new iter-iter iterator and kern.func-info module

builtin-base.go

@@ -272,7 +272,7 @@ func setFunc(ctx kern.ExprContext, name string, args map[string]any) (result any
 
 func ImportBuiltinsFuncs(ctx kern.ExprContext) {
 	anyParams := []kern.ExprFuncParam{
-		NewFuncParam(kern.ParamValue),
+		kern.NewFuncParam(kern.ParamValue),
 	}
 
 	ctx.RegisterFunc("isNil", kern.NewGolangFunctor(isNilFunc), kern.TypeBoolean, anyParams)
@@ -290,27 +290,27 @@ func ImportBuiltinsFuncs(ctx kern.ExprContext) {
 	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),
+		kern.NewFuncParam(kern.ParamValue),
-		NewFuncParamFlagDef(ParamDenominator, PfDefault, int64(1)),
+		kern.NewFuncParamFlagDef(ParamDenominator, kern.PfDefault, int64(1)),
 	})
 
 	ctx.RegisterFunc("eval", kern.NewGolangFunctor(evalFunc), kern.TypeAny, []kern.ExprFuncParam{
-		NewFuncParam(kern.ParamSource),
+		kern.NewFuncParam(kern.ParamSource),
 	})
 
 	ctx.RegisterFunc("var", kern.NewGolangFunctor(varFunc), kern.TypeAny, []kern.ExprFuncParam{
-		NewFuncParam(kern.ParamName),
+		kern.NewFuncParam(kern.ParamName),
-		NewFuncParamFlagDef(kern.ParamValue, PfDefault, nil),
+		kern.NewFuncParamFlagDef(kern.ParamValue, kern.PfDefault, nil),
 	})
 
 	ctx.RegisterFunc("set", kern.NewGolangFunctor(setFunc), kern.TypeAny, []kern.ExprFuncParam{
-		NewFuncParam(kern.ParamName),
+		kern.NewFuncParam(kern.ParamName),
-		NewFuncParam(kern.ParamValue),
+		kern.NewFuncParam(kern.ParamValue),
 	})
 
 	// ctx.RegisterFunc("unset", kern.NewGolangFunctor(unsetFunc), kern.TypeAny, []kern.ExprFuncParam{
-	// 	NewFuncParam(kern.ParamName),
+	// 	kern.NewFuncParam(kern.ParamName),
-	// 	NewFuncParam(kern.ParamValue),
+	// 	kern.NewFuncParam(kern.ParamValue),
 	// })
 }
 

builtin-fmt.go

@@ -47,10 +47,10 @@ func printLnFunc(ctx kern.ExprContext, name string, args map[string]any) (result
 
 func ImportFmtFuncs(ctx kern.ExprContext) {
 	ctx.RegisterFunc("print", kern.NewGolangFunctor(printFunc), kern.TypeInt, []kern.ExprFuncParam{
-		NewFuncParamFlag(kern.ParamItem, PfRepeat),
+		kern.NewFuncParamFlag(kern.ParamItem, kern.PfRepeat),
 	})
 	ctx.RegisterFunc("println", kern.NewGolangFunctor(printLnFunc), kern.TypeInt, []kern.ExprFuncParam{
-		NewFuncParamFlag(kern.ParamItem, PfRepeat),
+		kern.NewFuncParamFlag(kern.ParamItem, kern.PfRepeat),
 	})
 }
 

builtin-import.go

@@ -69,10 +69,10 @@ func doImport(ctx kern.ExprContext, name string, dirList []string, it kern.Itera
 
 func ImportImportFuncs(ctx kern.ExprContext) {
 	ctx.RegisterFunc("import", kern.NewGolangFunctor(importFunc), kern.TypeAny, []kern.ExprFuncParam{
-		NewFuncParamFlag(kern.ParamFilepath, PfRepeat),
+		kern.NewFuncParamFlag(kern.ParamFilepath, kern.PfRepeat),
 	})
 	ctx.RegisterFunc("importAll", kern.NewGolangFunctor(importAllFunc), kern.TypeAny, []kern.ExprFuncParam{
-		NewFuncParamFlag(kern.ParamFilepath, PfRepeat),
+		kern.NewFuncParamFlag(kern.ParamFilepath, kern.PfRepeat),
 	})
 }
 

builtin-iterator.go

@@ -94,9 +94,9 @@ func runFunc(ctx kern.ExprContext, name string, args map[string]any) (result any
 
 func ImportIterFuncs(ctx kern.ExprContext) {
 	ctx.RegisterFunc("run", kern.NewGolangFunctor(runFunc), kern.TypeAny, []kern.ExprFuncParam{
-		NewFuncParam(kern.ParamIterator),
+		kern.NewFuncParam(kern.ParamIterator),
-		NewFuncParamFlag(iterParamOperator, PfOptional),
+		kern.NewFuncParamFlag(iterParamOperator, kern.PfOptional),
-		NewFuncParamFlag(iterParamVars, PfOptional),
+		kern.NewFuncParamFlag(iterParamVars, kern.PfOptional),
 	})
 }
 

builtin-math-arith.go

@@ -172,11 +172,11 @@ func mulFunc(ctx kern.ExprContext, name string, args map[string]any) (result any
 
 func ImportMathFuncs(ctx kern.ExprContext) {
 	ctx.RegisterFunc("add", kern.NewGolangFunctor(addFunc), kern.TypeNumber, []kern.ExprFuncParam{
-		NewFuncParamFlagDef(kern.ParamValue, PfDefault|PfRepeat, int64(0)),
+		kern.NewFuncParamFlagDef(kern.ParamValue, kern.PfDefault|kern.PfRepeat, int64(0)),
 	})
 
 	ctx.RegisterFunc("mul", kern.NewGolangFunctor(mulFunc), kern.TypeNumber, []kern.ExprFuncParam{
-		NewFuncParamFlagDef(kern.ParamValue, PfDefault|PfRepeat, int64(1)),
+		kern.NewFuncParamFlagDef(kern.ParamValue, kern.PfDefault|kern.PfRepeat, int64(1)),
 	})
 }
 

builtin-os-file.go

@@ -224,37 +224,37 @@ func fileReadTextAllFunc(ctx kern.ExprContext, name string, args map[string]any)
 
 func ImportOsFuncs(ctx kern.ExprContext) {
 	ctx.RegisterFunc("fileOpen", kern.NewGolangFunctor(openFileFunc), kern.TypeFileHandle, []kern.ExprFuncParam{
-		NewFuncParam(kern.ParamFilepath),
+		kern.NewFuncParam(kern.ParamFilepath),
 	})
 
 	ctx.RegisterFunc("fileAppend", kern.NewGolangFunctor(appendFileFunc), kern.TypeFileHandle, []kern.ExprFuncParam{
-		NewFuncParam(kern.ParamFilepath),
+		kern.NewFuncParam(kern.ParamFilepath),
 	})
 
 	ctx.RegisterFunc("fileCreate", kern.NewGolangFunctor(createFileFunc), kern.TypeFileHandle, []kern.ExprFuncParam{
-		NewFuncParam(kern.ParamFilepath),
+		kern.NewFuncParam(kern.ParamFilepath),
 	})
 
 	ctx.RegisterFunc("fileClose", kern.NewGolangFunctor(closeFileFunc), kern.TypeBoolean, []kern.ExprFuncParam{
-		NewFuncParam(kern.ParamHandle),
+		kern.NewFuncParam(kern.ParamHandle),
 	})
 
 	ctx.RegisterFunc("fileWriteText", kern.NewGolangFunctor(fileWriteTextFunc), kern.TypeInt, []kern.ExprFuncParam{
-		NewFuncParam(kern.ParamHandle),
+		kern.NewFuncParam(kern.ParamHandle),
-		NewFuncParamFlagDef(kern.ParamItem, PfDefault|PfRepeat, ""),
+		kern.NewFuncParamFlagDef(kern.ParamItem, kern.PfDefault|kern.PfRepeat, ""),
 	})
 
 	ctx.RegisterFunc("fileReadText", kern.NewGolangFunctor(fileReadTextFunc), kern.TypeString, []kern.ExprFuncParam{
-		NewFuncParam(kern.ParamHandle),
+		kern.NewFuncParam(kern.ParamHandle),
-		NewFuncParamFlagDef(osLimitCh, PfDefault, "\n"),
+		kern.NewFuncParamFlagDef(osLimitCh, kern.PfDefault, "\n"),
 	})
 
 	ctx.RegisterFunc("fileReadTextAll", kern.NewGolangFunctor(fileReadTextAllFunc), kern.TypeString, []kern.ExprFuncParam{
-		NewFuncParam(kern.ParamHandle),
+		kern.NewFuncParam(kern.ParamHandle),
 	})
 
 	ctx.RegisterFunc("fileReadIterator", kern.NewGolangFunctor(fileReadIteratorFunc), kern.TypeIterator, []kern.ExprFuncParam{
-		NewFuncParam(paramHandleOrPath),
+		kern.NewFuncParam(paramHandleOrPath),
 	})
 }
 

builtin-string.go

@@ -225,44 +225,44 @@ func lowerStrFunc(ctx kern.ExprContext, name string, args map[string]any) (resul
 // Import above functions in the context
 func ImportStringFuncs(ctx kern.ExprContext) {
 	ctx.RegisterFunc("strJoin", kern.NewGolangFunctor(joinStrFunc), kern.TypeString, []kern.ExprFuncParam{
-		NewFuncParam(kern.ParamSeparator),
+		kern.NewFuncParam(kern.ParamSeparator),
-		NewFuncParamFlag(kern.ParamItem, PfRepeat),
+		kern.NewFuncParamFlag(kern.ParamItem, kern.PfRepeat),
 	})
 
 	ctx.RegisterFunc("strSub", kern.NewGolangFunctor(subStrFunc), kern.TypeString, []kern.ExprFuncParam{
-		NewFuncParam(kern.ParamSource),
+		kern.NewFuncParam(kern.ParamSource),
-		NewFuncParamFlagDef(kern.ParamStart, PfDefault, int64(0)),
+		kern.NewFuncParamFlagDef(kern.ParamStart, kern.PfDefault, int64(0)),
-		NewFuncParamFlagDef(kern.ParamCount, PfDefault, int64(-1)),
+		kern.NewFuncParamFlagDef(kern.ParamCount, kern.PfDefault, int64(-1)),
 	})
 
 	ctx.RegisterFunc("strSplit", kern.NewGolangFunctor(splitStrFunc), "list of "+kern.TypeString, []kern.ExprFuncParam{
-		NewFuncParam(kern.ParamSource),
+		kern.NewFuncParam(kern.ParamSource),
-		NewFuncParamFlagDef(kern.ParamSeparator, PfDefault, ""),
+		kern.NewFuncParamFlagDef(kern.ParamSeparator, kern.PfDefault, ""),
-		NewFuncParamFlagDef(kern.ParamCount, PfDefault, int64(-1)),
+		kern.NewFuncParamFlagDef(kern.ParamCount, kern.PfDefault, int64(-1)),
 	})
 
 	ctx.RegisterFunc("strTrim", kern.NewGolangFunctor(trimStrFunc), kern.TypeString, []kern.ExprFuncParam{
-		NewFuncParam(kern.ParamSource),
+		kern.NewFuncParam(kern.ParamSource),
 	})
 
 	ctx.RegisterFunc("strStartsWith", kern.NewGolangFunctor(startsWithStrFunc), kern.TypeBoolean, []kern.ExprFuncParam{
-		NewFuncParam(kern.ParamSource),
+		kern.NewFuncParam(kern.ParamSource),
-		NewFuncParam(kern.ParamPrefix),
+		kern.NewFuncParam(kern.ParamPrefix),
-		NewFuncParamFlag(strParamOther, PfRepeat),
+		kern.NewFuncParamFlag(strParamOther, kern.PfRepeat),
 	})
 
 	ctx.RegisterFunc("strEndsWith", kern.NewGolangFunctor(endsWithStrFunc), kern.TypeBoolean, []kern.ExprFuncParam{
-		NewFuncParam(kern.ParamSource),
+		kern.NewFuncParam(kern.ParamSource),
-		NewFuncParam(kern.ParamSuffix),
+		kern.NewFuncParam(kern.ParamSuffix),
-		NewFuncParamFlag(strParamOther, PfRepeat),
+		kern.NewFuncParamFlag(strParamOther, kern.PfRepeat),
 	})
 
 	ctx.RegisterFunc("strUpper", kern.NewGolangFunctor(upperStrFunc), kern.TypeString, []kern.ExprFuncParam{
-		NewFuncParam(kern.ParamSource),
+		kern.NewFuncParam(kern.ParamSource),
 	})
 
 	ctx.RegisterFunc("strLower", kern.NewGolangFunctor(lowerStrFunc), kern.TypeString, []kern.ExprFuncParam{
-		NewFuncParam(kern.ParamSource),
+		kern.NewFuncParam(kern.ParamSource),
 	})
 }
 

dict-iterator.go

@@ -116,8 +116,11 @@ func NewDictIterator(dict *kern.DictType, args []any) (it *DictIterator, err err
 		}
 	}
 
-	dictIt.makeKeys(*dict, sortType)
+	if err == nil {
-	return dictIt, err
+		dictIt.makeKeys(*dict, sortType)
+		it = dictIt
+	}
+	return
 }
 
 func NewMapIterator(m map[any]any) (it *DictIterator) {
@@ -139,7 +142,6 @@ 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{kern.NextName, kern.ResetName, kern.IndexName, kern.CountName, kern.CurrentName, kern.CleanName, kern.KeyName, kern.ValueName}, name)
 	return yes
 }

function.go

@@ -1,388 +0,0 @@
-// Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
-// All rights reserved.
-
-// function.go
-package expr
-
-import (
-	"fmt"
-	"strings"
-
-	"git.portale-stac.it/go-pkg/expr/kern"
-	"git.portale-stac.it/go-pkg/expr/scan"
-)
-
-// ---- Function template
-// type FuncTemplate func(ctx expr.ExprContext, name string, args map[string]any) (result any, err error)
-
-// ---- Common functor definition
-type BaseFunctor struct {
-	info kern.ExprFunc
-}
-
-func (functor *BaseFunctor) ToString(opt kern.FmtOpt) (s string) {
-	if functor.info != nil {
-		s = functor.info.ToString(opt)
-	} else {
-		s = "func(){}"
-	}
-	return s
-}
-
-func (functor *BaseFunctor) GetParams() (params []kern.ExprFuncParam) {
-	if functor.info != nil {
-		return functor.info.Params()
-	} else {
-		return []kern.ExprFuncParam{}
-	}
-}
-
-func (functor *BaseFunctor) SetFunc(info kern.ExprFunc) {
-	functor.info = info
-}
-
-func (functor *BaseFunctor) GetFunc() kern.ExprFunc {
-	return functor.info
-}
-
-func (functor *BaseFunctor) GetDefinitionContext() kern.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) kern.ExprFuncParam {
-	return &funcParamInfo{name: name}
-}
-
-func NewFuncParamFlag(name string, flags paramFlags) kern.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 kern.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
-}
-
-// --- Functions
-
-// funcInfo implements expr.ExprFunc
-type funcInfo struct {
-	name         string
-	minArgs      int
-	maxArgs      int
-	functor      kern.Functor
-	formalParams []kern.ExprFuncParam
-	returnType   string
-}
-
-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 {
-		if maxArgs == -1 {
-			return nil, fmt.Errorf("no more params can be specified after the ellipsis symbol: %q", p.Name())
-		}
-		if p.IsDefault() || p.IsOptional() {
-			maxArgs++
-		} else if maxArgs == minArgs {
-			minArgs++
-			maxArgs++
-		} else {
-			return nil, fmt.Errorf("can't specify non-optional param after optional ones: %q", p.Name())
-		}
-		if p.IsRepeat() {
-			minArgs--
-			maxArgs = -1
-		}
-	}
-
-	info = &funcInfo{
-		name: name, minArgs: minArgs, maxArgs: maxArgs, functor: functor, returnType: returnType, formalParams: params,
-	}
-	functor.SetFunc(info)
-	return info, nil
-}
-
-func (info *funcInfo) Params() []kern.ExprFuncParam {
-	return info.formalParams
-}
-
-func (info *funcInfo) ReturnType() string {
-	return info.returnType
-}
-
-func (info *funcInfo) ToString(opt kern.FmtOpt) string {
-	var sb strings.Builder
-	if len(info.Name()) == 0 {
-		sb.WriteString("func")
-	} else {
-		sb.WriteString(info.Name())
-	}
-	sb.WriteByte('(')
-	if info.formalParams != nil {
-		for i, p := range info.formalParams {
-			if i > 0 {
-				sb.WriteString(", ")
-			}
-			sb.WriteString(p.Name())
-
-			if p.IsDefault() {
-				sb.WriteByte('=')
-				if s, ok := p.DefaultValue().(string); ok {
-					sb.WriteByte('"')
-					sb.WriteString(s)
-					sb.WriteByte('"')
-				} else {
-					sb.WriteString(fmt.Sprintf("%v", p.DefaultValue()))
-				}
-			}
-		}
-	}
-	if info.maxArgs < 0 {
-		sb.WriteString(" ...")
-	}
-	sb.WriteString("):")
-	if len(info.returnType) > 0 {
-		sb.WriteString(info.returnType)
-	} else {
-		sb.WriteString(kern.TypeAny)
-	}
-	sb.WriteString("{}")
-	return sb.String()
-}
-
-func (info *funcInfo) Name() string {
-	return info.name
-}
-
-func (info *funcInfo) MinArgs() int {
-	return info.minArgs
-}
-
-func (info *funcInfo) MaxArgs() int {
-	return info.maxArgs
-}
-
-func (info *funcInfo) Functor() kern.Functor {
-	return info.functor
-}
-
-func (info *funcInfo) AllocContext(parentCtx kern.ExprContext) (ctx kern.ExprContext) {
-	if defCtx := info.functor.GetDefinitionContext(); defCtx != nil {
-		ctx = defCtx.Clone()
-		ctx.SetParent(defCtx)
-	} else {
-		ctx = parentCtx.Clone()
-		ctx.SetParent(parentCtx)
-	}
-	return
-}
-
-func (info *funcInfo) ParamSpec(paramName string) kern.ExprFuncParam {
-	for _, spec := range info.formalParams {
-		if spec.Name() == paramName {
-			return spec
-		}
-	}
-	return nil
-}
-
-func initActualParams(ctx kern.ExprContext, info kern.ExprFunc, callTerm *scan.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
-	}
-
-	for i, tree := range callTerm.Children {
-		var paramValue any
-		paramCtx := ctx.Clone()
-		if paramValue, err = tree.Compute(paramCtx); err != nil {
-			break
-		}
-		if paramName, namedParam := kern.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, len(callTerm.Children)-i)
-					varArgs = append(varArgs, paramValue)
-					varName = spec.Name()
-				} else {
-					actualParams[spec.Name()] = paramValue
-				}
-			} else {
-				err = kern.ErrTooManyParams(info.Name(), len(formalParams), len(callTerm.Children))
-				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 = kern.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 = 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 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 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 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 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
-// }

helpers.go

@@ -45,7 +45,7 @@ func EvalStringV(source string, args []Arg) (result any, err error) {
 				functor := kern.NewGolangFunctor(f)
 				// ctx.RegisterFunc(arg.Name, functor, 0, -1)
 				ctx.RegisterFunc(arg.Name, functor, kern.TypeAny, []kern.ExprFuncParam{
-					NewFuncParamFlagDef(kern.ParamValue, PfDefault|PfRepeat, 0),
+					kern.NewFuncParamFlagDef(kern.ParamValue, kern.PfDefault|kern.PfRepeat, 0),
 				})
 			} else {
 				err = fmt.Errorf("invalid function specification: %q", arg.Name)

iter-factory.go

@@ -5,10 +5,13 @@
 package expr
 
 import (
+	"fmt"
+	"slices"
+
 	"git.portale-stac.it/go-pkg/expr/kern"
 )
 
-func NewIterator(value any) (it kern.Iterator, err error) {
+func NewIterator(ctx kern.ExprContext, value any, args map[string]any) (it kern.Iterator, err error) {
 	if value == nil {
 		return NewArrayIterator([]any{}), nil
 	}
@@ -21,9 +24,24 @@ func NewIterator(value any) (it kern.Iterator, err error) {
 	case []any:
 		it = NewArrayIterator(v)
 	case kern.Iterator:
-		it = v
+		// it = v
+		var op kern.Functor
+		if len(args) >= 1 {
+			if opArg, ok := args["op"]; ok {
+				if op, ok = opArg.(kern.Functor); !ok {
+					err = fmt.Errorf("the 'op' argument must be a kern.Functor, got %T", opArg)
+				}
+			}
+		}
+		if err == nil {
+			it, err = NewIterIter(v, ctx, op, args)
+		}
 	default:
 		it = NewArrayIterator([]any{value})
 	}
 	return
 }
+
+func HasStandardOperation(name string) bool {
+	return slices.Contains([]string{kern.NextName, kern.ResetName, kern.IndexName, kern.CountName, kern.CurrentName, kern.CleanName}, name)
+}

iter-iter.go

@@ -0,0 +1,132 @@
+// Copyright (c) 2024-2026 Celestino Amoroso (celestino.amoroso@gmail.com).
+// All rights reserved.
+
+// iter-iter.go
+package expr
+
+import (
+	"fmt"
+	"io"
+
+	"git.portale-stac.it/go-pkg/expr/kern"
+)
+
+type IterIter struct {
+	it      kern.Iterator
+	count   int64
+	index   int64
+	ctx     kern.ExprContext
+	op      kern.Functor
+	opName  string
+	args    map[string]any
+	current any
+}
+
+func NewIterIter(it kern.Iterator, ctx kern.ExprContext, op kern.Functor, args map[string]any) (iter kern.Iterator, err error) {
+	var opName string
+	if op != nil {
+		if f := op.GetFunc(); f != nil {
+			opName = f.Name()
+			// } else {
+			// 	return nil, fmt.Errorf("invalid functor argument for iter-iter: expected kern.Functor, got %T", args["op"])
+		}
+	}
+	if len(opName) == 0 {
+		opName = "anonymous"
+	}
+	iter = &IterIter{it: it, count: 0, index: -1, ctx: ctx, op: op, opName: opName, args: args}
+
+	return
+}
+
+func (it *IterIter) String() string {
+	return fmt.Sprintf("$(%s)", it.it)
+}
+
+func (it *IterIter) TypeName() string {
+	return "IterIter"
+}
+
+func (it *IterIter) HasOperation(name string) bool {
+	return HasStandardOperation(name)
+}
+
+func (it *IterIter) 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 *IterIter) Current() (item any, err error) {
+	if it.current != nil {
+		item = it.current
+	} else if it.op != nil {
+		if item, err = it.op.InvokeNamed(it.ctx, it.opName, it.args); err == nil {
+			it.current = item
+		}
+	} else {
+		var exists bool
+		if it.current, exists = it.ctx.GetVar("_"); !exists {
+			err = fmt.Errorf("current item not available")
+		} else {
+			item = it.current
+		}
+	}
+	return
+}
+
+func (it *IterIter) Next() (item any, err error) {
+	var src any
+
+	it.current = nil
+	ctx := it.ctx
+	for src, err = it.it.Next(); src == nil && err == nil; src, err = it.it.Next() {
+	}
+
+	if err == nil {
+		if src == nil {
+			err = io.EOF
+		} else {
+			ctx.UnsafeSetVar("_", src)
+			ctx.UnsafeSetVar("__", it.it.Index())
+			ctx.UnsafeSetVar("_#", it.it.Count())
+			item, err = it.Current()
+			ctx.DeleteVar("_#")
+			ctx.DeleteVar("__")
+			ctx.DeleteVar("_")
+		}
+	}
+	return
+}
+
+func (it *IterIter) Index() int64 {
+	return it.index
+}
+
+func (it *IterIter) Count() int64 {
+	return it.count
+}
+
+func (it *IterIter) Reset() error {
+	it.index = -1
+	it.count = 0
+	return nil
+}
+
+func (it *IterIter) Clean() error {
+	return nil
+}

kern/bind-go-functions.go

@@ -5,19 +5,19 @@
 package kern
 
 // ---- Linking with Go functions
-type golangFunctor struct {
+type GolangFunctor struct {
 	BaseFunctor
 	f FuncTemplate
 }
 
-func NewGolangFunctor(f FuncTemplate) *golangFunctor {
+func NewGolangFunctor(f FuncTemplate) *GolangFunctor {
-	return &golangFunctor{f: f}
+	return &GolangFunctor{f: f}
 }
 
-func (functor *golangFunctor) TypeName() string {
+func (functor *GolangFunctor) TypeName() string {
 	return "GoFunctor"
 }
 
-func (functor *golangFunctor) InvokeNamed(ctx ExprContext, name string, args map[string]any) (result any, err error) {
+func (functor *GolangFunctor) InvokeNamed(ctx ExprContext, name string, args map[string]any) (result any, err error) {
 	return functor.f(ctx, name, args)
 }

kern/expr-function.go

@@ -37,3 +37,8 @@ type ExprFunc interface {
 	PrepareCall(name string, actualParams map[string]any) (err error)
 	AllocContext(parentCtx ExprContext) (ctx ExprContext)
 }
+
+func IsFunctor(v any) (ok bool) {
+	_, ok = v.(Functor)
+	return
+}

kern/func-info.go

@@ -0,0 +1,164 @@
+// Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
+// All rights reserved.
+
+// func-info.go
+package kern
+
+import (
+	"fmt"
+	"strings"
+)
+
+// --- Functions
+
+// FuncInfo implements expr.ExprFunc
+type FuncInfo struct {
+	name         string
+	minArgs      int
+	maxArgs      int
+	functor      Functor
+	formalParams []ExprFuncParam
+	returnType   string
+}
+
+func NewFuncInfo(name string, functor Functor, returnType string, params []ExprFuncParam) (info *FuncInfo, err error) {
+	var minArgs = 0
+	var maxArgs = 0
+	for _, p := range params {
+		if maxArgs == -1 {
+			return nil, fmt.Errorf("no more params can be specified after the ellipsis symbol: %q", p.Name())
+		}
+		if p.IsDefault() || p.IsOptional() {
+			maxArgs++
+		} else if maxArgs == minArgs {
+			minArgs++
+			maxArgs++
+		} else {
+			return nil, fmt.Errorf("can't specify non-optional param after optional ones: %q", p.Name())
+		}
+		if p.IsRepeat() {
+			minArgs--
+			maxArgs = -1
+		}
+	}
+
+	info = &FuncInfo{
+		name: name, minArgs: minArgs, maxArgs: maxArgs, functor: functor, returnType: returnType, formalParams: params,
+	}
+	functor.SetFunc(info)
+	return info, nil
+}
+
+func (info *FuncInfo) Params() []ExprFuncParam {
+	return info.formalParams
+}
+
+func (info *FuncInfo) ReturnType() string {
+	return info.returnType
+}
+
+func (info *FuncInfo) ToString(opt FmtOpt) string {
+	var sb strings.Builder
+	if len(info.Name()) == 0 {
+		sb.WriteString("func")
+	} else {
+		sb.WriteString(info.Name())
+	}
+	sb.WriteByte('(')
+	if info.formalParams != nil {
+		for i, p := range info.formalParams {
+			if i > 0 {
+				sb.WriteString(", ")
+			}
+			sb.WriteString(p.Name())
+
+			if p.IsDefault() {
+				sb.WriteByte('=')
+				if s, ok := p.DefaultValue().(string); ok {
+					sb.WriteByte('"')
+					sb.WriteString(s)
+					sb.WriteByte('"')
+				} else {
+					sb.WriteString(fmt.Sprintf("%v", p.DefaultValue()))
+				}
+			}
+		}
+	}
+	if info.maxArgs < 0 {
+		sb.WriteString(" ...")
+	}
+	sb.WriteString("):")
+	if len(info.returnType) > 0 {
+		sb.WriteString(info.returnType)
+	} else {
+		sb.WriteString(TypeAny)
+	}
+	sb.WriteString("{}")
+	return sb.String()
+}
+
+func (info *FuncInfo) Name() string {
+	return info.name
+}
+
+func (info *FuncInfo) MinArgs() int {
+	return info.minArgs
+}
+
+func (info *FuncInfo) MaxArgs() int {
+	return info.maxArgs
+}
+
+func (info *FuncInfo) Functor() Functor {
+	return info.functor
+}
+
+func (info *FuncInfo) AllocContext(parentCtx ExprContext) (ctx ExprContext) {
+	if defCtx := info.functor.GetDefinitionContext(); defCtx != nil {
+		ctx = defCtx.Clone()
+		ctx.SetParent(defCtx)
+	} else {
+		ctx = parentCtx.Clone()
+		ctx.SetParent(parentCtx)
+	}
+	return
+}
+
+func (info *FuncInfo) ParamSpec(paramName string) ExprFuncParam {
+	for _, spec := range info.formalParams {
+		if spec.Name() == paramName {
+			return spec
+		}
+	}
+	return nil
+}
+
+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
+}

kern/function.go

@@ -14,11 +14,6 @@ type FuncTemplate func(ctx ExprContext, name string, args map[string]any) (resul
 
 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
@@ -54,17 +49,17 @@ func (functor *BaseFunctor) GetDefinitionContext() ExprContext {
 }
 
 // ---- Function Parameters
-type paramFlags uint16
+type FuncParamFlags uint16
 
 const (
-	PfDefault paramFlags = 1 << iota
+	PfDefault FuncParamFlags = 1 << iota
 	PfOptional
 	PfRepeat
 )
 
 type funcParamInfo struct {
 	name         string
-	flags        paramFlags
+	flags        FuncParamFlags
 	defaultValue any
 }
 
@@ -72,11 +67,11 @@ func NewFuncParam(name string) ExprFuncParam {
 	return &funcParamInfo{name: name}
 }
 
-func NewFuncParamFlag(name string, flags paramFlags) ExprFuncParam {
+func NewFuncParamFlag(name string, flags FuncParamFlags) ExprFuncParam {
 	return &funcParamInfo{name: name, flags: flags}
 }
 
-func NewFuncParamFlagDef(name string, flags paramFlags, defValue any) *funcParamInfo {
+func NewFuncParamFlagDef(name string, flags FuncParamFlags, defValue any) *funcParamInfo {
 	return &funcParamInfo{name: name, flags: flags, defaultValue: defValue}
 }
 

operand-func.go

@@ -70,14 +70,14 @@ func evalFuncDef(ctx kern.ExprContext, opTerm *scan.Term) (v any, err error) {
 		paramList := make([]kern.ExprFuncParam, 0, len(opTerm.Children))
 		for _, param := range opTerm.Children {
 			var defValue any
-			flags := paramFlags(0)
+			flags := kern.FuncParamFlags(0)
 			if len(param.Children) > 0 {
-				flags |= PfDefault
+				flags |= kern.PfDefault
 				if defValue, err = param.Children[0].Compute(ctx); err != nil {
 					return
 				}
 			}
-			info := NewFuncParamFlagDef(param.Source(), flags, defValue)
+			info := kern.NewFuncParamFlagDef(param.Source(), flags, defValue)
 			paramList = append(paramList, info)
 		}
 		v = newExprFunctor(ast, paramList, ctx)

operand-iterator.go

@@ -5,7 +5,9 @@
 package expr
 
 import (
+	"fmt"
 	"slices"
+	"strconv"
 	"strings"
 
 	"git.portale-stac.it/go-pkg/expr/kern"
@@ -125,7 +127,7 @@ func evalIterator(ctx kern.ExprContext, opTerm *scan.Term) (v any, err error) {
 		} else {
 			if dictIt, ok := firstChildValue.(*kern.DictType); ok {
 				var args []any
-				if args, err = evalSibling(ctx, opTerm.Children, nil); err == nil {
+				if args, err = evalSiblings(ctx, opTerm.Children, nil); err == nil {
 					v, err = NewDictIterator(dictIt, args)
 				}
 			} else {
@@ -134,24 +136,70 @@ func evalIterator(ctx kern.ExprContext, opTerm *scan.Term) (v any, err error) {
 		}
 	} else if list, ok := firstChildValue.(*kern.ListType); ok {
 		var args []any
-		if args, err = evalSibling(ctx, opTerm.Children, nil); err == nil {
+		if args, err = evalSiblings(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 {
+		if args, err = evalSiblings(ctx, opTerm.Children, intVal); err == nil {
 			v, err = NewIntIterator(args)
 		}
 	} else {
-		var list []any
+		var siblings []any
-		if list, err = evalSibling(ctx, opTerm.Children, firstChildValue); err == nil {
+		if siblings, err = evalSiblings(ctx, opTerm.Children, firstChildValue); err == nil {
-			v = NewArrayIterator(list)
+			// if v, err = evalIterIter(ctx, firstChildValue, siblings); err == nil && v == nil {
+			// if it, ok := firstChildValue.(kern.Iterator); ok {
+			// 	if len(siblings) > 1 {
+			// 		if op, ok := siblings[1].(kern.Functor); ok {
+			// 			args := make(map[string]any, len(siblings)-2)
+			// 			for i, arg := range siblings[2:] {
+			// 				args["arg"+strconv.Itoa(i+1)] = arg
+			// 			}
+			// 			v, err = NewIterIter(it, ctx, op, args)
+			// 		} else {
+			// 			err = opTerm.Children[1].Errorf("the first sibling parameter must be a functor to be used as operation for the iterator")
+			// 		}
+			// 	} else {
+			// 		v, err = NewIterIter(it, ctx, nil, nil)
+			// 	}
+			if v, err = evalIterIter(ctx, firstChildValue, siblings); err == nil && v == nil {
+				v = NewArrayIterator(siblings)
+			}
 		}
 	}
 	return
 }
 
-func evalSibling(ctx kern.ExprContext, terms []*scan.Term, firstChildValue any) (list []any, err error) {
+func evalIterIter(ctx kern.ExprContext, firstChildValue any, siblings []any) (v any, err error) {
+	var op kern.Functor
+	var args map[string]any
+
+	if it, ok := firstChildValue.(kern.Iterator); ok {
+		if len(siblings) > 1 {
+			if op, ok = siblings[1].(kern.Functor); ok {
+				args = make(map[string]any, len(siblings)-2)
+				for i, arg := range siblings[2:] {
+					switch a := arg.(type) {
+					case *kern.DictType:
+						for keyAny, item := range *a {
+							if key, ok := keyAny.(string); ok {
+								args[key] = item
+							}
+						}
+					default:
+						args["arg"+strconv.Itoa(i+1)] = arg
+					}
+				}
+			} else if op == nil {
+				return nil, fmt.Errorf("the first sibling parameter must be a functor to be used as operation for the iterator")
+			}
+		}
+		v, err = NewIterIter(it, ctx, op, args)
+	}
+	return
+}
+
+func evalSiblings(ctx kern.ExprContext, terms []*scan.Term, firstChildValue any) (list []any, err error) {
 	items := make([]any, 0, len(terms))
 	for i, tree := range terms {
 		var param any

operator-builtin.go

@@ -37,7 +37,7 @@ func evalBuiltin(ctx kern.ExprContext, opTerm *scan.Term) (v any, err error) {
 	} else {
 		var moduleSpec any
 		var it kern.Iterator
-		if it, err = NewIterator(childValue); err != nil {
+		if it, err = NewIterator(ctx, childValue, nil); err != nil {
 			return
 		}
 		for moduleSpec, err = it.Next(); err == nil; moduleSpec, err = it.Next() {

operator-default.go

@@ -111,7 +111,7 @@ func evalAssignDefault(ctx kern.ExprContext, opTerm *scan.Term) (v any, err erro
 		if functor, ok := rightValue.(kern.Functor); ok {
 			//ctx.RegisterFunc(leftTerm.source(), functor, 0, -1)
 			ctx.RegisterFunc(leftTerm.Source(), functor, kern.TypeAny, []kern.ExprFuncParam{
-				NewFuncParamFlag(kern.ParamValue, PfDefault|PfRepeat),
+				kern.NewFuncParamFlag(kern.ParamValue, kern.PfDefault|kern.PfRepeat),
 			})
 		} else {
 			v = rightValue

operator-digest.go

@@ -37,7 +37,7 @@ func evalDigest(ctx kern.ExprContext, opTerm *scan.Term) (v any, err error) {
 		return
 	}
 
-	if it, err = NewIterator(leftValue); err != nil {
+	if it, err = NewIterator(ctx, leftValue, nil); err != nil {
 		return nil, fmt.Errorf("left operand of DIGEST must be an iterable data-source; got %s", kern.TypeName(leftValue))
 	}
 

operator-filter.go

@@ -28,6 +28,7 @@ func evalFilter(ctx kern.ExprContext, opTerm *scan.Term) (v any, err error) {
 	var leftValue, rightValue any
 	var it kern.Iterator
 	var item any
+	var ok bool
 
 	if err = opTerm.CheckOperands(); err != nil {
 		return
@@ -37,8 +38,10 @@ func evalFilter(ctx kern.ExprContext, opTerm *scan.Term) (v any, err error) {
 		return
 	}
 
-	if it, err = NewIterator(leftValue); err != nil {
+	if it, ok = leftValue.(kern.Iterator); !ok {
-		return nil, fmt.Errorf("left operand of FILTER must be an iterable data-source; got %s", kern.TypeName(leftValue))
+		if it, err = NewIterator(ctx, leftValue, nil); err != nil {
+			return nil, fmt.Errorf("left operand of FILTER must be an iterable data-source; got %s", kern.TypeName(leftValue))
+		}
 	}
 
 	values := kern.NewListA()

operator-groupby.go

@@ -40,7 +40,7 @@ func evalGroupBy(ctx kern.ExprContext, opTerm *scan.Term) (v any, err error) {
 		return
 	}
 
-	if it, err = NewIterator(leftValue); err != nil {
+	if it, err = NewIterator(ctx, leftValue, nil); err != nil {
 		return nil, fmt.Errorf("left operand of MAP must be an iterable data-source; got %s", kern.TypeName(leftValue))
 	}
 

operator-join.go

@@ -41,11 +41,11 @@ func evalJoin(ctx kern.ExprContext, opTerm *scan.Term) (v any, err error) {
 		return
 	}
 
-	if itLeft, err = NewIterator(leftValue); err != nil {
+	if itLeft, err = NewIterator(ctx, leftValue, nil); err != nil {
 		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 {
+	if itRight, err = NewIterator(ctx, rightValue, nil); err != nil {
 		return nil, fmt.Errorf("right operand of JOIN must be an iterable data-source; got %s", kern.TypeName(rightValue))
 	}
 

operator-map.go

@@ -37,7 +37,7 @@ func evalMap(ctx kern.ExprContext, opTerm *scan.Term) (v any, err error) {
 		return
 	}
 
-	if it, err = NewIterator(leftValue); err != nil {
+	if it, err = NewIterator(ctx, leftValue, nil); err != nil {
 		return nil, fmt.Errorf("left operand of MAP must be an iterable data-source; got %s", kern.TypeName(leftValue))
 	}
 

plugins.go

@@ -100,7 +100,7 @@ func importPluginFromSearchPath(ctx kern.ExprContext, name any) (count int, err
 	var it kern.Iterator
 	dirList := buildSearchDirList(ctx, "plugin", ENV_EXPR_PLUGIN_PATH)
 	count = 0
-	if it, err = NewIterator(name); err != nil {
+	if it, err = NewIterator(ctx, name, nil); err != nil {
 		return
 	}
 	for moduleSpec, err = it.Next(); err == nil; moduleSpec, err = it.Next() {

simple-store.go

@@ -200,12 +200,12 @@ func (ctx *SimpleStore) GetLocalFuncInfo(name string) (info kern.ExprFunc, exist
 }
 
 func (ctx *SimpleStore) RegisterFuncInfo(info kern.ExprFunc) {
-	ctx.funcStore[info.Name()], _ = info.(*funcInfo)
+	ctx.funcStore[info.Name()], _ = info.(*kern.FuncInfo)
 }
 
 func (ctx *SimpleStore) RegisterFunc(name string, functor kern.Functor, returnType string, params []kern.ExprFuncParam) (exprFunc kern.ExprFunc, err error) {
-	var info *funcInfo
+	var info *kern.FuncInfo
-	if info, err = newFuncInfo(name, functor, returnType, params); err == nil {
+	if info, err = kern.NewFuncInfo(name, functor, returnType, params); err == nil {
 		ctx.funcStore[name] = info
 		exprFunc = info
 	}

t_funcs_test.go

@@ -100,7 +100,7 @@ func TestGoFunction(t *testing.T) {
 
 	ctx := NewSimpleStoreWithoutGlobalContext()
 	ctx.RegisterFunc("myName", kern.NewGolangFunctor(myName), kern.TypeString, []kern.ExprFuncParam{
-		NewFuncParamFlagDef("name", PfOptional|PfDefault, "Celestino Amoroso"),
+		kern.NewFuncParamFlagDef("name", kern.PfOptional|kern.PfDefault, "Celestino Amoroso"),
 	})
 
 	runCtxTestSuite(t, ctx, section, inputs)

t_iter-iter_test.go

@@ -0,0 +1,63 @@
+// Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
+// All rights reserved.
+
+// t_iter-iter_test.go
+package expr
+
+import (
+	"testing"
+
+	"git.portale-stac.it/go-pkg/expr/kern"
+)
+
+func TestIterIterator(t *testing.T) {
+	section := "Iterator"
+	inputs := []inputType{
+		/*   1 */ {`it=$(4); $(it) filter ${_}==100`, kern.NewListA(), nil},
+		/*   2 */ {`it=$(4); $(it, func(){$_}) filter ${_}==100`, kern.NewListA(), nil},
+		/*   3 */ {`it=$(4); $(it, func(arg1){arg1+$_}, 10) filter ${_}==100`, kern.NewListA(), nil},
+	}
+
+	runTestSuiteSpec(t, section, inputs, 3)
+	// runTestSuite(t, section, inputs)
+}
+
+// func TestNewIterIterator(t *testing.T) {
+// 	var it kern.Iterator
+// 	var err error
+
+// 	list := kern.NewListA("a", "b", "c", "d")
+// 	itList := NewListIterator(list, []any{1, 3, 1})
+// 	it, err = NewIterator(nil, itList, map[string]any{"op": kern.NewFunctor("test")})
+// 	if err != nil {
+// 		t.Errorf("error: %v", err)
+// 	} else {
+// 		if item, err := it.Next(); err != nil {
+// 			t.Errorf("error: %v", err)
+// 		} else if item != "b" {
+// 			t.Errorf("expected %q, got %q", "b", item)
+// 		} else {
+// 			t.Logf("Next: %v", item)
+// 		}
+// 	}
+// }
+
+// func TestNewIterIteratorNoOp(t *testing.T) {
+// 	var it kern.Iterator
+// 	var err error
+
+// 	list := kern.NewListA("a", "b", "c", "d")
+// 	itList := NewListIterator(list, []any{1, 3, 1})
+// 	it, err = NewIterator(nil, itList, nil)
+// 	if err != nil {
+// 		t.Errorf("error: %v", err)
+// 	} else {
+// 		if item, err := it.Next(); err != nil {
+// 			t.Errorf("error: %v", err)
+// 		} else if item != "b" {
+// 			t.Errorf("expected %q, got %q", "b", item)
+// 		} else {
+// 			t.Logf("Next: %v", item)
+// 		}
+// 	}
+// }

t_iter-list_test.go

@@ -61,7 +61,7 @@ func TestNewIterList2(t *testing.T) {
 
 func TestNewIterList3(t *testing.T) {
 	list := []any{"a", "b", "c", "d"}
-	it, _ := NewIterator(list)
+	it, _ := NewIterator(nil, list, nil)
 	if item, err := it.Next(); err != nil {
 		t.Errorf("error: %v", err)
 	} else if item != "a" {
@@ -73,7 +73,7 @@ func TestNewIterList3(t *testing.T) {
 
 func TestNewIterList4(t *testing.T) {
 	list := any(nil)
-	it, _ := NewIterator(list)
+	it, _ := NewIterator(nil, list, nil)
 	if _, err := it.Next(); err != io.EOF {
 		t.Errorf("error: %v", err)
 	}
@@ -81,7 +81,7 @@ func TestNewIterList4(t *testing.T) {
 
 func TestNewIterList5(t *testing.T) {
 	list := "123"
-	it, _ := NewIterator(list)
+	it, _ := NewIterator(nil, list, nil)
 	if item, err := it.Next(); err != nil {
 		t.Errorf("error: %v", err)
 	} else if item != "123" {
@@ -93,8 +93,8 @@ func TestNewIterList5(t *testing.T) {
 
 func TestNewIterList6(t *testing.T) {
 	list := kern.NewListA("a", "b", "c", "d")
-	it1, _ := NewIterator(list)
+	it1, _ := NewIterator(nil, list, nil)
-	it, _ := NewIterator(it1)
+	it, _ := NewIterator(nil, it1, nil)
 	if item, err := it.Next(); err != nil {
 		t.Errorf("error: %v", err)
 	} else if item != "a" {
@@ -106,7 +106,7 @@ func TestNewIterList6(t *testing.T) {
 
 func TestNewString(t *testing.T) {
 	list := "123"
-	it, _ := NewIterator(list)
+	it, _ := NewIterator(nil, list, nil)
 	if s := it.String(); s != "$([#1])" {
 		t.Errorf("expected $([#1]), got %s", s)
 	}