 	}
-	dict := newDict(args)
+	dict := kern.NewDict(args)
 	got := dict.ToString(0)
 	// fmt.Printf("got=%q\n", got)
 

t_expr_test.go

@@ -6,6 +6,8 @@ package expr
 
 import (
 	"testing"
+
+	"git.portale-stac.it/go-pkg/expr/kern"
 )
 
 func TestExpr(t *testing.T) {
@@ -29,7 +31,7 @@ func TestExpr(t *testing.T) {
 		/*  15 */ {`a=3; a*=2)+1; a`, nil, `[1:11] unexpected token ")"`},
 		/*  16 */ {`v=[2]; a=1; v[a-=1]=5; v[0]`, int64(5), nil},
 		/*  17 */ {`true ? {"a"} :: {"b"}`, "a", nil},
-		/*  18 */ {`$$`, NewDict(map[any]any{"variables": NewDict(nil), "functions": NewDict(nil)}), nil},
+		/*  18 */ {`$$`, kern.NewDict(map[any]any{"variables": kern.NewDict(nil), "functions": kern.NewDict(nil)}), nil},
 		///*  19 */ {`$$global`, NewDict(map[any]any{"variables": NewDict(nil), "functions": NewDict(nil)}), nil},
 		/*  19 */ {`
 		ds={

t_fractions_test.go

@@ -6,43 +6,45 @@ package expr
 
 import (
 	"testing"
+
+	"git.portale-stac.it/go-pkg/expr/kern"
 )
 
 func TestFractionsParser(t *testing.T) {
 	section := "Fraction"
 	inputs := []inputType{
-		/*   1 */ {`1:2`, newFraction(1, 2), nil},
-		/*   2 */ {`1:2 + 1`, newFraction(3, 2), nil},
-		/*   3 */ {`1:2 - 1`, newFraction(-1, 2), nil},
-		/*   4 */ {`1:2 * 1`, newFraction(1, 2), nil},
-		/*   5 */ {`1:2 * 2:3`, newFraction(2, 6), nil},
-		/*   6 */ {`1:2 / 2:3`, newFraction(3, 4), nil},
+		/*   1 */ {`1:2`, kern.NewFraction(1, 2), nil},
+		/*   2 */ {`1:2 + 1`, kern.NewFraction(3, 2), nil},
+		/*   3 */ {`1:2 - 1`, kern.NewFraction(-1, 2), nil},
+		/*   4 */ {`1:2 * 1`, kern.NewFraction(1, 2), nil},
+		/*   5 */ {`1:2 * 2:3`, kern.NewFraction(2, 6), nil},
+		/*   6 */ {`1:2 / 2:3`, kern.NewFraction(3, 4), nil},
 		/*   7 */ {`1:"5"`, nil, `denominator must be integer, got string (5)`},
 		/*   8 */ {`"1":5`, nil, `numerator must be integer, got string (1)`},
-		/*   9 */ {`1:+5`, newFraction(1, 5), nil},
-		/*  10 */ {`1:(-2)`, newFraction(-1, 2), nil},
-		/*  11 */ {`builtin "math.arith"; add(1:2, 2:3)`, newFraction(7, 6), nil},
+		/*   9 */ {`1:+5`, kern.NewFraction(1, 5), nil},
+		/*  10 */ {`1:(-2)`, kern.NewFraction(-1, 2), nil},
+		/*  11 */ {`builtin "math.arith"; add(1:2, 2:3)`, kern.NewFraction(7, 6), nil},
 		/*  12 */ {`builtin "math.arith"; add(1:2, 1.0, 2)`, float64(3.5), nil},
-		/*  13 */ {`builtin "math.arith"; mul(1:2, 2:3)`, newFraction(2, 6), nil},
+		/*  13 */ {`builtin "math.arith"; mul(1:2, 2:3)`, kern.NewFraction(2, 6), nil},
 		/*  14 */ {`builtin "math.arith"; mul(1:2, 1.0, 2)`, float64(1.0), nil},
 		/*  15 */ {`1:0`, nil, `[1:3] division by zero`},
-		/*  16 */ {`fract(-0.5)`, newFraction(-1, 2), nil},
-		/*  17 */ {`fract("")`, (*FractionType)(nil), `bad syntax`},
-		/*  18 */ {`fract("-1")`, newFraction(-1, 1), nil},
-		/*  19 */ {`fract("+1")`, newFraction(1, 1), nil},
-		/*  20 */ {`fract("1a")`, (*FractionType)(nil), `strconv.ParseInt: parsing "1a": invalid syntax`},
+		/*  16 */ {`fract(-0.5)`, kern.NewFraction(-1, 2), nil},
+		/*  17 */ {`fract("")`, (*kern.FractionType)(nil), `bad syntax`},
+		/*  18 */ {`fract("-1")`, kern.NewFraction(-1, 1), nil},
+		/*  19 */ {`fract("+1")`, kern.NewFraction(1, 1), nil},
+		/*  20 */ {`fract("1a")`, (*kern.FractionType)(nil), `strconv.ParseInt: parsing "1a": invalid syntax`},
 		/*  21 */ {`fract(1,0)`, nil, `fract(): division by zero`},
 		/*  22 */ {`string(1:2)`, "1:2", nil},
 		/*  23 */ {`1+1:2+0.5`, float64(2), nil},
 		/*  24 */ {`1:(2-2)`, nil, `[1:3] division by zero`},
-		/*  25 */ {`[0,1][1-1]:1`, newFraction(0, 1), nil},
+		/*  25 */ {`[0,1][1-1]:1`, kern.NewFraction(0, 1), nil},
 	}
 	// runTestSuiteSpec(t, section, inputs, 25)
 	runTestSuite(t, section, inputs)
 }
 
 func TestFractionToStringSimple(t *testing.T) {
-	source := newFraction(1, 2)
+	source := kern.NewFraction(1, 2)
 	want := "1:2"
 	got := source.ToString(0)
 	if got != want {
@@ -51,18 +53,18 @@ func TestFractionToStringSimple(t *testing.T) {
 }
 
 func TestFractionToStringMultiline(t *testing.T) {
-	source := newFraction(1, 2)
+	source := kern.NewFraction(1, 2)
 	want := "1\n-\n2"
-	got := source.ToString(MultiLine)
+	got := source.ToString(kern.MultiLine)
 	if got != want {
 		t.Errorf(`(1,2) -> result = %v [%T], want = %v [%T]`, got, got, want, want)
 	}
 }
 
 func TestToStringMultilineTty(t *testing.T) {
-	source := newFraction(-1, 2)
+	source := kern.NewFraction(-1, 2)
 	want := "\x1b[4m-1\x1b[0m\n 2"
-	got := source.ToString(MultiLine | TTY)
+	got := source.ToString(kern.MultiLine | kern.TTY)
 	if got != want {
 		t.Errorf(`(1,2) -> result = %#v [%T], want = %#v [%T]`, got, got, want, want)
 	}

t_funcs_test.go

@@ -6,6 +6,8 @@ package expr
 
 import (
 	"testing"
+
+	"git.portale-stac.it/go-pkg/expr/kern"
 )
 
 func TestFuncs(t *testing.T) {
@@ -47,12 +49,12 @@ func TestFuncs(t *testing.T) {
 	runTestSuite(t, section, inputs)
 }
 
-func dummy(ctx ExprContext, name string, args map[string]any) (result any, err error) {
+func dummy(ctx kern.ExprContext, name string, args map[string]any) (result any, err error) {
 	return
 }
 
 func TestFunctionToStringSimple(t *testing.T) {
-	source := NewGolangFunctor(dummy)
+	source := kern.NewGolangFunctor(dummy)
 	want := "func(){}"
 	got := source.ToString(0)
 	if got != want {
@@ -61,8 +63,8 @@ func TestFunctionToStringSimple(t *testing.T) {
 }
 
 func TestFunctionGetFunc(t *testing.T) {
-	source := NewGolangFunctor(dummy)
-	want := ExprFunc(nil)
+	source := kern.NewGolangFunctor(dummy)
+	want := kern.ExprFunc(nil)
 	got := source.GetFunc()
 	if got != want {
 		t.Errorf(`(func() -> result = %v [%T], want = %v [%T]`, got, got, want, want)
@@ -76,16 +78,16 @@ func TestGoFunction(t *testing.T) {
 		/*   2 */ {`myName("Peppino")`, "Peppino", nil},
 	}
 
-	myName := func(ctx ExprContext, name string, args map[string]any) (result any, err error) {
+	myName := func(ctx kern.ExprContext, name string, args map[string]any) (result any, err error) {
 		var ok bool
 		if result, ok = args["name"].(string); !ok {
-			err = ErrWrongParamType(name, "name", TypeString, args["name"])
+			err = kern.ErrWrongParamType(name, "name", kern.TypeString, args["name"])
 		}
 		return
 	}
 
-	ctx := NewSimpleStore()
-	ctx.RegisterFunc("myName", NewGolangFunctor(myName), TypeString, []ExprFuncParam{
+	ctx := NewSimpleStoreWithoutGlobalContext()
+	ctx.RegisterFunc("myName", kern.NewGolangFunctor(myName), kern.TypeString, []kern.ExprFuncParam{
 		NewFuncParamFlagDef("name", PfOptional|PfDefault, "Celestino Amoroso"),
 	})
 

t_helpers_test.go

@@ -53,7 +53,7 @@ import (
 
 func TestEvalString(t *testing.T) {
 
-	ctx := NewSimpleStore()
+	ctx := NewSimpleStoreWithoutGlobalContext()
 	ctx.SetVar("a", uint8(1))
 	ctx.SetVar("b", int8(2))
 	ctx.SetVar("f", 2.0)

t_iter-list_test.go

@@ -7,10 +7,12 @@ package expr
 import (
 	"io"
 	"testing"
+
+	"git.portale-stac.it/go-pkg/expr/kern"
 )
 
 func TestNewListIterator(t *testing.T) {
-	list := newListA("a", "b", "c", "d")
+	list := kern.NewListA("a", "b", "c", "d")
 	it := NewListIterator(list, []any{1, 3, 1})
 	if item, err := it.Next(); err != nil {
 		t.Errorf("error: %v", err)
@@ -22,7 +24,7 @@ func TestNewListIterator(t *testing.T) {
 }
 
 func TestNewListIterator2(t *testing.T) {
-	list := newListA("a", "b", "c", "d")
+	list := kern.NewListA("a", "b", "c", "d")
 	it := NewListIterator(list, []any{3, 1, -1})
 	if item, err := it.Next(); err != nil {
 		t.Errorf("error: %v", err)
@@ -34,7 +36,7 @@ func TestNewListIterator2(t *testing.T) {
 }
 
 func TestNewListIterator3(t *testing.T) {
-	list := newListA("a", "b", "c", "d")
+	list := kern.NewListA("a", "b", "c", "d")
 	it := NewListIterator(list, []any{1, -1, 1})
 	if item, err := it.Next(); err != nil {
 		t.Errorf("error: %v", err)
@@ -90,7 +92,7 @@ func TestNewIterList5(t *testing.T) {
 }
 
 func TestNewIterList6(t *testing.T) {
-	list := newListA("a", "b", "c", "d")
+	list := kern.NewListA("a", "b", "c", "d")
 	it1, _ := NewIterator(list)
 	it, _ := NewIterator(it1)
 	if item, err := it.Next(); err != nil {
@@ -101,6 +103,7 @@ func TestNewIterList6(t *testing.T) {
 		t.Logf("Next: %v", item)
 	}
 }
+
 func TestNewString(t *testing.T) {
 	list := "123"
 	it, _ := NewIterator(list)
@@ -111,7 +114,7 @@ func TestNewString(t *testing.T) {
 
 func TestHasOperation(t *testing.T) {
 
-	list := newListA("a", "b", "c", "d")
+	list := kern.NewListA("a", "b", "c", "d")
 	it := NewListIterator(list, []any{1, 3, 1})
 	hasOp := it.HasOperation("reset")
 	if !hasOp {
@@ -121,7 +124,7 @@ func TestHasOperation(t *testing.T) {
 
 func TestCallOperationReset(t *testing.T) {
 
-	list := newListA("a", "b", "c", "d")
+	list := kern.NewListA("a", "b", "c", "d")
 	it := NewListIterator(list, []any{1, 3, 1})
 	if v, err := it.CallOperation("reset", nil); err != nil {
 		t.Errorf("Error on CallOperation(reset): %v", err)
@@ -132,7 +135,7 @@ func TestCallOperationReset(t *testing.T) {
 
 func TestCallOperationIndex(t *testing.T) {
 
-	list := newListA("a", "b", "c", "d")
+	list := kern.NewListA("a", "b", "c", "d")
 	it := NewListIterator(list, []any{1, 3, 1})
 	if v, err := it.CallOperation("index", nil); err != nil {
 		t.Errorf("Error on CallOperation(index): %v", err)
@@ -143,7 +146,7 @@ func TestCallOperationIndex(t *testing.T) {
 
 func TestCallOperationCount(t *testing.T) {
 
-	list := newListA("a", "b", "c", "d")
+	list := kern.NewListA("a", "b", "c", "d")
 	it := NewListIterator(list, []any{1, 3, 1})
 	if v, err := it.CallOperation("count", nil); err != nil {
 		t.Errorf("Error on CallOperation(count): %v", err)
@@ -154,7 +157,7 @@ func TestCallOperationCount(t *testing.T) {
 
 func TestCallOperationUnknown(t *testing.T) {
 
-	list := newListA("a", "b", "c", "d")
+	list := kern.NewListA("a", "b", "c", "d")
 	it := NewListIterator(list, []any{1, 3, 1})
 	if v, err := it.CallOperation("unknown", nil); err == nil {
 		t.Errorf("Expected error on CallOperation(unknown), got %v", v)