fixed some defects in the iter-list implementation

- fraction type renamed as FractionType and moved from operator-fraction.go to fraction-type.go
- ListType moved from operator-list.go to list-type.go
- all test file were renamed adding the "t_" prefix
- defined a test template in file t_temple_test.go
- new test file t_relational_test.go where relational tests are collected
- lists can now compared as set using operators <, <=, >, and >= (IMPORTANT: here = menas same content, not same list)

ast.go

@@ -127,8 +127,9 @@ func (self *ast) eval(ctx ExprContext, preset bool) (result any, err error) {
 			}
 		}
 		if err == nil {
-			result, err = self.root.compute(ctx)
+			if result, err = self.root.compute(ctx); err == nil {
-			ctx.UnsafeSetVar(ControlLastResult, result)
+				ctx.UnsafeSetVar(ControlLastResult, result)
+			}
 		}
 		// } else {
 		// 	err = errors.New("empty expression")

common-errors.go

@@ -8,48 +8,48 @@ import (
 	"fmt"
 )
 
-func errTooFewParams(minArgs, maxArgs, argCount int) (err error) {
+func errTooFewParams(funcName string, minArgs, maxArgs, argCount int) (err error) {
 	if maxArgs < 0 {
-		err = fmt.Errorf("too few params -- expected %d or more, got %d", minArgs, argCount)
+		err = fmt.Errorf("%s(): too few params -- expected %d or more, got %d", funcName, minArgs, argCount)
 	} else {
-		err = fmt.Errorf("too few params -- expected %d, got %d", minArgs, argCount)
+		err = fmt.Errorf("%s(): too few params -- expected %d, got %d", funcName, minArgs, argCount)
 	}
 	return
 }
 
-func errTooMuchParams(maxArgs, argCount int) (err error) {
+func errTooMuchParams(funcName string, maxArgs, argCount int) (err error) {
-	err = fmt.Errorf("too much params -- expected %d, got %d", maxArgs, argCount)
+	err = fmt.Errorf("%s(): too much params -- expected %d, got %d", funcName, maxArgs, argCount)
 	return
 }
 
 // --- General errors
 
 func errCantConvert(funcName string, value any, kind string) error {
-	return fmt.Errorf("%s() can't convert %T to %s", funcName, value, kind)
+	return fmt.Errorf("%s(): can't convert %s to %s", funcName, typeName(value), kind)
 }
 
 func errExpectedGot(funcName string, kind string, value any) error {
-	return fmt.Errorf("%s() expected %s, got %T (%v)", funcName, kind, value, value)
+	return fmt.Errorf("%s() expected %s, got %s (%v)", funcName, kind, typeName(value), value)
 }
 
-func errDivisionByZero(funcName string) error {
+func errFuncDivisionByZero(funcName string) error {
-	return fmt.Errorf("%s() division by zero", funcName)
+	return fmt.Errorf("%s(): division by zero", funcName)
+}
+
+func errDivisionByZero() error {
+	return fmt.Errorf("division by zero")
 }
 
 // --- Parameter errors
 
-// func errOneParam(funcName string) error {
-// 	return fmt.Errorf("%s() requires exactly one param", funcName)
-// }
-
 func errMissingRequiredParameter(funcName, paramName string) error {
 	return fmt.Errorf("%s() missing required parameter %q", funcName, paramName)
 }
 
 func errInvalidParameterValue(funcName, paramName string, paramValue any) error {
-	return fmt.Errorf("%s() invalid value %T (%v) for parameter %q", funcName, paramValue, paramValue, paramName)
+	return fmt.Errorf("%s() invalid value %s (%v) for parameter %q", funcName, typeName(paramValue), paramValue, paramName)
 }
 
 func errWrongParamType(funcName, paramName, paramType string, paramValue any) error {
-	return fmt.Errorf("%s() the %q parameter must be a %s, got a %T (%v)", funcName, paramName, paramType, paramValue, paramValue)
+	return fmt.Errorf("%s() the %q parameter must be a %s, got a %s (%v)", funcName, paramName, paramType, typeName(paramValue), paramValue)
 }

common-params.go

@@ -16,15 +16,6 @@ const (
 	paramEnd       = "end"
 	paramValue     = "value"
 	paramEllipsis  = "..."
-	typeFilepath   = "filepath"
+	paramFilepath  = "filepath"
-	typeDirpath    = "dirpath"
+	paramDirpath   = "dirpath"
 )
-
-// const (
-// 	typeInteger  = "int"
-// 	typeFloat    = "float"
-// 	typeString   = "string"
-// 	typeFraction = "fract"
-// 	typeList     = "list"
-// 	typeDict     = "dict"
-// )

common-type-names.go

@@ -13,5 +13,6 @@ const (
 	typeInt      = "integer"
 	typeItem     = "item"
 	typeNumber   = "number"
+	typePair     = "pair"
 	typeString   = "string"
 )

context.go

@@ -9,6 +9,7 @@ type Functor interface {
 	Invoke(ctx ExprContext, name string, args []any) (result any, err error)
 	SetFunc(info ExprFunc)
 	GetFunc() ExprFunc
+	GetParams() []ExprFuncParam
 }
 
 // ---- Function Param Info
@@ -34,6 +35,7 @@ type ExprFunc interface {
 // ----Expression Context
 type ExprContext interface {
 	Clone() ExprContext
+	Merge(ctx ExprContext)
 	GetVar(varName string) (value any, exists bool)
 	SetVar(varName string, value any)
 	UnsafeSetVar(varName string, value any)

dict-type.go

@@ -0,0 +1,130 @@
+// Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
+// All rights reserved.
+
+// dict-type.go
+package expr
+
+import (
+	"fmt"
+	"reflect"
+	"strings"
+)
+
+type DictType map[any]any
+
+func newDict(dictAny map[any]*term) (dict *DictType) {
+	var d DictType
+	if dictAny != nil {
+		d = make(DictType, len(dictAny))
+		for i, item := range dictAny {
+			d[i] = item
+		}
+	} else {
+		d = make(DictType)
+	}
+	dict = &d
+	return
+}
+
+func (dict *DictType) toMultiLine(sb *strings.Builder, indent int) {
+	sb.WriteString(strings.Repeat("\t", indent))
+	sb.WriteString("{\n")
+
+	first := true
+	for name, value := range *dict {
+		if first {
+			first = false
+		} else {
+			sb.WriteByte(',')
+			sb.WriteByte('\n')
+		}
+
+		sb.WriteString(strings.Repeat("\t", indent+1))
+		if key, ok := name.(string); ok {
+			sb.WriteString(string('"') + key + string('"'))
+		} else {
+			sb.WriteString(fmt.Sprintf("%v", name))
+		}
+		sb.WriteString(": ")
+		if f, ok := value.(Formatter); ok {
+			sb.WriteString(f.ToString(MultiLine))
+		} else if _, ok = value.(Functor); ok {
+			sb.WriteString("func(){}")
+		} else {
+			sb.WriteString(fmt.Sprintf("%v", value))
+		}
+	}
+	sb.WriteString(strings.Repeat("\t", indent))
+	sb.WriteString("\n}")
+}
+
+func (dict *DictType) ToString(opt FmtOpt) string {
+	var sb strings.Builder
+	if opt&MultiLine != 0 {
+		dict.toMultiLine(&sb, 0)
+	} else {
+		sb.WriteByte('{')
+		first := true
+		for key, value := range *dict {
+			if first {
+				first = false
+			} else {
+				sb.WriteString(", ")
+			}
+			if s, ok := key.(string); ok {
+				sb.WriteString(string('"') + s + string('"'))
+			} else {
+				sb.WriteString(fmt.Sprintf("%v", key))
+			}
+			sb.WriteString(": ")
+			if formatter, ok := value.(Formatter); ok {
+				sb.WriteString(formatter.ToString(opt))
+			} else if t, ok := value.(*term); ok {
+				sb.WriteString(t.String())
+			} else {
+				sb.WriteString(fmt.Sprintf("%#v", value))
+			}
+		}
+		sb.WriteByte('}')
+	}
+	return sb.String()
+}
+
+func (dict *DictType) String() string {
+	return dict.ToString(0)
+}
+
+func (dict *DictType) TypeName() string {
+	return "dict"
+}
+
+func (dict *DictType) hasKey(target any) (ok bool) {
+	for key := range *dict {
+		if ok = reflect.DeepEqual(key, target); ok {
+			break
+		}
+	}
+	return
+}
+
+func (dict *DictType) clone() (c *DictType) {
+	c = newDict(nil)
+	for k, v := range *dict {
+		(*c)[k] = v
+	}
+	return
+}
+
+func (dict *DictType) merge(second *DictType) {
+	if second != nil {
+		for k, v := range *second {
+			(*dict)[k] = v
+		}
+	}
+}
+
+func (dict *DictType) setItem(key any, value any) (err error) {
+	(*dict)[key]=value
+	return
+}
+

doc/Expr.adoc

@@ -22,7 +22,7 @@ Expressions calculator
 
 toc::[]
 
-#TODO: Work in progress (last update on 2024/05/20, 06:58 a.m.)#
+#TODO: Work in progress (last update on 2024/06/02, 08:18 a.m.)#
 
 == Expr
 _Expr_ is a GO package capable of analysing, interpreting and calculating expressions.
@@ -615,7 +615,10 @@ The table below shows all supported operators by decreasing priorities.
 |===
 
 == Functions
-Functions in _Expr_ are very similar to functions in many programming languages.
+Functions in _Expr_ are very similar to functions available in many programming languages. Actually, _Expr_ supports two types of function, _expr-functions_ and _go-functions_.
+
+* _expr-functions_ are defined using _Expr_'s syntax. They can be passed as arguments to other functions and can be returned from functions. Moreover, they bind themselves to the defining context, thus becoming closures.
+* _go-functions_ are regular Golang functions callable from _Expr_ expressions. They are defined in Golang source files called _modules_ and compiled within the _Expr_ package. To make Golang functions available in _Expr_ contextes, it is required to _import_ the module in which they are defined.
 
 In _Expr_ functions compute values in a local context (scope) that do not make effects on the calling context. This is the normal behavior. Using the reference operator [blue]`@` it is possibile to export local definition to the calling context.
 

doc/Expr.html

@@ -585,7 +585,7 @@ pre.rouge .ss {
 <div class="sectionbody">
 <!-- toc disabled -->
 <div class="paragraph">
-<p><mark>TODO: Work in progress (last update on 2024/05/20, 06:58 a.m.)</mark></p>
+<p><mark>TODO: Work in progress (last update on 2024/06/02, 08:18 a.m.)</mark></p>
 </div>
 </div>
 </div>
@@ -1609,7 +1609,7 @@ These operators have a high priority, in particular higher than the operator <co
 <td class="tableblock halign-center valign-top"><p class="tableblock"><code class="blue">.</code></p></td>
 <td class="tableblock halign-center valign-top"><p class="tableblock"><em>Infix</em></p></td>
 <td class="tableblock halign-center valign-top"><p class="tableblock"><em>Dict item</em></p></td>
-<td class="tableblock halign-center valign-top"><p class="tableblock"><em>dict</em> <code>""</code> <em>any</em> &#8594; <em>any</em></p></td>
+<td class="tableblock halign-center valign-top"><p class="tableblock"><em>dict</em> <code>"."</code> <em>any</em> &#8594; <em>any</em></p></td>
 </tr>
 <tr>
 <td class="tableblock halign-center valign-top" rowspan="2"><p class="tableblock"><strong>INC</strong></p></td>
@@ -1834,7 +1834,17 @@ These operators have a high priority, in particular higher than the operator <co
 <h2 id="_functions"><a class="anchor" href="#_functions"></a><a class="link" href="#_functions">6. Functions</a></h2>
 <div class="sectionbody">
 <div class="paragraph">
-<p>Functions in <em>Expr</em> are very similar to functions in many programming languages.</p>
+<p>Functions in <em>Expr</em> are very similar to functions available in many programming languages. Actually, <em>Expr</em> supports two types of function, <em>expr-functions</em> and <em>go-functions</em>.</p>
+</div>
+<div class="ulist">
+<ul>
+<li>
+<p><em>expr-functions</em> are defined using <em>Expr</em>'s syntax. They can be passed as arguments to other functions and can be returned from functions. Moreover, they bind themselves to the defining context, thus becoming closures.</p>
+</li>
+<li>
+<p><em>go-functions</em> are regular Golang functions callable from <em>Expr</em> expressions. They are defined in Golang source files called <em>modules</em> and compiled within the <em>Expr</em> package. To make Golang functions available in <em>Expr</em> contextes, it is required to <em>import</em> the module in which they are defined.</p>
+</li>
+</ul>
 </div>
 <div class="paragraph">
 <p>In <em>Expr</em> functions compute values in a local context (scope) that do not make effects on the calling context. This is the normal behavior. Using the reference operator <code class="blue">@</code> it is possibile to export local definition to the calling context.</p>
@@ -1874,7 +1884,7 @@ These operators have a high priority, in particular higher than the operator <co
 </div>
 <div id="footer">
 <div id="footer-text">
-Last updated 2024-05-20 09:40:23 +0200
+Last updated 2024-06-03 06:26:03 +0200
 </div>
 </div>
 </body>

expr_test.go

@@ -1,82 +0,0 @@
-// Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
-// All rights reserved.
-
-// expr_test.go
-package expr
-
-import (
-	"strings"
-	"testing"
-)
-
-func TestExpr(t *testing.T) {
-	type inputType struct {
-		source     string
-		wantResult any
-		wantErr    error
-	}
-
-	inputs := []inputType{
-		/*   1 */ {`0?{}`, nil, nil},
-		/*   2 */ {`fact=func(n){(n)?{1}::{n*fact(n-1)}}; fact(5)`, int64(120), nil},
-		/*   3 */ {`f=openFile("test-file.txt"); line=readFile(f); closeFile(f); line`, "uno", nil},
-		/*   4 */ {`mynot=func(v){int(v)?{true}::{false}}; mynot(0)`, true, nil},
-		/*   5 */ {`1 ? {1} : [1+0] {3*(1+1)}`, int64(6), nil},
-		/*   6 */ {`
-		ds={
-			"init":func(end){@end=end; @current=0 but true},
-			"current":func(){current},
-			"next":func(){
-				((next=current+1) <= end) ? [true] {@current=next but current} :: {nil}
-			}
-		};
-		it=$(ds,3);
-		it++;
-		it++
-`, int64(1), nil},
-	}
-
-	succeeded := 0
-	failed := 0
-
-	for i, input := range inputs {
-		var expr Expr
-		var gotResult any
-		var gotErr error
-
-		ctx := NewSimpleStore()
-		// ImportMathFuncs(ctx)
-		// ImportImportFunc(ctx)
-		ImportOsFuncs(ctx)
-		parser := NewParser(ctx)
-
-		logTest(t, i+1, "Expr", input.source, input.wantResult, input.wantErr)
-
-		r := strings.NewReader(input.source)
-		scanner := NewScanner(r, DefaultTranslations())
-
-		good := true
-		if expr, gotErr = parser.Parse(scanner); gotErr == nil {
-			gotResult, gotErr = expr.Eval(ctx)
-		}
-
-		if gotResult != input.wantResult {
-			t.Errorf("%d: %q -> result = %v [%T], want %v [%T]", i+1, input.source, gotResult, gotResult, input.wantResult, input.wantResult)
-			good = false
-		}
-
-		if gotErr != input.wantErr {
-			if input.wantErr == nil || gotErr == nil || (gotErr.Error() != input.wantErr.Error()) {
-				t.Errorf("%d: %q -> err = <%v>, want <%v>", i+1, input.source, gotErr, input.wantErr)
-				good = false
-			}
-		}
-
-		if good {
-			succeeded++
-		} else {
-			failed++
-		}
-	}
-	t.Logf("test count: %d, succeeded count: %d, failed count: %d", len(inputs), succeeded, failed)
-}

formatter.go

@@ -51,8 +51,10 @@ type Typer interface {
 	TypeName() string
 }
 
-func getTypeName(v any) (name string) {
+func typeName(v any) (name string) {
-	if typer, ok := v.(Typer); ok {
+	if v == nil {
+		name = "nil"
+	} else if typer, ok := v.(Typer); ok {
 		name = typer.TypeName()
 	} else if IsInteger(v) {
 		name = "integer"

fraction-type.go

@@ -0,0 +1,359 @@
+// Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
+// All rights reserved.
+
+// fraction-type.go
+package expr
+
+//https://www.youmath.it/lezioni/algebra-elementare/lezioni-di-algebra-e-aritmetica-per-scuole-medie/553-dalle-frazioni-a-numeri-decimali.html
+
+import (
+	"errors"
+	"fmt"
+	"math"
+	"strconv"
+	"strings"
+)
+
+type FractionType struct {
+	num, den int64
+}
+
+func newFraction(num, den int64) *FractionType {
+	num, den = simplifyIntegers(num, den)
+	return &FractionType{num, den}
+}
+
+func float64ToFraction(f float64) (fract *FractionType, err error) {
+	var sign string
+	intPart, decPart := math.Modf(f)
+	if decPart < 0.0 {
+		sign = "-"
+		intPart = -intPart
+		decPart = -decPart
+	}
+	dec := fmt.Sprintf("%.12f", decPart)
+	s := fmt.Sprintf("%s%.f%s", sign, intPart, dec[1:])
+	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) {
+	var num, den int64
+	var sign int64 = 1
+	var parts []string
+	if len(s) == 0 {
+		goto exit
+	}
+	if s[0] == '-' {
+		sign = int64(-1)
+		s = s[1:]
+	} else if s[0] == '+' {
+		s = s[1:]
+	}
+	if strings.HasSuffix(s, "()") {
+		s = s[0 : len(s)-2]
+	}
+	parts = strings.SplitN(s, ".", 2)
+	if num, err = strconv.ParseInt(parts[0], 10, 64); err != nil {
+		return
+	}
+	if len(parts) == 1 {
+		f = newFraction(sign*num, 1)
+	} else if len(parts) == 2 {
+		subParts := strings.SplitN(parts[1], "(", 2)
+		if len(subParts) == 1 {
+			den = 1
+			dec := parts[1]
+			lsd := len(dec)
+			for i := lsd - 1; i >= 0 && dec[i] == '0'; i-- {
+				lsd--
+			}
+			for _, c := range dec[0:lsd] {
+				if c < '0' || c > '9' {
+					return nil, errExpectedGot("fract", "digit", c)
+				}
+				num = num*10 + int64(c-'0')
+				den = den * 10
+			}
+			f = newFraction(sign*num, den)
+		} else if len(subParts) == 2 {
+			sub := num
+			mul := int64(1)
+			for _, c := range subParts[0] {
+				if c < '0' || c > '9' {
+					return nil, errExpectedGot("fract", "digit", c)
+				}
+				num = num*10 + int64(c-'0')
+				sub = sub*10 + int64(c-'0')
+				mul *= 10
+			}
+			if len(subParts) == 2 {
+				if s[len(s)-1] != ')' {
+					goto exit
+				}
+				p := subParts[1][0 : len(subParts[1])-1]
+				for _, c := range p {
+					if c < '0' || c > '9' {
+						return nil, errExpectedGot("fract", "digit", c)
+					}
+					num = num*10 + int64(c-'0')
+					den = den*10 + 9
+				}
+				den *= mul
+			}
+			num -= sub
+			f = newFraction(sign*num, den)
+		}
+	}
+exit:
+	if f == nil {
+		err = errors.New("bad syntax")
+	}
+	return
+}
+
+func (f *FractionType) toFloat() float64 {
+	return float64(f.num) / float64(f.den)
+}
+
+func (f *FractionType) String() string {
+	return f.ToString(0)
+}
+
+func (f *FractionType) ToString(opt FmtOpt) string {
+	var sb strings.Builder
+	if opt&MultiLine == 0 {
+		sb.WriteString(fmt.Sprintf("%d|%d", f.num, f.den))
+	} else {
+		var s, num string
+		if f.num < 0 && opt&TTY == 0 {
+			num = strconv.FormatInt(-f.num, 10)
+			s = "-"
+		} else {
+			num = strconv.FormatInt(f.num, 10)
+		}
+		den := strconv.FormatInt(f.den, 10)
+		size := max(len(num), len(den))
+		if opt&TTY != 0 {
+			sb.WriteString(fmt.Sprintf("\x1b[4m%[1]*s\x1b[0m\n", -size, fmt.Sprintf("%[1]*s", (size+len(num))/2, s+num)))
+		} else {
+			if len(s) > 0 {
+				sb.WriteString("  ")
+			}
+			sb.WriteString(fmt.Sprintf("%[1]*s", -size, fmt.Sprintf("%[1]*s", (size+len(num))/2, num)))
+			sb.WriteByte('\n')
+			if len(s) > 0 {
+				sb.WriteString(s)
+				sb.WriteByte(' ')
+			}
+			sb.WriteString(strings.Repeat("-", size))
+			sb.WriteByte('\n')
+			if len(s) > 0 {
+				sb.WriteString("  ")
+			}
+		}
+		sb.WriteString(fmt.Sprintf("%[1]*s", -size, fmt.Sprintf("%[1]*s", (size+len(den))/2, den)))
+	}
+
+	return sb.String()
+}
+
+func (f *FractionType) TypeName() string {
+	return "fraction"
+}
+
+// -------- fraction utility functions
+
+// greatest common divider
+func gcd(a, b int64) (g int64) {
+	if a < 0 {
+		a = -a
+	}
+	if b < 0 {
+		b = -b
+	}
+	if a < b {
+		a, b = b, a
+	}
+	r := a % b
+	for r > 0 {
+		a, b = b, r
+		r = a % b
+	}
+	g = b
+	return
+}
+
+// lower common multiple
+func lcm(a, b int64) (l int64) {
+	g := gcd(a, b)
+	l = a * b / g
+	return
+}
+
+// Sum two fractions
+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)
+	return
+}
+
+// Multiply two fractions
+func mulFract(f1, f2 *FractionType) (prod *FractionType) {
+	prod = newFraction(f1.num*f2.num, f1.den*f2.den)
+	return
+}
+
+func anyToFract(v any) (f *FractionType, err error) {
+	var ok bool
+	if f, ok = v.(*FractionType); !ok {
+		if n, ok := v.(int64); ok {
+			f = intToFraction(n)
+		}
+	}
+	if f == nil {
+		err = errExpectedGot("fract", typeFraction, v)
+	}
+	return
+}
+
+func anyPairToFract(v1, v2 any) (f1, f2 *FractionType, err error) {
+	if f1, err = anyToFract(v1); err != nil {
+		return
+	}
+	if f2, err = anyToFract(v2); err != nil {
+		return
+	}
+	return
+}
+
+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)
+	if f.num == 0 {
+		sum = 0
+	} else {
+		sum = simplifyFraction(f)
+	}
+	return
+}
+
+// Returns
+//
+//		 <0 if af1 < af2
+//		 =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) {
+	var f1, f2 *FractionType
+	if f1, f2, err = anyPairToFract(af1, af2); err != nil {
+		return
+	}
+	result = cmpFract(f1, f2)
+	return
+}
+
+// Returns
+//
+//	<0 if af1 < af2
+//	=0 if af1 == af2
+//	>0 if af1 > af2
+func cmpFract(f1, f2 *FractionType) (result int) {
+	f2.num = -f2.num
+	f := sumFract(f1, f2)
+	if f.num < 0 {
+		result = -1
+	} else if f.num > 0 {
+		result = 1
+	} else {
+		result = 0
+	}
+	return
+}
+
+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)
+	if f.num == 0 {
+		sum = 0
+	} else {
+		sum = simplifyFraction(f)
+	}
+	return
+}
+
+func mulAnyFract(af1, af2 any) (prod any, err error) {
+	var f1, f2 *FractionType
+	if f1, f2, err = anyPairToFract(af1, af2); err != nil {
+		return
+	}
+	if f1.num == 0 || f2.num == 0 {
+		prod = 0
+	} else {
+		f := &FractionType{f1.num * f2.num, f1.den * f2.den}
+		prod = simplifyFraction(f)
+	}
+	return
+}
+
+func divAnyFract(af1, af2 any) (quot any, err error) {
+	var f1, f2 *FractionType
+	if f1, f2, err = anyPairToFract(af1, af2); err != nil {
+		return
+	}
+	if f2.num == 0 {
+		err = errors.New("division by zero")
+		return
+		return
+	}
+	if f1.num == 0 || f2.den == 0 {
+		quot = 0
+	} else {
+		f := &FractionType{f1.num * f2.den, f1.den * f2.num}
+		quot = simplifyFraction(f)
+	}
+	return
+}
+
+func simplifyFraction(f *FractionType) (v any) {
+	f.num, f.den = simplifyIntegers(f.num, f.den)
+	if f.den == 1 {
+		v = f.num
+	} else {
+		v = &FractionType{f.num, f.den}
+	}
+	return v
+}
+
+func simplifyIntegers(num, den int64) (a, b int64) {
+	if num == 0 {
+		return 0, 1
+	}
+	if den == 0 {
+		panic("fraction with denominator == 0")
+	}
+	if den < 0 {
+		den = -den
+		num = -num
+	}
+	g := gcd(num, den)
+	a = num / g
+	b = den / g
+	return
+}
+
+func intToFraction(n int64) *FractionType {
+	return &FractionType{n, 1}
+}
+
+func isFraction(v any) (ok bool) {
+	_, ok = v.(*FractionType)
+	return ok
+}

func-base.go

@@ -58,7 +58,7 @@ func boolFunc(ctx ExprContext, name string, args []any) (result any, err error)
 	switch v := args[0].(type) {
 	case int64:
 		result = (v != 0)
-	case *fraction:
+	case *FractionType:
 		result = v.num != 0
 	case float64:
 		result = v != 0.0
@@ -112,7 +112,7 @@ func decFunc(ctx ExprContext, name string, args []any) (result any, err error) {
 		if f, err = strconv.ParseFloat(v, 64); err == nil {
 			result = f
 		}
-	case *fraction:
+	case *FractionType:
 		result = v.toFloat()
 	default:
 		err = errCantConvert(name, v, "float")
@@ -129,7 +129,7 @@ func fractFunc(ctx ExprContext, name string, args []any) (result any, err error)
 			if den, ok = args[1].(int64); !ok {
 				err = errExpectedGot(name, "integer", args[1])
 			} else if den == 0 {
-				err = errDivisionByZero(name)
+				err = errFuncDivisionByZero(name)
 			}
 		}
 		if err == nil {
@@ -145,7 +145,7 @@ func fractFunc(ctx ExprContext, name string, args []any) (result any, err error)
 		}
 	case string:
 		result, err = makeGeneratingFraction(v)
-	case *fraction:
+	case *FractionType:
 		result = v
 	default:
 		err = errCantConvert(name, v, "float")

func-fmt.go

@@ -0,0 +1,36 @@
+// Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
+// All rights reserved.
+
+// func-fmt.go
+package expr
+
+import "fmt"
+
+func printFunc(ctx ExprContext, name string, args []any) (result any, err error) {
+	var n int
+	if n, err = fmt.Print(args...); err == nil {
+		result = int64(n)
+	}
+	return
+}
+
+func printLnFunc(ctx ExprContext, name string, args []any) (result any, err error) {
+	var n int
+	if n, err = fmt.Println(args...); err == nil {
+		result = int64(n)
+	}
+	return
+}
+
+func ImportFmtFuncs(ctx ExprContext) {
+	ctx.RegisterFunc("print", newGolangFunctor(printFunc), typeInt, []ExprFuncParam{
+		newFuncParamFlag(paramItem, pfRepeat),
+	})
+	ctx.RegisterFunc("println", newGolangFunctor(printLnFunc), typeInt, []ExprFuncParam{
+		newFuncParamFlag(paramItem, pfRepeat),
+	})
+}
+
+func init() {
+	registerImport("fmt", ImportFmtFuncs, "String and console formatting functions")
+}

func-import.go

@@ -138,10 +138,10 @@ func doImport(ctx ExprContext, name string, dirList []string, it Iterator) (resu
 
 func ImportImportFuncs(ctx ExprContext) {
 	ctx.RegisterFunc("import", newGolangFunctor(importFunc), typeAny, []ExprFuncParam{
-		newFuncParamFlag(typeFilepath, pfRepeat),
+		newFuncParamFlag(paramFilepath, pfRepeat),
 	})
 	ctx.RegisterFunc("importAll", newGolangFunctor(importAllFunc), typeAny, []ExprFuncParam{
-		newFuncParamFlag(typeFilepath, pfRepeat),
+		newFuncParamFlag(paramFilepath, pfRepeat),
 	})
 }
 

func-math.go

@@ -21,7 +21,7 @@ func doAdd(ctx ExprContext, name string, it Iterator, count, level int) (result
 	var sumAsFloat, sumAsFract bool
 	var floatSum float64 = 0.0
 	var intSum int64 = 0
-	var fractSum *fraction
+	var fractSum *FractionType
 	var v any
 
 	level++
@@ -61,9 +61,9 @@ func doAdd(ctx ExprContext, name string, it Iterator, count, level int) (result
 		if sumAsFloat {
 			floatSum += numAsFloat(v)
 		} else if sumAsFract {
-			var item *fraction
+			var item *FractionType
 			var ok bool
-			if item, ok = v.(*fraction); !ok {
+			if item, ok = v.(*FractionType); !ok {
 				iv, _ := v.(int64)
 				item = newFraction(iv, 1)
 			}
@@ -95,7 +95,7 @@ func doMul(ctx ExprContext, name string, it Iterator, count, level int) (result
 	var mulAsFloat, mulAsFract bool
 	var floatProd float64 = 1.0
 	var intProd int64 = 1
-	var fractProd *fraction
+	var fractProd *FractionType
 	var v any
 
 	level++
@@ -136,9 +136,9 @@ func doMul(ctx ExprContext, name string, it Iterator, count, level int) (result
 		if mulAsFloat {
 			floatProd *= numAsFloat(v)
 		} else if mulAsFract {
-			var item *fraction
+			var item *FractionType
 			var ok bool
-			if item, ok = v.(*fraction); !ok {
+			if item, ok = v.(*FractionType); !ok {
 				iv, _ := v.(int64)
 				item = newFraction(iv, 1)
 			}
@@ -168,11 +168,11 @@ func mulFunc(ctx ExprContext, name string, args []any) (result any, err error) {
 
 func ImportMathFuncs(ctx ExprContext) {
 	ctx.RegisterFunc("add", &golangFunctor{f: addFunc}, typeNumber, []ExprFuncParam{
-		newFuncParamFlagDef(paramValue, pfOptional|pfRepeat, 0),
+		newFuncParamFlagDef(paramValue, pfOptional|pfRepeat, int64(0)),
 	})
 
 	ctx.RegisterFunc("mul", &golangFunctor{f: mulFunc}, typeNumber, []ExprFuncParam{
-		newFuncParamFlagDef(paramValue, pfOptional|pfRepeat, 1),
+		newFuncParamFlagDef(paramValue, pfOptional|pfRepeat, int64(1)),
 	})
 }
 

func-os.go

@@ -20,6 +20,14 @@ type osWriter struct {
 	writer *bufio.Writer
 }
 
+func (h *osWriter) TypeName() string {
+	return "osWriter"
+}
+
+func (h *osWriter) String() string {
+	return "writer"
+}
+
 func (h *osWriter) getFile() *os.File {
 	return h.fh
 }
@@ -29,66 +37,73 @@ type osReader struct {
 	reader *bufio.Reader
 }
 
+func (h *osReader) TypeName() string {
+	return "osReader"
+}
+
+func (h *osReader) String() string {
+	return "reader"
+}
+
 func (h *osReader) getFile() *os.File {
 	return h.fh
 }
 
-func createFileFunc(ctx ExprContext, name string, args []any) (result any, err error) {
+func errMissingFilePath(funcName string) error {
-	var filePath string
+	return fmt.Errorf("%s(): missing or invalid file path", funcName)
-	if len(args) > 0 {
+}
-		filePath, _ = args[0].(string)
-	}
 
-	if len(filePath) > 0 {
+func errInvalidFileHandle(funcName string, v any) error {
+	if v != nil {
+		return fmt.Errorf("%s(): invalid file handle %v [%T]", funcName, v, v)
+	} else {
+		return fmt.Errorf("%s(): invalid file handle", funcName)
+	}
+}
+
+func createFileFunc(ctx ExprContext, name string, args []any) (result any, err error) {
+	if filePath, ok := args[0].(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)}
 		}
 	} else {
-		err = fmt.Errorf("%s(): missing the file path", name)
+		err = errMissingFilePath("createFile")
 	}
 	return
 }
 
 func openFileFunc(ctx ExprContext, name string, args []any) (result any, err error) {
-	var filePath string
+	if filePath, ok := args[0].(string); ok && len(filePath) > 0 {
-	if len(args) > 0 {
-		filePath, _ = args[0].(string)
-	}
-
-	if len(filePath) > 0 {
 		var fh *os.File
 		if fh, err = os.Open(filePath); err == nil {
 			result = &osReader{fh: fh, reader: bufio.NewReader(fh)}
 		}
 	} else {
-		err = fmt.Errorf("%s(): missing the file path", name)
+		err = errMissingFilePath("openFile")
 	}
 	return
 }
 
 func appendFileFunc(ctx ExprContext, name string, args []any) (result any, err error) {
-	var filePath string
+	if filePath, ok := args[0].(string); ok && len(filePath) > 0 {
-	if len(args) > 0 {
-		filePath, _ = args[0].(string)
-	}
-
-	if 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)}
 		}
 	} else {
-		err = fmt.Errorf("%s(): missing the file path", name)
+		err = errMissingFilePath("openFile")
 	}
 	return
 }
 
 func closeFileFunc(ctx ExprContext, name string, args []any) (result any, err error) {
 	var handle osHandle
+	var invalidFileHandle any
+	var ok bool
 
-	if len(args) > 0 {
+	if handle, ok = args[0].(osHandle); !ok {
-		handle, _ = args[0].(osHandle)
+		invalidFileHandle = args[0]
 	}
 
 	if handle != nil {
@@ -96,12 +111,14 @@ func closeFileFunc(ctx ExprContext, name string, args []any) (result any, err er
 			if w, ok := handle.(*osWriter); ok {
 				err = w.writer.Flush()
 			}
+
 			if err == nil {
 				err = fh.Close()
 			}
 		}
-	} else {
+	}
-		err = fmt.Errorf("%s(): invalid file handle", name)
+	if err == nil && (handle == nil || invalidFileHandle != nil) {
+		err = errInvalidFileHandle("closeFileFunc", handle)
 	}
 	result = err == nil
 	return
@@ -109,63 +126,75 @@ func closeFileFunc(ctx ExprContext, name string, args []any) (result any, err er
 
 func writeFileFunc(ctx ExprContext, name string, args []any) (result any, err error) {
 	var handle osHandle
+	var invalidFileHandle any
+	var ok bool
 
-	if len(args) > 0 {
+	if handle, ok = args[0].(osHandle); !ok {
-		handle, _ = args[0].(osHandle)
+		invalidFileHandle = args[0]
 	}
 
 	if handle != nil {
-		if fh := handle.getFile(); fh != nil {
+		if w, ok := handle.(*osWriter); ok {
-			if w, ok := handle.(*osWriter); ok {
+			result, err = fmt.Fprint(w.writer, args[1:]...)
-				result, err = fmt.Fprint(w.writer, args[1:]...)
+		} else {
-			}
+			invalidFileHandle = handle
 		}
 	}
+
+	if err == nil && (handle == nil || invalidFileHandle != nil) {
+		err = errInvalidFileHandle("writeFileFunc", invalidFileHandle)
+	}
 	return
 }
 
 func readFileFunc(ctx ExprContext, name string, args []any) (result any, err error) {
 	var handle osHandle
+	var invalidFileHandle any
+	var ok bool
+
 	result = nil
-	if len(args) > 0 {
+	if handle, ok = args[0].(osHandle); !ok || args[0] == nil {
-		handle, _ = args[0].(osHandle)
+		invalidFileHandle = args[0]
 	}
 
 	if handle != nil {
-		if fh := handle.getFile(); fh != nil {
+		if r, ok := handle.(*osReader); ok {
-			if r, ok := handle.(*osReader); ok {
+			var limit byte = '\n'
-				var limit byte = '\n'
+			var v string
-				var v string
+			if s, ok := args[1].(string); ok && len(s) > 0 {
-				if len(args) > 1 {
+				limit = s[0]
-					if s, ok := args[1].(string); ok && len(s) > 0 {
+			}
-						limit = s[0]
+
-					}
+			if v, err = r.reader.ReadString(limit); err == nil {
-				}
+				if len(v) > 0 && v[len(v)-1] == limit {
-				if v, err = r.reader.ReadString(limit); err == nil {
+					result = v[0 : len(v)-1]
-					if len(v) > 0 && v[len(v)-1] == limit {
+				} else {
-						result = v[0 : len(v)-1]
+					result = v
-					} else {
-						result = v
-					}
-				}
-				if err == io.EOF {
-					err = nil
 				}
 			}
+			if err == io.EOF {
+				err = nil
+			}
+		} else {
+			invalidFileHandle = handle
 		}
 	}
+
+	if err == nil && (handle == nil || invalidFileHandle != nil) {
+		err = errInvalidFileHandle("readFileFunc", invalidFileHandle)
+	}
 	return
 }
 
 func ImportOsFuncs(ctx ExprContext) {
 	ctx.RegisterFunc("openFile", newGolangFunctor(openFileFunc), typeHandle, []ExprFuncParam{
-		newFuncParam(typeFilepath),
+		newFuncParam(paramFilepath),
 	})
 	ctx.RegisterFunc("appendFile", newGolangFunctor(appendFileFunc), typeHandle, []ExprFuncParam{
-		newFuncParam(typeFilepath),
+		newFuncParam(paramFilepath),
 	})
 	ctx.RegisterFunc("createFile", newGolangFunctor(createFileFunc), typeHandle, []ExprFuncParam{
-		newFuncParam(typeFilepath),
+		newFuncParam(paramFilepath),
 	})
 	ctx.RegisterFunc("writeFile", newGolangFunctor(writeFileFunc), typeInt, []ExprFuncParam{
 		newFuncParam(typeHandle),
@@ -173,7 +202,7 @@ func ImportOsFuncs(ctx ExprContext) {
 	})
 	ctx.RegisterFunc("readFile", newGolangFunctor(readFileFunc), typeString, []ExprFuncParam{
 		newFuncParam(typeHandle),
-		newFuncParamFlagDef("limitCh", pfOptional, "\\n"),
+		newFuncParamFlagDef("limitCh", pfOptional, "\n"),
 	})
 	ctx.RegisterFunc("closeFile", newGolangFunctor(closeFileFunc), typeBoolean, []ExprFuncParam{
 		newFuncParam(typeHandle),

func-string.go

@@ -65,19 +65,19 @@ func subStrFunc(ctx ExprContext, name string, args []any) (result any, err error
 	if source, ok = args[0].(string); !ok {
 		return nil, errWrongParamType(name, paramSource, typeString, args[0])
 	}
-	if len(args) > 1 {
+
-		if start, err = toInt(args[1], name+"()"); err != nil {
+	if start, err = toInt(args[1], name+"()"); err != nil {
-			return
+		return
-		}
-		if len(args) > 2 {
-			if count, err = toInt(args[2], name+"()"); err != nil {
-				return
-			}
-		}
-		if start < 0 {
-			start = len(source) + start
-		}
 	}
+
+	if count, err = toInt(args[2], name+"()"); err != nil {
+		return
+	}
+
+	if start < 0 {
+		start = len(source) + start
+	}
+
 	if count < 0 {
 		count = len(source) - start
 	}
@@ -152,18 +152,17 @@ func splitStrFunc(ctx ExprContext, name string, args []any) (result any, err err
 	if source, ok = args[0].(string); !ok {
 		return result, errWrongParamType(name, paramSource, typeString, args[0])
 	}
-	if len(args) >= 2 {
+
-		if sep, ok = args[1].(string); !ok {
+	if sep, ok = args[1].(string); !ok {
-			return nil, fmt.Errorf("separator param must be string, got %T (%v)", args[1], args[1])
+		return nil, fmt.Errorf("separator param must be string, got %T (%v)", args[1], args[1])
-		}
-		if len(args) >= 3 {
-			if count64, ok := args[2].(int64); ok { // TODO replace type assertion with toInt()
-				count = int(count64)
-			} else {
-				return nil, fmt.Errorf("part count must be integer, got %T (%v)", args[2], args[2])
-			}
-		}
 	}
+
+	if count64, ok := args[2].(int64); ok { // TODO replace type assertion with toInt()
+		count = int(count64)
+	} else {
+		return nil, fmt.Errorf("part count must be integer, got %T (%v)", args[2], args[2])
+	}
+
 	if count > 0 {
 		parts = strings.SplitN(source, sep, count)
 	} else if count < 0 {
@@ -185,19 +184,19 @@ func splitStrFunc(ctx ExprContext, name string, args []any) (result any, err err
 func ImportStringFuncs(ctx ExprContext) {
 	ctx.RegisterFunc("joinStr", newGolangFunctor(joinStrFunc), typeString, []ExprFuncParam{
 		newFuncParam(paramSeparator),
-		newFuncParamFlagDef(paramItem, pfOptional|pfRepeat, ""),
+		newFuncParamFlag(paramItem, pfRepeat),
 	})
 
 	ctx.RegisterFunc("subStr", newGolangFunctor(subStrFunc), typeString, []ExprFuncParam{
 		newFuncParam(paramSource),
-		newFuncParamFlagDef(paramStart, pfOptional, 0),
+		newFuncParamFlagDef(paramStart, pfOptional, int64(0)),
-		newFuncParamFlagDef(paramCount, pfOptional, -1),
+		newFuncParamFlagDef(paramCount, pfOptional, int64(-1)),
 	})
 
 	ctx.RegisterFunc("splitStr", newGolangFunctor(splitStrFunc), "list of "+typeString, []ExprFuncParam{
 		newFuncParam(paramSource),
 		newFuncParamFlagDef(paramSeparator, pfOptional, ""),
-		newFuncParamFlagDef(paramCount, pfOptional, -1),
+		newFuncParamFlagDef(paramCount, pfOptional, int64(-1)),
 	})
 
 	ctx.RegisterFunc("trimStr", newGolangFunctor(trimStrFunc), typeString, []ExprFuncParam{
@@ -206,12 +205,14 @@ func ImportStringFuncs(ctx ExprContext) {
 
 	ctx.RegisterFunc("startsWithStr", newGolangFunctor(startsWithStrFunc), typeBoolean, []ExprFuncParam{
 		newFuncParam(paramSource),
-		newFuncParamFlag(paramPrefix, pfRepeat),
+		newFuncParam(paramPrefix),
+		newFuncParamFlag("other "+paramPrefix, pfRepeat),
 	})
 
 	ctx.RegisterFunc("endsWithStr", newGolangFunctor(endsWithStrFunc), typeBoolean, []ExprFuncParam{
 		newFuncParam(paramSource),
-		newFuncParamFlag(paramSuffix, pfRepeat),
+		newFuncParam(paramSuffix),
+		newFuncParamFlag("other "+paramSuffix, pfRepeat),
 	})
 }
 

funcs_test.go

@@ -1,116 +0,0 @@
-// Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
-// All rights reserved.
-
-// funcs_test.go
-package expr
-
-import (
-	"errors"
-	"testing"
-)
-
-func TestFuncs(t *testing.T) {
-	inputs := []inputType{
-		/*   1 */ {`isNil(nil)`, true, nil},
-		/*   2 */ {`v=nil; isNil(v)`, true, nil},
-		/*   3 */ {`v=5; isNil(v)`, false, nil},
-		/*   4 */ {`int(true)`, int64(1), nil},
-		/*   5 */ {`int(false)`, int64(0), nil},
-		/*   6 */ {`int(3.1)`, int64(3), nil},
-		/*   7 */ {`int(3.9)`, int64(3), nil},
-		/*   8 */ {`int("432")`, int64(432), nil},
-		/*   9 */ {`int("1.5")`, nil, errors.New(`strconv.Atoi: parsing "1.5": invalid syntax`)},
-		/*  10 */ {`int("432", 4)`, nil, errors.New(`too much params -- expected 1, got 2`)},
-		/*  11 */ {`int(nil)`, nil, errors.New(`int() can't convert <nil> to int`)},
-		/*  12 */ {`two=func(){2}; two()`, int64(2), nil},
-		/*  13 */ {`double=func(x) {2*x}; (double(3))`, int64(6), nil},
-		/*  14 */ {`double=func(x){2*x}; double(3)`, int64(6), nil},
-		/*  15 */ {`double=func(x){2*x}; a=5; double(3+a) + 1`, int64(17), nil},
-		/*  16 */ {`double=func(x){2*x}; a=5; two=func() {2}; (double(3+a) + 1) * two()`, int64(34), nil},
-		/*  17 */ {`builtin "import"; import("./test-funcs.expr"); (double(3+a) + 1) * two()`, int64(34), nil},
-		/*  18 */ {`builtin "import"; import("test-funcs.expr"); (double(3+a) + 1) * two()`, int64(34), nil},
-		/*  19 */ {`@x="hello"; @x`, nil, errors.New(`[1:3] variable references are not allowed in top level expressions: "@x"`)},
-		/*  20 */ {`f=func(){@x="hello"}; f(); x`, "hello", nil},
-		/*  21 */ {`f=func(@y){@y=@y+1}; f(2); y`, int64(3), nil},
-		/*  22 */ {`f=func(@y){g=func(){@x=5}; @y=@y+g()}; f(2); y+x`, nil, errors.New(`undefined variable or function "x"`)},
-		/*  23 */ {`f=func(@y){g=func(){@x=5}; @z=g(); @y=@y+@z}; f(2); y+z`, int64(12), nil},
-		/*  24 */ {`f=func(@y){g=func(){@x=5}; g(); @z=x; @y=@y+@z}; f(2); y+z`, int64(12), nil},
-		/*  25 */ {`f=func(@y){g=func(){@x=5}; g(); @z=x; @x=@y+@z}; f(2); y+x`, int64(9), nil},
-		/*  26 */ {`builtin "import"; importAll("./test-funcs.expr"); six()`, int64(6), nil},
-		/*  27 */ {`builtin "import"; import("./sample-export-all.expr"); six()`, int64(6), nil},
-		/*  28 */ {`builtin "string"; joinStr("-", "one", "two", "three")`, "one-two-three", nil},
-		/*  29 */ {`builtin "string"; joinStr("-", ["one", "two", "three"])`, "one-two-three", nil},
-		/*  30 */ {`builtin "string"; ls= ["one", "two", "three"]; joinStr("-", ls)`, "one-two-three", nil},
-		/*  31 */ {`builtin "string"; ls= ["one", "two", "three"]; joinStr(1, ls)`, nil, errors.New(`joinStr() the "separator" parameter must be a string, got a int64 (1)`)},
-		/*  32 */ {`builtin "string"; ls= ["one", 2, "three"]; joinStr("-", ls)`, nil, errors.New(`joinStr() expected string, got int64 (2)`)},
-		/*  33 */ {`builtin "string"; "<"+trimStr("  bye bye  ")+">"`, "<bye bye>", nil},
-		/*  34 */ {`builtin "string"; subStr("0123456789", 1,2)`, "12", nil},
-		/*  35 */ {`builtin "string"; subStr("0123456789", -3,2)`, "78", nil},
-		/*  36 */ {`builtin "string"; subStr("0123456789", -3)`, "789", nil},
-		/*  37 */ {`builtin "string"; subStr("0123456789")`, "0123456789", nil},
-		/*  38 */ {`builtin "string"; startsWithStr("0123456789", "xyz", "012")`, true, nil},
-		/*  39 */ {`builtin "string"; startsWithStr("0123456789", "xyz", "0125")`, false, nil},
-		/*  40 */ {`builtin "string"; startsWithStr("0123456789")`, nil, errors.New(`too few params -- expected 2 or more, got 1`)},
-		/*  41 */ {`builtin "string"; endsWithStr("0123456789", "xyz", "789")`, true, nil},
-		/*  42 */ {`builtin "string"; endsWithStr("0123456789", "xyz", "0125")`, false, nil},
-		/*  43 */ {`builtin "string"; endsWithStr("0123456789")`, nil, errors.New(`too few params -- expected 2 or more, got 1`)},
-		/*  44 */ {`builtin "string"; splitStr("one-two-three", "-", )`, newListA("one", "two", "three"), nil},
-		/*  45 */ {`isInt(2+1)`, true, nil},
-		/*  46 */ {`isInt(3.1)`, false, nil},
-		/*  47 */ {`isFloat(3.1)`, true, nil},
-		/*  48 */ {`isString("3.1")`, true, nil},
-		/*  49 */ {`isString("3" + 1)`, true, nil},
-		/*  50 */ {`isList(["3",  1])`, true, nil},
-		/*  51 */ {`isDict({"a":"3",  "b":1})`, true, nil},
-		/*  52 */ {`isFract(1|3)`, true, nil},
-		/*  53 */ {`isFract(3|1)`, false, nil},
-		/*  54 */ {`isRational(3|1)`, true, nil},
-		/*  55 */ {`builtin "math.arith"; add(1,2)`, int64(3), nil},
-		/*  56 */ {`fract("2.2(3)")`, newFraction(67, 30), nil},
-		/*  57 */ {`fract("1.21(3)")`, newFraction(91, 75), nil},
-		/*  58 */ {`fract(1.21(3))`, newFraction(91, 75), nil},
-		/*  59 */ {`fract(1.21)`, newFraction(121, 100), nil},
-		/*  60 */ {`dec(2)`, float64(2), nil},
-		/*  61 */ {`dec(2.0)`, float64(2), nil},
-		/*  62 */ {`dec("2.0")`, float64(2), nil},
-		/*  63 */ {`dec(true)`, float64(1), nil},
-		/*  64 */ {`dec(true")`, nil, errors.New("[1:11] missing string termination \"")},
-		/*  65 */ {`builtin "string"; joinStr("-", [1, "two", "three"])`, nil, errors.New(`joinStr() expected string, got int64 (1)`)},
-		/*  66 */ {`dec()`, nil, errors.New(`too few params -- expected 1, got 0`)},
-		/*  67 */ {`dec(1,2,3)`, nil, errors.New(`too much params -- expected 1, got 3`)},
-		/*  68 */ {`builtin "string"; joinStr()`, nil, errors.New(`too few params -- expected 1 or more, got 0`)},
-		/*  69 */ /*{`builtin "string"; $$global`, `vars: {
-
-		}
-		funcs: {
-		    	add(any=0 ...) -> number,
-		    	dec(any) -> decimal,
-		    	endsWithStr(source, suffix) -> boolean,
-		    	fract(any, denominator=1) -> fraction,
-		    	import( ...) -> any,
-		    	importAll( ...) -> any,
-		    	int(any) -> integer,
-		    	isBool(any) -> boolean,
-		    	isDec(any) -> boolean,
-		    	isDict(any) -> boolean,
-		    	isFloat(any) -> boolean,
-		    	isFract(any) -> boolean,
-		    	isInt(any) -> boolean,
-		    	isList(any) -> boolean,
-		    	isNil(any) -> boolean,
-		    	isString(any) -> boolean,
-		    	joinStr(separator, item="" ...) -> string,
-		    	mul(any=1 ...) -> number,
-		    	splitStr(source, separator="", count=-1) -> list of string,
-		    	startsWithStr(source, prefix) -> boolean,
-		    	subStr(source, start=0, count=-1) -> string,
-		    	trimStr(source) -> string
-		}
-		`, nil},*/
-	}
-
-	t.Setenv("EXPR_PATH", ".")
-
-	// parserTestSpec(t, "Func", inputs, 69)
-	parserTest(t, "Func", inputs)
-}

function.go

@@ -26,6 +26,14 @@ func (functor *baseFunctor) ToString(opt FmtOpt) (s string) {
 	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
 }
@@ -34,7 +42,7 @@ func (functor *baseFunctor) GetFunc() ExprFunc {
 	return functor.info
 }
 
-// ---- Linking with the functions of Go
+// ---- Linking with Go functions
 type golangFunctor struct {
 	baseFunctor
 	f FuncTemplate
@@ -48,31 +56,39 @@ func (functor *golangFunctor) Invoke(ctx ExprContext, name string, args []any) (
 	return functor.f(ctx, name, args)
 }
 
-// ---- Linking with the functions of Expr
+// ---- Linking with Expr functions
 type exprFunctor struct {
 	baseFunctor
-	params []string
+	params []ExprFuncParam
 	expr   Expr
+	defCtx ExprContext
 }
 
-func newExprFunctor(e Expr, params []string) *exprFunctor {
+// func newExprFunctor(e Expr, params []string, ctx ExprContext) *exprFunctor {
-	return &exprFunctor{expr: e, params: params}
+// 	return &exprFunctor{expr: e, params: params, defCtx: ctx}
+// }
+
+func newExprFunctor(e Expr, params []ExprFuncParam, ctx ExprContext) *exprFunctor {
+	return &exprFunctor{expr: e, params: params, defCtx: ctx}
 }
 
 func (functor *exprFunctor) Invoke(ctx ExprContext, name string, args []any) (result any, err error) {
+	if functor.defCtx != nil {
+		ctx.Merge(functor.defCtx)
+	}
+
 	for i, p := range functor.params {
 		if i < len(args) {
 			arg := args[i]
 			if funcArg, ok := arg.(Functor); ok {
 				// ctx.RegisterFunc(p, functor, 0, -1)
-				ctx.RegisterFunc(p, funcArg, typeAny, []ExprFuncParam{
+				paramSpecs := funcArg.GetParams()
-					newFuncParam(paramValue),
+				ctx.RegisterFunc(p.Name(), funcArg, typeAny, paramSpecs)
-				})
 			} else {
-				ctx.UnsafeSetVar(p, arg)
+				ctx.UnsafeSetVar(p.Name(), arg)
 			}
 		} else {
-			ctx.UnsafeSetVar(p, nil)
+			ctx.UnsafeSetVar(p.Name(), nil)
 		}
 	}
 	result, err = functor.expr.eval(ctx, false)
@@ -152,6 +168,7 @@ func newFuncInfo(name string, functor Functor, returnType string, params []ExprF
 				return nil, fmt.Errorf("can't specify non-optional param after optional ones: %q", p.Name())
 			}
 			if p.IsRepeat() {
+				minArgs--
 				maxArgs = -1
 			}
 		}
@@ -205,7 +222,7 @@ func (info *funcInfo) ToString(opt FmtOpt) string {
 	if info.maxArgs < 0 {
 		sb.WriteString(" ...")
 	}
-	sb.WriteString("): ")
+	sb.WriteString("):")
 	if len(info.returnType) > 0 {
 		sb.WriteString(info.returnType)
 	} else {

global-context.go

@@ -40,11 +40,25 @@ func GetVar(ctx ExprContext, name string) (value any, exists bool) {
 	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)
+		}
+	}
+	return
+}
 func GetFuncInfo(ctx ExprContext, name string) (item ExprFunc, exists bool, ownerCtx ExprContext) {
-	if item, exists = ctx.GetFuncInfo(name); exists {
+	if len(name) > 0 {
-		ownerCtx = ctx
+		if item, exists = GetLocalFuncInfo(ctx, name); exists {
-	} else if item, exists = globalCtx.GetFuncInfo(name); exists {
+			ownerCtx = ctx
-		ownerCtx = globalCtx
+		} else if item, exists = globalCtx.GetFuncInfo(name); exists {
+			ownerCtx = globalCtx
+		}
 	}
 	return
 }

iter-list.go

@@ -106,10 +106,19 @@ func (it *ListIterator) CallOperation(name string, args []any) (v any, err error
 
 func (it *ListIterator) Current() (item any, err error) {
 	a := *(it.a)
-	if it.index >= 0 && it.index <= it.stop {
+	if it.start <= it.stop {
-		item = a[it.index]
+		if it.stop < len(a) && it.index >= it.start && it.index <= it.stop {
+			item = a[it.index]
+		} else {
+			err = io.EOF
+		}
 	} else {
-		err = io.EOF
+		if it.start < len(a) && it.index >= it.stop && it.index <= it.start {
+			item = a[it.index]
+		} else {
+			err = io.EOF
+		}
+
 	}
 	return
 }

iterator.go

@@ -34,7 +34,7 @@ type ExtIterator interface {
 }
 
 func errNoOperation(name string) error {
-	return fmt.Errorf("no %q function defined in the data-source", name)
+	return fmt.Errorf("no %s() function defined in the data-source", name)
 }
 
 func errInvalidDataSource() error {

list-type.go

@@ -0,0 +1,162 @@
+// Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
+// All rights reserved.
+
+// list-type.go
+package expr
+
+import (
+	"fmt"
+	"reflect"
+	"strings"
+)
+
+type ListType []any
+
+func newListA(listAny ...any) (list *ListType) {
+	if listAny == nil {
+		listAny = []any{}
+	}
+	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
+		}
+		list = &ls
+	}
+	return
+}
+
+func (ls *ListType) ToString(opt FmtOpt) (s string) {
+	var sb strings.Builder
+	sb.WriteByte('[')
+	if len(*ls) > 0 {
+		if opt&MultiLine != 0 {
+			sb.WriteString("\n  ")
+		}
+		for i, item := range []any(*ls) {
+			if i > 0 {
+				if opt&MultiLine != 0 {
+					sb.WriteString(",\n  ")
+				} else {
+					sb.WriteString(", ")
+				}
+			}
+			if s, ok := item.(string); ok {
+				sb.WriteByte('"')
+				sb.WriteString(s)
+				sb.WriteByte('"')
+			} else {
+				sb.WriteString(fmt.Sprintf("%v", item))
+			}
+		}
+		if opt&MultiLine != 0 {
+			sb.WriteByte('\n')
+		}
+	}
+	sb.WriteByte(']')
+	s = sb.String()
+	if opt&Truncate != 0 && len(s) > TruncateSize {
+		s = TruncateString(s)
+	}
+	return
+}
+
+func (ls *ListType) String() string {
+	return ls.ToString(0)
+}
+
+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) {
+	if len(*ls) >= len(*t) {
+		answer = true
+		for _, item := range *t {
+			if answer = ls.indexDeepSameCmp(item) >= 0; !answer {
+				break
+			}
+		}
+	}
+	return
+}
+
+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 {
+			break
+		} else if eq {
+			index = i
+			break
+		}
+	}
+	return
+}
+
+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 {
+				same = false
+				break
+			}
+		}
+	}
+	return
+}
+
+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)
+			}
+		} else {
+			var cmp int
+			if cmp, err = cmpAnyFract(a, b); err == nil {
+				eq = cmp == 0
+			}
+		}
+	} else if deepCmp != nil && IsList(a) && IsList(b) {
+		eq, err = deepCmp(a, b)
+	} else {
+		eq = reflect.DeepEqual(a, b)
+	}
+
+	return
+}
+
+func (list *ListType) setItem(index int64, value any) (err error) {
+	if index >= 0 && index < int64(len(*list)) {
+		(*list)[index] = value
+	} else {
+		err = fmt.Errorf("index %d out of bounds (0, %d)", index, len(*list)-1)
+	}
+	return
+}
+

module-register.go

@@ -30,31 +30,6 @@ func registerImport(name string, importFunc func(ExprContext), description strin
 	moduleRegister[name] = newModule(importFunc, description)
 }
 
-// func ImportInContext(ctx ExprContext, name string) (exists bool) {
-// 	var mod *module
-// 	if mod, exists = moduleRegister[name]; exists {
-// 		mod.importFunc(ctx)
-// 		mod.imported = true
-// 	}
-// 	return
-// }
-
-// func ImportInContextByGlobPattern(ctx ExprContext, pattern string) (count int, err error) {
-// 	var matched bool
-// 	for name, mod := range moduleRegister {
-// 		if matched, err = filepath.Match(pattern, name); err == nil {
-// 			if matched {
-// 				count++
-// 				mod.importFunc(ctx)
-// 				mod.imported = true
-// 			}
-// 		} else {
-// 			break
-// 		}
-// 	}
-// 	return
-// }
-
 func IterateModules(op func(name, description string, imported bool) bool) {
 	if op != nil {
 		for name, mod := range moduleRegister {

operand-dict.go

@@ -4,124 +4,6 @@
 // operand-dict.go
 package expr
 
-import (
-	"fmt"
-	"reflect"
-	"strings"
-)
-
-type DictType map[any]any
-
-func newDict(dictAny map[any]*term) (dict *DictType) {
-	var d DictType
-	if dictAny != nil {
-		d = make(DictType, len(dictAny))
-		for i, item := range dictAny {
-			d[i] = item
-		}
-	} else {
-		d = make(DictType)
-	}
-	dict = &d
-	return
-}
-
-func (dict *DictType) toMultiLine(sb *strings.Builder, indent int) {
-	sb.WriteString(strings.Repeat("\t", indent))
-	sb.WriteString("{\n")
-
-	first := true
-	for name, value := range *dict {
-		if first {
-			first = false
-		} else {
-			sb.WriteByte(',')
-			sb.WriteByte('\n')
-		}
-
-		sb.WriteString(strings.Repeat("\t", indent+1))
-		if key, ok := name.(string); ok {
-			sb.WriteString(string('"') + key + string('"'))
-		} else {
-			sb.WriteString(fmt.Sprintf("%v", name))
-		}
-		sb.WriteString(": ")
-		if f, ok := value.(Formatter); ok {
-			sb.WriteString(f.ToString(MultiLine))
-		} else if _, ok = value.(Functor); ok {
-			sb.WriteString("func(){}")
-		} else {
-			sb.WriteString(fmt.Sprintf("%v", value))
-		}
-	}
-	sb.WriteString(strings.Repeat("\t", indent))
-	sb.WriteString("\n}")
-}
-
-func (dict *DictType) ToString(opt FmtOpt) string {
-	var sb strings.Builder
-	if opt&MultiLine != 0 {
-		dict.toMultiLine(&sb, 0)
-	} else {
-		sb.WriteByte('{')
-		first := true
-		for key, value := range *dict {
-			if first {
-				first = false
-			} else {
-				sb.WriteString(", ")
-			}
-			if s, ok := key.(string); ok {
-				sb.WriteString(string('"') + s + string('"'))
-			} else {
-				sb.WriteString(fmt.Sprintf("%v", key))
-			}
-			sb.WriteString(": ")
-			if formatter, ok := value.(Formatter); ok {
-				sb.WriteString(formatter.ToString(opt))
-			} else if t, ok := value.(*term); ok {
-				sb.WriteString(t.String())
-			} else {
-				sb.WriteString(fmt.Sprintf("%#v", value))
-			}
-		}
-		sb.WriteByte('}')
-	}
-	return sb.String()
-}
-
-func (dict *DictType) String() string {
-	return dict.ToString(0)
-}
-
-func (dict *DictType) TypeName() string {
-	return "dict"
-}
-
-func (dict *DictType) hasKey(target any) (ok bool) {
-	for key := range *dict {
-		if ok = reflect.DeepEqual(key, target); ok {
-			break
-		}
-	}
-	return
-}
-
-func (dict *DictType) clone() (c *DictType) {
-	c = newDict(nil)
-	for k, v := range *dict {
-		(*c)[k] = v
-	}
-	return
-}
-
-func (dict *DictType) merge(second *DictType) {
-	if second != nil {
-		for k, v := range *second {
-			(*dict)[k] = v
-		}
-	}
-}
 
 // -------- dict term
 func newDictTerm(args map[any]*term) *term {

operand-func.go

@@ -22,16 +22,24 @@ func newFuncCallTerm(tk *Token, args []*term) *term {
 }
 
 // -------- eval func call
-func checkFunctionCall(ctx ExprContext, name string, params []any) (err error) {
+func checkFunctionCall(ctx ExprContext, name string, varParams *[]any) (err error) {
 	if info, exists, owner := GetFuncInfo(ctx, name); exists {
-		if info.MinArgs() > len(params) {
+		passedCount := len(*varParams)
-			err = errTooFewParams(info.MinArgs(), info.MaxArgs(), len(params))
+		if info.MinArgs() > passedCount {
+			err = errTooFewParams(name, info.MinArgs(), info.MaxArgs(), passedCount)
 		}
-		if err == nil && info.MaxArgs() >= 0 && info.MaxArgs() < len(params) {
+		for i, p := range info.Params() {
-			err = errTooMuchParams(info.MaxArgs(), len(params))
+			if i >= passedCount {
+				if !p.IsOptional() {
+					break
+				}
+				*varParams = append(*varParams, p.DefaultValue())
+			}
+		}
+		if err == nil && info.MaxArgs() >= 0 && info.MaxArgs() < len(*varParams) {
+			err = errTooMuchParams(name, info.MaxArgs(), len(*varParams))
 		}
 		if err == nil && owner != ctx {
-			// ctx.RegisterFunc(name, info.Functor(), info.MinArgs(), info.MaxArgs())
 			ctx.RegisterFuncInfo(info)
 		}
 	} else {
@@ -43,8 +51,7 @@ func checkFunctionCall(ctx ExprContext, name string, params []any) (err error) {
 func evalFuncCall(parentCtx ExprContext, self *term) (v any, err error) {
 	ctx := cloneContext(parentCtx)
 	name, _ := self.tk.Value.(string)
-	// fmt.Printf("Call %s(), context: %p\n", name, ctx)
+	params := make([]any, len(self.children), len(self.children)+5)
-	params := make([]any, len(self.children))
 	for i, tree := range self.children {
 		var param any
 		if param, err = tree.compute(ctx); err != nil {
@@ -52,8 +59,9 @@ func evalFuncCall(parentCtx ExprContext, self *term) (v any, err error) {
 		}
 		params[i] = param
 	}
+
 	if err == nil {
-		if err = checkFunctionCall(ctx, name, params); err == nil {
+		if err = checkFunctionCall(ctx, name, &params); err == nil {
 			if v, err = ctx.Call(name, params); err == nil {
 				exportObjects(parentCtx, ctx)
 			}
@@ -75,44 +83,23 @@ func newFuncDefTerm(tk *Token, args []*term) *term {
 }
 
 // -------- eval func def
-// TODO
-// type funcDefFunctor struct {
-// 	params []string
-// 	expr   Expr
-// }
-
-// func (funcDef *funcDefFunctor) Invoke(ctx ExprContext, name string, args []any) (result any, err error) {
-// 	for i, p := range funcDef.params {
-// 		if i < len(args) {
-// 			arg := args[i]
-// 			if functor, ok := arg.(Functor); ok {
-// 				// ctx.RegisterFunc(p, functor, 0, -1)
-// 				ctx.RegisterFunc2(p, functor, typeAny, []ExprFuncParam{
-// 					newFuncParam(paramValue),
-// 				})
-// 			} else {
-// 				ctx.UnsafeSetVar(p, arg)
-// 			}
-// 		} else {
-// 			ctx.UnsafeSetVar(p, nil)
-// 		}
-// 	}
-// 	result, err = funcDef.expr.eval(ctx, false)
-// 	return
-// }
-
 func evalFuncDef(ctx ExprContext, self *term) (v any, err error) {
 	bodySpec := self.value()
 	if expr, ok := bodySpec.(*ast); ok {
-		paramList := make([]string, 0, len(self.children))
+		paramList := make([]ExprFuncParam, 0, len(self.children))
 		for _, param := range self.children {
-			paramList = append(paramList, param.source())
+			var defValue any
+			flags := paramFlags(0)
+			if len(param.children) > 0 {
+				flags |= pfOptional
+				if defValue, err = param.children[0].compute(ctx); err != nil {
+					return
+				}
+			}
+			info := newFuncParamFlagDef(param.source(), flags, defValue)
+			paramList = append(paramList, info)
 		}
-		v = newExprFunctor(expr, paramList)
+		v = newExprFunctor(expr, paramList, ctx)
-		// v = &funcDefFunctor{
-		// 	params: paramList,
-		// 	expr:   expr,
-		// }
 	} else {
 		err = errors.New("invalid function definition: the body specification must be an expression")
 	}

operand-iterator.go

@@ -148,23 +148,6 @@ func evalIterator(ctx ExprContext, self *term) (v any, err error) {
 	return
 }
 
-// func evalChildren(ctx ExprContext, terms []*term, firstChildValue any) (list *ListType, err error) {
-// 	items := make(ListType, len(terms))
-// 	for i, tree := range terms {
-// 		var param any
-// 		if i == 0 && firstChildValue != nil {
-// 			param = firstChildValue
-// 		} else if param, err = tree.compute(ctx); err != nil {
-// 			break
-// 		}
-// 		items[i] = param
-// 	}
-// 	if err == nil {
-// 		list = &items
-// 	}
-// 	return
-// }
-
 func evalSibling(ctx ExprContext, terms []*term, firstChildValue any) (list []any, err error) {
 	items := make([]any, 0, len(terms))
 	for i, tree := range terms {

operand-list.go

@@ -4,91 +4,14 @@
 // operand-list.go
 package expr
 
-import (
-	"fmt"
-	"reflect"
-	"strings"
-)
-
-type ListType []any
-
-func newListA(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
-		}
-		list = &ls
-	}
-	return
-}
-
-func (ls *ListType) ToString(opt FmtOpt) (s string) {
-	var sb strings.Builder
-	sb.WriteByte('[')
-	if len(*ls) > 0 {
-		if opt&MultiLine != 0 {
-			sb.WriteString("\n  ")
-		}
-		for i, item := range []any(*ls) {
-			if i > 0 {
-				if opt&MultiLine != 0 {
-					sb.WriteString(",\n  ")
-				} else {
-					sb.WriteString(", ")
-				}
-			}
-			if s, ok := item.(string); ok {
-				sb.WriteByte('"')
-				sb.WriteString(s)
-				sb.WriteByte('"')
-			} else {
-				sb.WriteString(fmt.Sprintf("%v", item))
-			}
-		}
-		if opt&MultiLine != 0 {
-			sb.WriteByte('\n')
-		}
-	}
-	sb.WriteByte(']')
-	s = sb.String()
-	if opt&Truncate != 0 && len(s) > TruncateSize {
-		s = TruncateString(s)
-	}
-	return
-}
-
-func (ls *ListType) String() string {
-	return ls.ToString(0)
-}
-
-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
-}
-
 // -------- list term
 func newListTermA(args ...*term) *term {
-	return newListTerm(args)
+	return newListTerm(0, 0, args)
 }
 
-func newListTerm(args []*term) *term {
+func newListTerm(row, col int, args []*term) *term {
 	return &term{
-		tk:       *NewValueToken(0, 0, SymList, "[]", args),
+		tk:       *NewValueToken(row, col, SymList, "[]", args),
 		parent:   nil,
 		children: nil,
 		position: posLeaf,

operand-var.go

@@ -9,9 +9,7 @@ import "fmt"
 // -------- variable term
 func newVarTerm(tk *Token) *term {
 	t := &term{
-		tk: *tk,
+		tk:       *tk,
-		// class:    classVar,
-		// kind:     kindUnknown,
 		parent:   nil,
 		children: nil,
 		position: posLeaf,

operator-assign.go

@@ -16,14 +16,59 @@ func newAssignTerm(tk *Token) (inst *term) {
 	}
 }
 
+func assignCollectionItem(ctx ExprContext, collectionTerm, keyListTerm *term, value any) (err error) {
+	var collectionValue, keyListValue, keyValue any
+	var keyList *ListType
+	var ok bool
+
+	if collectionValue, err = collectionTerm.compute(ctx); err != nil {
+		return
+	}
+
+	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))
+		return
+	}
+	if keyValue = (*keyList)[0]; keyValue == nil {
+		err = keyListTerm.Errorf("index/key is nil")
+		return
+	}
+
+	switch collection := collectionValue.(type) {
+	case *ListType:
+		if index, ok := keyValue.(int64); ok {
+			err = collection.setItem(index, value)
+		} else {
+			err = keyListTerm.Errorf("integer expected, got %v [%s]", keyValue, typeName(keyValue))
+		}
+	case *DictType:
+		err = collection.setItem(keyValue, value)
+	default:
+		err = collectionTerm.Errorf("collection expected")
+	}
+	return
+}
+
+func assignValue(ctx 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)
+	}
+	return
+}
+
 func evalAssign(ctx ExprContext, self *term) (v any, err error) {
 	if err = self.checkOperands(); err != nil {
 		return
 	}
 
 	leftTerm := self.children[0]
-	if leftTerm.tk.Sym != SymVariable {
+	leftSym := leftTerm.symbol()
-		err = leftTerm.tk.Errorf("left operand of %q must be a variable", self.tk.source)
+	if leftSym != SymVariable && leftSym != SymIndex {
+		err = leftTerm.tk.Errorf("left operand of %q must be a variable or a collection's item", self.tk.source)
 		return
 	}
 
@@ -31,25 +76,22 @@ func evalAssign(ctx ExprContext, self *term) (v any, err error) {
 
 	if v, err = rightChild.compute(ctx); err == nil {
 		if functor, ok := v.(Functor); ok {
-			funcName := rightChild.source()
+			if info := functor.GetFunc(); info != nil {
-			if info, exists, _ := GetFuncInfo(ctx, funcName); exists {
-				// ctx.RegisterFuncInfo(info)
 				ctx.RegisterFunc(leftTerm.source(), info.Functor(), info.ReturnType(), info.Params())
 			} else if funcDef, ok := functor.(*exprFunctor); ok {
-				paramSpecs := ForAll(funcDef.params, newFuncParam)
+				paramSpecs := ForAll(funcDef.params, func(p ExprFuncParam) ExprFuncParam { return p })
-				// paramCount := len(funcDef.params)
+
-				// paramSpecs := make([]ExprFuncParam, paramCount)
-				// for i := range paramSpecs {
-				// 	paramSpecs[i] = newFuncParam(funcDef.params[i])
-				// }
 				ctx.RegisterFunc(leftTerm.source(), functor, typeAny, paramSpecs)
 			} else {
-				err = self.Errorf("unknown function %s()", funcName)
+				err = self.Errorf("unknown function %s()", rightChild.source())
 			}
 		} else {
-			ctx.UnsafeSetVar(leftTerm.source(), v)
+			err = assignValue(ctx, leftTerm, v)
 		}
 	}
+	if err != nil {
+		v = nil
+	}
 	return
 }
 

operator-dot.go

@@ -4,8 +4,6 @@
 // operator-dot.go
 package expr
 
-import "fmt"
-
 // -------- dot term
 func newDotTerm(tk *Token) (inst *term) {
 	return &term{
@@ -17,24 +15,6 @@ func newDotTerm(tk *Token) (inst *term) {
 	}
 }
 
-func verifyIndex(ctx ExprContext, indexTerm *term, maxValue int) (index int, err error) {
-	var v int
-	var indexValue any
-	if indexValue, err = indexTerm.compute(ctx); err == nil {
-		if v, err = indexTerm.toInt(indexValue, "index expression value must be integer"); err == nil {
-			if v < 0 && v >= -maxValue {
-				v = maxValue + v
-			}
-			if v >= 0 && v < maxValue {
-				index = v
-			} else {
-				err = indexTerm.Errorf("index %d out of bounds", v)
-			}
-		}
-	}
-	return
-}
-
 func evalDot(ctx ExprContext, self *term) (v any, err error) {
 	var leftValue, rightValue any
 
@@ -48,27 +28,8 @@ func evalDot(ctx ExprContext, self *term) (v any, err error) {
 	indexTerm := self.children[1]
 
 	switch unboxedValue := leftValue.(type) {
-	case *ListType:
-		var index int
-		array := ([]any)(*unboxedValue)
-		if index, err = verifyIndex(ctx, indexTerm, len(array)); err == nil {
-			v = array[index]
-		}
-	case string:
-		var index int
-		if index, err = verifyIndex(ctx, indexTerm, len(unboxedValue)); err == nil {
-			v = string(unboxedValue[index])
-		}
-	case *DictType:
-		var ok bool
-		var indexValue any
-		if indexValue, err = indexTerm.compute(ctx); err == nil {
-			if v, ok = (*unboxedValue)[indexValue]; !ok {
-				err = fmt.Errorf("key %v does not belong to the dictionary", rightValue)
-			}
-		}
 	case ExtIterator:
-		if indexTerm.symbol() == SymVariable {
+		if indexTerm.symbol() == SymVariable /*|| indexTerm.symbol() == SymString */ {
 			opName := indexTerm.source()
 			if unboxedValue.HasOperation(opName) {
 				v, err = unboxedValue.CallOperation(opName, []any{})
@@ -76,9 +37,13 @@ func evalDot(ctx ExprContext, self *term) (v any, err error) {
 				err = indexTerm.Errorf("this iterator do not support the %q command", opName)
 				v = false
 			}
+		} else {
+			err = indexTerm.tk.ErrorExpectedGot("identifier")
 		}
 	default:
-		err = self.errIncompatibleTypes(leftValue, rightValue)
+		if rightValue, err = self.children[1].compute(ctx); err == nil {
+			err = self.errIncompatibleTypes(leftValue, rightValue)
+		}
 	}
 	return
 }

operator-fraction.go

@@ -9,205 +9,8 @@ package expr
 import (
 	"errors"
 	"fmt"
-	"math"
-	"strconv"
-	"strings"
 )
 
-type fraction struct {
-	num, den int64
-}
-
-func newFraction(num, den int64) *fraction {
-	/*	if den < 0 {
-		den = -den
-		num = -num
-	}*/
-	num, den = simplifyIntegers(num, den)
-	return &fraction{num, den}
-}
-
-func float64ToFraction(f float64) (fract *fraction, err error) {
-	var sign string
-	intPart, decPart := math.Modf(f)
-	if decPart < 0.0 {
-		sign = "-"
-		intPart = -intPart
-		decPart = -decPart
-	}
-	dec := fmt.Sprintf("%.12f", decPart)
-	s := fmt.Sprintf("%s%.f%s", sign, intPart, dec[1:])
-	// fmt.Printf("S: '%s'\n",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 _float64ToFraction(f float64) (num, den int64, err error) {
-	const expMask = 1<<11 - 1
-	bits := math.Float64bits(f)
-	mantissa := bits & (1<<52 - 1)
-	exp := int((bits >> 52) & expMask)
-	switch exp {
-	case expMask: // non-finite
-		err = errors.New("infite")
-		return
-	case 0: // denormal
-		exp -= 1022
-	default: // normal
-		mantissa |= 1 << 52
-		exp -= 1023
-	}
-
-	shift := 52 - exp
-
-	// Optimization (?): partially pre-normalise.
-	for mantissa&1 == 0 && shift > 0 {
-		mantissa >>= 1
-		shift--
-	}
-
-	if f < 0 {
-		num = -int64(mantissa)
-	} else {
-		num = int64(mantissa)
-	}
-	den = int64(1)
-
-	if shift > 0 {
-		den = den << shift
-	} else {
-		num = num << (-shift)
-	}
-	return
-}
-*/
-
-func makeGeneratingFraction(s string) (f *fraction, err error) {
-	var num, den int64
-	var sign int64 = 1
-	var parts []string
-	if len(s) == 0 {
-		goto exit
-	}
-	if s[0] == '-' {
-		sign = int64(-1)
-		s = s[1:]
-	} else if s[0] == '+' {
-		s = s[1:]
-	}
-	if strings.HasSuffix(s, "()") {
-		s = s[0 : len(s)-2]
-	}
-	parts = strings.SplitN(s, ".", 2)
-	if num, err = strconv.ParseInt(parts[0], 10, 64); err != nil {
-		return
-	}
-	if len(parts) == 1 {
-		f = newFraction(sign*num, 1)
-	} else if len(parts) == 2 {
-		subParts := strings.SplitN(parts[1], "(", 2)
-		if len(subParts) == 1 {
-			den = 1
-			dec := parts[1]
-			lsd := len(dec)
-			for i := lsd - 1; i >= 0 && dec[i] == '0'; i-- {
-				lsd--
-			}
-			for _, c := range dec[0:lsd] {
-				if c < '0' || c > '9' {
-					return nil, errExpectedGot("fract", "digit", c)
-				}
-				num = num*10 + int64(c-'0')
-				den = den * 10
-			}
-			f = newFraction(sign*num, den)
-		} else if len(subParts) == 2 {
-			sub := num
-			mul := int64(1)
-			for _, c := range subParts[0] {
-				if c < '0' || c > '9' {
-					return nil, errExpectedGot("fract", "digit", c)
-				}
-				num = num*10 + int64(c-'0')
-				sub = sub*10 + int64(c-'0')
-				mul *= 10
-			}
-			if len(subParts) == 2 {
-				if s[len(s)-1] != ')' {
-					goto exit
-				}
-				p := subParts[1][0 : len(subParts[1])-1]
-				for _, c := range p {
-					if c < '0' || c > '9' {
-						return nil, errExpectedGot("fract", "digit", c)
-					}
-					num = num*10 + int64(c-'0')
-					den = den*10 + 9
-				}
-				den *= mul
-			}
-			num -= sub
-			f = newFraction(sign*num, den)
-		}
-	}
-exit:
-	if f == nil {
-		err = errors.New("bad syntax")
-	}
-	return
-}
-
-func (f *fraction) toFloat() float64 {
-	return float64(f.num) / float64(f.den)
-}
-
-func (f *fraction) String() string {
-	return f.ToString(0)
-}
-
-func (f *fraction) ToString(opt FmtOpt) string {
-	var sb strings.Builder
-	if opt&MultiLine == 0 {
-		sb.WriteString(fmt.Sprintf("%d|%d", f.num, f.den))
-	} else {
-		var s, num string
-		if f.num < 0 && opt&TTY == 0 {
-			num = strconv.FormatInt(-f.num, 10)
-			s = "-"
-		} else {
-			num = strconv.FormatInt(f.num, 10)
-		}
-		den := strconv.FormatInt(f.den, 10)
-		size := max(len(num), len(den))
-		if opt&TTY != 0 {
-			sb.WriteString(fmt.Sprintf("\x1b[4m%[1]*s\x1b[0m\n", -size, fmt.Sprintf("%[1]*s", (size+len(num))/2, s+num)))
-		} else {
-			if len(s) > 0 {
-				sb.WriteString("  ")
-			}
-			sb.WriteString(fmt.Sprintf("%[1]*s", -size, fmt.Sprintf("%[1]*s", (size+len(num))/2, num)))
-			sb.WriteByte('\n')
-			if len(s) > 0 {
-				sb.WriteString(s)
-				sb.WriteByte(' ')
-			}
-			sb.WriteString(strings.Repeat("-", size))
-			sb.WriteByte('\n')
-			if len(s) > 0 {
-				sb.WriteString("  ")
-			}
-		}
-		sb.WriteString(fmt.Sprintf("%[1]*s", -size, fmt.Sprintf("%[1]*s", (size+len(den))/2, den)))
-	}
-
-	return sb.String()
-}
-
-func (f *fraction) TypeName() string {
-	return "fraction"
-}
-
 // -------- fraction term
 func newFractionTerm(tk *Token) *term {
 	return &term{
@@ -252,168 +55,11 @@ func evalFraction(ctx ExprContext, self *term) (v any, err error) {
 	if den == 1 {
 		v = num
 	} else {
-		v = &fraction{num, den}
+		v = &FractionType{num, den}
 	}
 	return
 }
 
-func gcd(a, b int64) (g int64) {
-	if a < 0 {
-		a = -a
-	}
-	if b < 0 {
-		b = -b
-	}
-	if a < b {
-		a, b = b, a
-	}
-	r := a % b
-	for r > 0 {
-		a, b = b, r
-		r = a % b
-	}
-	g = b
-	return
-}
-
-func lcm(a, b int64) (l int64) {
-	g := gcd(a, b)
-	l = a * b / g
-	return
-}
-
-func sumFract(f1, f2 *fraction) (sum *fraction) {
-	m := lcm(f1.den, f2.den)
-	sum = newFraction(f1.num*(m/f1.den)+f2.num*(m/f2.den), m)
-	return
-}
-
-func mulFract(f1, f2 *fraction) (prod *fraction) {
-	prod = newFraction(f1.num*f2.num, f1.den*f2.den)
-	return
-}
-
-func anyToFract(v any) (f *fraction, err error) {
-	var ok bool
-	if f, ok = v.(*fraction); !ok {
-		if n, ok := v.(int64); ok {
-			f = intToFraction(n)
-		}
-	}
-	if f == nil {
-		err = errExpectedGot("fract", typeFraction, v)
-	}
-	return
-}
-
-func anyPairToFract(v1, v2 any) (f1, f2 *fraction, err error) {
-	if f1, err = anyToFract(v1); err != nil {
-		return
-	}
-	if f2, err = anyToFract(v2); err != nil {
-		return
-	}
-	return
-}
-
-func sumAnyFract(af1, af2 any) (sum any, err error) {
-	var f1, f2 *fraction
-	if f1, f2, err = anyPairToFract(af1, af2); err != nil {
-		return
-	}
-	f := sumFract(f1, f2)
-	if f.num == 0 {
-		sum = 0
-	} else {
-		sum = simplifyFraction(f)
-	}
-	return
-}
-
-func subAnyFract(af1, af2 any) (sum any, err error) {
-	var f1, f2 *fraction
-	if f1, f2, err = anyPairToFract(af1, af2); err != nil {
-		return
-	}
-	f2.num = -f2.num
-	f := sumFract(f1, f2)
-	if f.num == 0 {
-		sum = 0
-	} else {
-		sum = simplifyFraction(f)
-	}
-	return
-}
-
-func mulAnyFract(af1, af2 any) (prod any, err error) {
-	var f1, f2 *fraction
-	if f1, f2, err = anyPairToFract(af1, af2); err != nil {
-		return
-	}
-	if f1.num == 0 || f2.num == 0 {
-		prod = 0
-	} else {
-		f := &fraction{f1.num * f2.num, f1.den * f2.den}
-		prod = simplifyFraction(f)
-	}
-	return
-}
-
-func divAnyFract(af1, af2 any) (quot any, err error) {
-	var f1, f2 *fraction
-	if f1, f2, err = anyPairToFract(af1, af2); err != nil {
-		return
-	}
-	if f2.num == 0 {
-		err = errors.New("division by zero")
-		return
-		return
-	}
-	if f1.num == 0 || f2.den == 0 {
-		quot = 0
-	} else {
-		f := &fraction{f1.num * f2.den, f1.den * f2.num}
-		quot = simplifyFraction(f)
-	}
-	return
-}
-
-func simplifyFraction(f *fraction) (v any) {
-	f.num, f.den = simplifyIntegers(f.num, f.den)
-	if f.den == 1 {
-		v = f.num
-	} else {
-		v = &fraction{f.num, f.den}
-	}
-	return v
-}
-
-func simplifyIntegers(num, den int64) (a, b int64) {
-	if num == 0 {
-		return 0, 1
-	}
-	if den == 0 {
-		panic("fraction with denominator == 0")
-	}
-	if den < 0 {
-		den = -den
-		num = -num
-	}
-	g := gcd(num, den)
-	a = num / g
-	b = den / g
-	return
-}
-
-func intToFraction(n int64) *fraction {
-	return &fraction{n, 1}
-}
-
-func isFraction(v any) (ok bool) {
-	_, ok = v.(*fraction)
-	return ok
-}
-
 // init
 func init() {
 	registerTermConstructor(SymVertBar, newFractionTerm)

operator-in.go

@@ -30,7 +30,7 @@ func evalIn(ctx ExprContext, self *term) (v any, err error) {
 
 	if IsList(rightValue) {
 		list, _ := rightValue.(*ListType)
-		v = list.indexDeepCmp(leftValue) >= 0
+		v = list.indexDeepSameCmp(leftValue) >= 0
 	} else if IsDict(rightValue) {
 		dict, _ := rightValue.(*DictType)
 		v = dict.hasKey(leftValue)

operator-index.go

@@ -0,0 +1,123 @@
+// Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
+// All rights reserved.
+
+// operator-index.go
+package expr
+
+// -------- index term
+func newIndexTerm(tk *Token) (inst *term) {
+	return &term{
+		tk:       *tk,
+		children: make([]*term, 0, 2),
+		position: posInfix,
+		priority: priDot,
+		evalFunc: evalIndex,
+	}
+}
+
+func verifyKey(indexTerm *term, indexList *ListType) (index any, err error) {
+	index = (*indexList)[0]
+	return
+}
+
+func verifyIndex(indexTerm *term, indexList *ListType, maxValue int) (index int, err error) {
+	var v int
+
+	if v, err = toInt((*indexList)[0], "index expression"); err == nil {
+		if v < 0 && v >= -maxValue {
+			v = maxValue + v
+		}
+		if v >= 0 && v < maxValue {
+			index = v
+		} else {
+			err = indexTerm.Errorf("index %d out of bounds", v)
+		}
+	}
+	return
+}
+
+func verifyRange(indexTerm *term, indexList *ListType, maxValue int) (startIndex, endIndex int, err error) {
+	v, _ := ((*indexList)[0]).(*intPair)
+	startIndex = v.a
+	endIndex = v.b
+	if startIndex < 0 && startIndex >= -maxValue {
+		startIndex = maxValue + startIndex
+	}
+	if endIndex < 0 && endIndex >= -maxValue {
+		endIndex = maxValue + endIndex + 1
+	}
+	if startIndex < 0 || startIndex > maxValue {
+		err = indexTerm.Errorf("range start-index %d is out of bounds", startIndex)
+	} else if endIndex < 0 || endIndex > maxValue {
+		err = indexTerm.Errorf("range end-index %d is out of bounds", endIndex)
+	} else if startIndex > endIndex {
+		err = indexTerm.Errorf("range start-index %d must not be greater than end-index %d", startIndex, endIndex)
+	}
+	return
+}
+
+func evalIndex(ctx ExprContext, self *term) (v any, err error) {
+	var leftValue, rightValue any
+	var indexList *ListType
+	var ok bool
+
+	if leftValue, rightValue, err = self.evalInfix(ctx); err != nil {
+		return
+	}
+
+	indexTerm := self.children[1]
+	if indexList, ok = rightValue.(*ListType); !ok {
+		err = self.Errorf("invalid index expression")
+		return
+	} else if len(*indexList) != 1 {
+		err = indexTerm.Errorf("one index only is allowed")
+		return
+	}
+
+	if IsInteger((*indexList)[0]) {
+		switch unboxedValue := leftValue.(type) {
+		case *ListType:
+			var index int
+			if index, err = verifyIndex(indexTerm, indexList, len(*unboxedValue)); err == nil {
+				v = (*unboxedValue)[index]
+			}
+		case string:
+			var index int
+			if index, err = verifyIndex(indexTerm, indexList, len(unboxedValue)); err == nil {
+				v = string(unboxedValue[index])
+			}
+		case *DictType:
+			var ok bool
+			var indexValue any
+			if indexValue, err = verifyKey(indexTerm, indexList); err == nil {
+				if v, ok = (*unboxedValue)[indexValue]; !ok {
+					err = indexTerm.Errorf("key %v does not belong to the dictionary", rightValue)
+				}
+			}
+		default:
+			err = self.errIncompatibleTypes(leftValue, rightValue)
+		}
+	} else if isIntPair((*indexList)[0]) {
+		switch unboxedValue := leftValue.(type) {
+		case *ListType:
+			var start, end int
+			if start, end, err = verifyRange(indexTerm, indexList, len(*unboxedValue)); err == nil {
+				sublist := ListType((*unboxedValue)[start:end])
+				v = &sublist
+			}
+		case string:
+			var start, end int
+			if start, end, err = verifyRange(indexTerm, indexList, len(unboxedValue)); err == nil {
+				v = unboxedValue[start:end]
+			}
+		default:
+			err = self.errIncompatibleTypes(leftValue, rightValue)
+		}
+	}
+	return
+}
+
+// init
+func init() {
+	registerTermConstructor(SymIndex, newIndexTerm)
+}

operator-range.go

@@ -0,0 +1,69 @@
+// Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
+// All rights reserved.
+
+// operator-range.go
+package expr
+
+import "fmt"
+
+// -------- range term
+type intPair struct {
+	a, b int
+}
+
+func (p *intPair) TypeName() string {
+	return typePair
+}
+
+func (p *intPair) ToString(opt FmtOpt) string {
+	return fmt.Sprintf("(%d, %d)", p.a, p.b)
+}
+
+func isIntPair(v any) bool {
+	_, ok := v.(*intPair)
+	return ok
+}
+
+func newRangeTerm(tk *Token) (inst *term) {
+	return &term{
+		tk:       *tk,
+		children: make([]*term, 0, 2),
+		position: posInfix,
+		priority: priDot,
+		evalFunc: evalRange,
+	}
+}
+
+func evalRange(ctx ExprContext, self *term) (v any, err error) {
+	var leftValue, rightValue any
+
+	// if err = self.checkOperands(); err != nil {
+	// 	return
+	// }
+	if len(self.children) == 0 {
+		leftValue = int64(0)
+		rightValue = int64(-1)
+	} else if len(self.children) == 1 {
+		if leftValue, err = self.children[0].compute(ctx); err != nil {
+			return
+		}
+		rightValue = int64(-1)
+	} else if leftValue, rightValue, err = self.evalInfix(ctx); err != nil {
+		return
+	}
+	if !(IsInteger(leftValue) && IsInteger(rightValue)) {
+		err = self.errIncompatibleTypes(leftValue, rightValue)
+		return
+	}
+
+	startIndex, _ := leftValue.(int64)
+	endIndex, _ := rightValue.(int64)
+
+	v = &intPair{int(startIndex), int(endIndex)}
+	return
+}
+
+// init
+func init() {
+	registerTermConstructor(SymColon, newRangeTerm)
+}

operator-rel.go

@@ -4,13 +4,13 @@
 // operator-rel.go
 package expr
 
+import "reflect"
+
 //-------- equal term
 
 func newEqualTerm(tk *Token) (inst *term) {
 	return &term{
-		tk: *tk,
+		tk:       *tk,
-		// class:    classOperator,
-		// kind:     kindBool,
 		children: make([]*term, 0, 2),
 		position: posInfix,
 		priority: priRelational,
@@ -18,6 +18,33 @@ func newEqualTerm(tk *Token) (inst *term) {
 	}
 }
 
+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) {
+				li, _ := a.(int64)
+				ri, _ := b.(int64)
+				eq = li == ri
+			} else {
+				eq = numAsFloat(a) == numAsFloat(b)
+			}
+		} else {
+			var cmp int
+			if cmp, err = cmpAnyFract(a, b); err == nil {
+				eq = cmp == 0
+			}
+		}
+	} else if deepCmp != nil && IsList(a) && IsList(b) {
+		eq, err = deepCmp(a, b)
+	} else {
+		eq = reflect.DeepEqual(a, b)
+	}
+
+	return
+}
+
 func evalEqual(ctx ExprContext, self *term) (v any, err error) {
 	var leftValue, rightValue any
 
@@ -25,21 +52,7 @@ func evalEqual(ctx ExprContext, self *term) (v any, err error) {
 		return
 	}
 
-	if IsNumber(leftValue) && IsNumber(rightValue) {
+	v, err = equals(leftValue, rightValue, nil)
-		if IsInteger(leftValue) && IsInteger(rightValue) {
-			li, _ := leftValue.(int64)
-			ri, _ := rightValue.(int64)
-			v = li == ri
-		} else {
-			v = numAsFloat(leftValue) == numAsFloat(rightValue)
-		}
-	} else if IsString(leftValue) && IsString(rightValue) {
-		ls, _ := leftValue.(string)
-		rs, _ := rightValue.(string)
-		v = ls == rs
-	} else {
-		err = self.errIncompatibleTypes(leftValue, rightValue)
-	}
 	return
 }
 
@@ -47,9 +60,7 @@ func evalEqual(ctx ExprContext, self *term) (v any, err error) {
 
 func newNotEqualTerm(tk *Token) (inst *term) {
 	return &term{
-		tk: *tk,
+		tk:       *tk,
-		// class:    classOperator,
-		// kind:     kindBool,
 		children: make([]*term, 0, 2),
 		position: posInfix,
 		priority: priRelational,
@@ -65,38 +76,11 @@ func evalNotEqual(ctx ExprContext, self *term) (v any, err error) {
 	return
 }
 
-// func evalNotEqual(ctx exprContext, self *term) (v any, err error) {
-// 	var leftValue, rightValue any
-
-// 	if leftValue, rightValue, err = self.evalInfix(ctx); err != nil {
-// 		return
-// 	}
-
-// 	if isNumber(leftValue) && isNumber(rightValue) {
-// 		if isInteger(leftValue) && isInteger(rightValue) {
-// 			li, _ := leftValue.(int64)
-// 			ri, _ := rightValue.(int64)
-// 			v = li != ri
-// 		} else {
-// 			v = numAsFloat(leftValue) != numAsFloat(rightValue)
-// 		}
-// 	} else if isString(leftValue) && isString(rightValue) {
-// 		ls, _ := leftValue.(string)
-// 		rs, _ := rightValue.(string)
-// 		v = ls != rs
-// 	} else {
-// 		err = self.errIncompatibleTypes(leftValue, rightValue)
-// 	}
-// 	return
-// }
-
 //-------- less term
 
 func newLessTerm(tk *Token) (inst *term) {
 	return &term{
-		tk: *tk,
+		tk:       *tk,
-		// class:    classOperator,
-		// kind:     kindBool,
 		children: make([]*term, 0, 2),
 		position: posInfix,
 		priority: priRelational,
@@ -104,28 +88,44 @@ 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) {
+				li, _ := a.(int64)
+				ri, _ := b.(int64)
+				isLess = li < ri
+			} else {
+				isLess = numAsFloat(a) < numAsFloat(b)
+			}
+		} else {
+			var cmp int
+			if cmp, err = cmpAnyFract(a, b); err == nil {
+				isLess = cmp < 0
+			}
+		}
+	} else if IsString(a) && 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 {
+		err = self.errIncompatibleTypes(a, b)
+	}
+	return
+}
+
 func evalLess(ctx ExprContext, self *term) (v any, err error) {
 	var leftValue, rightValue any
 
 	if leftValue, rightValue, err = self.evalInfix(ctx); err != nil {
 		return
 	}
-
+	v, err = lessThan(self, leftValue, rightValue)
-	if IsNumber(leftValue) && IsNumber(rightValue) {
-		if IsInteger(leftValue) && IsInteger(rightValue) {
-			li, _ := leftValue.(int64)
-			ri, _ := rightValue.(int64)
-			v = li < ri
-		} else {
-			v = numAsFloat(leftValue) < numAsFloat(rightValue)
-		}
-	} else if IsString(leftValue) && IsString(rightValue) {
-		ls, _ := leftValue.(string)
-		rs, _ := rightValue.(string)
-		v = ls < rs
-	} else {
-		err = self.errIncompatibleTypes(leftValue, rightValue)
-	}
 	return
 }
 
@@ -141,6 +141,19 @@ 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)
+			} else {
+				isLessEq, err = equals(a, b, nil)
+			}
+		}
+	}
+	return
+}
+
 func evalLessEqual(ctx ExprContext, self *term) (v any, err error) {
 	var leftValue, rightValue any
 
@@ -148,21 +161,8 @@ func evalLessEqual(ctx ExprContext, self *term) (v any, err error) {
 		return
 	}
 
-	if IsNumber(leftValue) && IsNumber(rightValue) {
+	v, err = lessThanOrEqual(self, leftValue, rightValue)
-		if IsInteger(leftValue) && IsInteger(rightValue) {
+
-			li, _ := leftValue.(int64)
-			ri, _ := rightValue.(int64)
-			v = li <= ri
-		} else {
-			v = numAsFloat(leftValue) <= numAsFloat(rightValue)
-		}
-	} else if IsString(leftValue) && IsString(rightValue) {
-		ls, _ := leftValue.(string)
-		rs, _ := rightValue.(string)
-		v = ls <= rs
-	} else {
-		err = self.errIncompatibleTypes(leftValue, rightValue)
-	}
 	return
 }
 
@@ -170,9 +170,7 @@ func evalLessEqual(ctx ExprContext, self *term) (v any, err error) {
 
 func newGreaterTerm(tk *Token) (inst *term) {
 	return &term{
-		tk: *tk,
+		tk:       *tk,
-		// class:    classOperator,
-		// kind:     kindBool,
 		children: make([]*term, 0, 2),
 		position: posInfix,
 		priority: priRelational,
@@ -181,10 +179,13 @@ func newGreaterTerm(tk *Token) (inst *term) {
 }
 
 func evalGreater(ctx ExprContext, self *term) (v any, err error) {
-	if v, err = evalLessEqual(ctx, self); err == nil {
+	var leftValue, rightValue any
-		b, _ := toBool(v)
+
-		v = !b
+	if leftValue, rightValue, err = self.evalInfix(ctx); err != nil {
+		return
 	}
+
+	v, err = lessThan(self, rightValue, leftValue)
 	return
 }
 
@@ -192,9 +193,7 @@ func evalGreater(ctx ExprContext, self *term) (v any, err error) {
 
 func newGreaterEqualTerm(tk *Token) (inst *term) {
 	return &term{
-		tk: *tk,
+		tk:       *tk,
-		// class:    classOperator,
-		// kind:     kindBool,
 		children: make([]*term, 0, 2),
 		position: posInfix,
 		priority: priRelational,
@@ -203,10 +202,13 @@ func newGreaterEqualTerm(tk *Token) (inst *term) {
 }
 
 func evalGreaterEqual(ctx ExprContext, self *term) (v any, err error) {
-	if v, err = evalLess(ctx, self); err == nil {
+	var leftValue, rightValue any
-		b, _ := toBool(v)
+
-		v = !b
+	if leftValue, rightValue, err = self.evalInfix(ctx); err != nil {
+		return
 	}
+
+	v, err = lessThanOrEqual(self, rightValue, leftValue)
 	return
 }
 

operator-sum.go

@@ -38,23 +38,6 @@ func evalPlus(ctx ExprContext, self *term) (v any, err error) {
 			rightInt, _ := rightValue.(int64)
 			v = leftInt + rightInt
 		}
-		// } else if IsList(leftValue) || IsList(rightValue) {
-		// 	var leftList, rightList *ListType
-		// 	var ok bool
-		// 	if leftList, ok = leftValue.(*ListType); !ok {
-		// 		leftList = &ListType{leftValue}
-		// 	}
-		// 	if rightList, ok = rightValue.(*ListType); !ok {
-		// 		rightList = &ListType{rightValue}
-		// 	}
-		// 	sumList := make(ListType, 0, len(*leftList)+len(*rightList))
-		// 	for _, item := range *leftList {
-		// 		sumList = append(sumList, item)
-		// 	}
-		// 	for _, item := range *rightList {
-		// 		sumList = append(sumList, item)
-		// 	}
-		// 	v = &sumList
 	} else if IsList(leftValue) && IsList(rightValue) {
 		var leftList, rightList *ListType
 		leftList, _ = leftValue.(*ListType)

parser.go

@@ -6,7 +6,6 @@ package expr
 
 import (
 	"errors"
-	"fmt"
 )
 
 //-------- parser
@@ -23,34 +22,28 @@ func NewParser(ctx ExprContext) (p *parser) {
 }
 
 func (self *parser) parseFuncCall(scanner *scanner, allowVarRef bool, tk *Token) (tree *term, err error) {
-	// name, _ := tk.Value.(string)
-	// funcObj := self.ctx.GetFuncInfo(name)
-	// if funcObj == nil {
-	// 	err = fmt.Errorf("unknown function %s()", name)
-	// 	return
-	// }
-	// maxArgs := funcObj.MaxArgs()
-	// if maxArgs < 0 {
-	// 	maxArgs = funcObj.MinArgs() + 10
-	// }
-	// args := make([]*term, 0, maxArgs)
 	args := make([]*term, 0, 10)
+	itemExpected := false
 	lastSym := SymUnknown
 	for lastSym != SymClosedRound && lastSym != SymEos {
 		var subTree *ast
-		if subTree, err = self.parseItem(scanner, allowVarRef, SymComma, SymClosedRound); err == nil {
+		if subTree, err = self.parseItem(scanner, allowVarRef, SymComma, SymClosedRound); err != nil {
-			if subTree.root != nil {
-				args = append(args, subTree.root)
-			}
-		} else {
 			break
 		}
+		prev := scanner.Previous()
+		if subTree.root != nil {
+			args = append(args, subTree.root)
+		} else if itemExpected {
+			err = prev.ErrorExpectedGot("function-param-value")
+			break
+		}
+
+		itemExpected = prev.Sym == SymComma
 		lastSym = scanner.Previous().Sym
 	}
 	if err == nil {
-		// TODO Check arguments
 		if lastSym != SymClosedRound {
-			err = errors.New("unterminate arguments list")
+			err = errors.New("unterminated arguments list")
 		} else {
 			tree = newFuncCallTerm(tk, args)
 		}
@@ -58,62 +51,12 @@ func (self *parser) parseFuncCall(scanner *scanner, allowVarRef bool, tk *Token)
 	return
 }
 
-// func (self *parser) parseFuncDef(scanner *scanner) (tree *term, err error) {
-// 	// Example: "add = func(x,y) {x+y}
-// 	var body *ast
-// 	args := make([]*term, 0)
-// 	lastSym := SymUnknown
-// 	itemExpected := false
-// 	tk := scanner.Previous()
-// 	for lastSym != SymClosedRound && lastSym != SymEos {
-// 		var subTree *ast
-// 		if subTree, err = self.parseItem(scanner, true, SymComma, SymClosedRound); err == nil {
-// 			if subTree.root != nil {
-// 				if subTree.root.symbol() == SymIdentifier {
-// 					args = append(args, subTree.root)
-// 				} else {
-// 					err = tk.ErrorExpectedGotString("param-name", subTree.root.String())
-// 				}
-// 			} else if itemExpected {
-// 				prev := scanner.Previous()
-// 				err = prev.ErrorExpectedGot("function-param")
-// 				break
-// 			}
-// 		} else {
-// 			break
-// 		}
-// 		lastSym = scanner.Previous().Sym
-// 		itemExpected = lastSym == SymComma
-// 	}
-
-// 	if err == nil && lastSym != SymClosedRound {
-// 		err = tk.ErrorExpectedGot(")")
-// 	}
-// 	if err == nil {
-// 		tk = scanner.Next()
-// 		if tk.Sym == SymOpenBrace {
-// 			body, err = self.parseGeneral(scanner, true, true, SymClosedBrace)
-// 		} else {
-// 			err = tk.ErrorExpectedGot("{")
-// 		}
-// 	}
-// 	if err == nil {
-// 		// TODO Check arguments
-// 		if scanner.Previous().Sym != SymClosedBrace {
-// 			err = scanner.Previous().ErrorExpectedGot("}")
-// 		} else {
-// 			tk = scanner.makeValueToken(SymExpression, "", body)
-// 			tree = newFuncDefTerm(tk, args)
-// 		}
-// 	}
-// 	return
-// }
-
 func (self *parser) parseFuncDef(scanner *scanner) (tree *term, err error) {
 	// Example: "add = func(x,y) {x+y}
 	var body *ast
 	args := make([]*term, 0)
 	lastSym := SymUnknown
+	defaultParamsStarted := false
 	itemExpected := false
 	tk := scanner.Previous()
 	for lastSym != SymClosedRound && lastSym != SymEos {
@@ -122,9 +65,20 @@ func (self *parser) parseFuncDef(scanner *scanner) (tree *term, err error) {
 			param := newTerm(tk)
 			args = append(args, param)
 			tk = scanner.Next()
+			if tk.Sym == SymEqual {
+				var paramExpr *ast
+				defaultParamsStarted = true
+				if paramExpr, err = self.parseItem(scanner, false, SymComma, SymClosedRound); err != nil {
+					break
+				}
+				param.forceChild(paramExpr.root)
+			} else if defaultParamsStarted {
+				err = tk.Errorf("can't mix default and non-default parameters")
+				break
+			}
 		} else if itemExpected {
 			prev := scanner.Previous()
-			err = prev.ErrorExpectedGot("function-param")
+			err = prev.ErrorExpectedGot("function-param-spec")
 			break
 		}
 		lastSym = scanner.Previous().Sym
@@ -143,7 +97,6 @@ func (self *parser) parseFuncDef(scanner *scanner) (tree *term, err error) {
 		}
 	}
 	if err == nil {
-		// TODO Check arguments
 		if scanner.Previous().Sym != SymClosedBrace {
 			err = scanner.Previous().ErrorExpectedGot("}")
 		} else {
@@ -154,15 +107,34 @@ func (self *parser) parseFuncDef(scanner *scanner) (tree *term, err error) {
 	return
 }
 
-func (self *parser) parseList(scanner *scanner, allowVarRef bool) (subtree *term, err error) {
+func (self *parser) parseList(scanner *scanner, parsingIndeces bool, allowVarRef bool) (subtree *term, err error) {
+	r, c := scanner.lastPos()
 	args := make([]*term, 0)
 	lastSym := SymUnknown
 	itemExpected := false
 	for lastSym != SymClosedSquare && lastSym != SymEos {
 		var subTree *ast
+		zeroRequired := scanner.current.Sym == SymColon
 		if subTree, err = self.parseItem(scanner, allowVarRef, SymComma, SymClosedSquare); err == nil {
-			if subTree.root != nil {
+			root := subTree.root
-				args = append(args, subTree.root)
+			if root != nil {
+				if !parsingIndeces && root.symbol() == SymColon {
+					err = root.Errorf("unexpected range expression")
+					break
+				}
+				args = append(args, root)
+				if parsingIndeces && root.symbol() == SymColon && zeroRequired { //len(root.children) == 0 {
+					if len(root.children) == 1 {
+						root.children = append(root.children, root.children[0])
+					} else if len(root.children) > 1 {
+						err = root.Errorf("invalid range specification")
+						break
+					}
+					zeroTk := NewValueToken(root.tk.row, root.tk.col, SymInteger, "0", int64(0))
+					zeroTerm := newTerm(zeroTk)
+					zeroTerm.setParent(root)
+					root.children[0] = zeroTerm
+				}
 			} else if itemExpected {
 				prev := scanner.Previous()
 				err = prev.ErrorExpectedGot("list-item")
@@ -175,11 +147,10 @@ func (self *parser) parseList(scanner *scanner, allowVarRef bool) (subtree *term
 		itemExpected = lastSym == SymComma
 	}
 	if err == nil {
-		// TODO Check arguments
 		if lastSym != SymClosedSquare {
 			err = scanner.Previous().ErrorExpectedGot("]")
 		} else {
-			subtree = newListTerm(args)
+			subtree = newListTerm(r, c, args)
 		}
 	}
 	return
@@ -207,7 +178,6 @@ func (self *parser) parseIterDef(scanner *scanner, allowVarRef bool) (subtree *t
 		itemExpected = lastSym == SymComma
 	}
 	if err == nil {
-		// TODO Check arguments
 		if lastSym != SymClosedRound {
 			err = scanner.Previous().ErrorExpectedGot(")")
 		} else {
@@ -234,7 +204,6 @@ func (self *parser) parseDictKey(scanner *scanner, allowVarRef bool) (key any, e
 			key = tk.Value
 		}
 	} else {
-		// err = tk.Errorf("expected dictionary key or closed brace, got %q", tk)
 		err = tk.ErrorExpectedGot("dictionary-key or }")
 	}
 	return
@@ -272,7 +241,6 @@ func (self *parser) parseDictionary(scanner *scanner, allowVarRef bool) (subtree
 		itemExpected = lastSym == SymComma
 	}
 	if err == nil {
-		// TODO Check arguments
 		if lastSym != SymClosedBrace {
 			err = scanner.Previous().ErrorExpectedGot("}")
 		} else {
@@ -294,14 +262,14 @@ func (self *parser) parseSelectorCase(scanner *scanner, allowVarRef bool, defaul
 			err = tk.Errorf("case list in default clause")
 			return
 		}
-		if filterList, err = self.parseList(scanner, allowVarRef); err != nil {
+		if filterList, err = self.parseList(scanner, false, allowVarRef); err != nil {
 			return
 		}
 		tk = scanner.Next()
 		startRow = tk.row
 		startCol = tk.col
 	} else if !defaultCase {
-		filterList = newListTerm(make([]*term, 0))
+		filterList = newListTerm(startRow, startCol, make([]*term, 0))
 	}
 
 	if tk.Sym == SymOpenBrace {
@@ -352,13 +320,21 @@ func (self *parser) Parse(scanner *scanner, termSymbols ...Symbol) (tree *ast, e
 	return self.parseGeneral(scanner, true, false, termSymbols...)
 }
 
+func couldBeACollection(t *term) bool {
+	var sym = SymUnknown
+	if t != nil {
+		sym = t.symbol()
+	}
+	return sym == SymList || sym == SymString || sym == SymDict || sym == SymExpression || sym == SymVariable
+}
+
 func (self *parser) parseGeneral(scanner *scanner, allowForest bool, allowVarRef bool, termSymbols ...Symbol) (tree *ast, err error) {
 	var selectorTerm *term = nil
 	var currentTerm *term = nil
 	var tk *Token
 	tree = NewAst()
 	firstToken := true
-	lastSym := SymUnknown
+	// lastSym := SymUnknown
 	for tk = scanner.Next(); err == nil && tk != nil && !tk.IsTerm(termSymbols); tk = scanner.Next() {
 		if tk.Sym == SymComment {
 			continue
@@ -368,6 +344,8 @@ func (self *parser) parseGeneral(scanner *scanner, allowForest bool, allowVarRef
 			if allowForest {
 				tree.ToForest()
 				firstToken = true
+				currentTerm = nil
+				selectorTerm = nil
 				continue
 			} else {
 				err = tk.Errorf(`unexpected token %q, expected ",", "]", or ")"`, tk.source)
@@ -401,20 +379,33 @@ func (self *parser) parseGeneral(scanner *scanner, allowForest bool, allowVarRef
 			}
 		case SymOpenSquare:
 			var listTerm *term
-			if listTerm, err = self.parseList(scanner, allowVarRef); err == nil {
+			parsingIndeces := couldBeACollection(currentTerm)
-				err = tree.addTerm(listTerm)
+			if listTerm, err = self.parseList(scanner, parsingIndeces, allowVarRef); err == nil {
+				if parsingIndeces {
+					indexTk := NewToken(listTerm.tk.row, listTerm.tk.col, SymIndex, listTerm.source())
+					indexTerm := newTerm(indexTk)
+					if err = tree.addTerm(indexTerm); err == nil {
+						err = tree.addTerm(listTerm)
+					}
+				} else {
+					err = tree.addTerm(listTerm)
+				}
 				currentTerm = listTerm
 			}
 		case SymOpenBrace:
-			var mapTerm *term
+			if currentTerm != nil && currentTerm.symbol() == SymColon {
-			if mapTerm, err = self.parseDictionary(scanner, allowVarRef); err == nil {
+				err = currentTerm.Errorf(`selector-case outside of a selector context`)
-				err = tree.addTerm(mapTerm)
+			} else {
-				currentTerm = mapTerm
+				var mapTerm *term
+				if mapTerm, err = self.parseDictionary(scanner, allowVarRef); err == nil {
+					err = tree.addTerm(mapTerm)
+					currentTerm = mapTerm
+				}
 			}
 		case SymEqual:
-			if err = checkPrevSymbol(lastSym, SymIdentifier, tk); err == nil {
+			// if err = checkPrevSymbol(lastSym, SymIdentifier, tk); err == nil {
-				currentTerm, err = tree.addToken2(tk)
+			currentTerm, err = tree.addToken2(tk)
-			}
+			// }
 		case SymFuncDef:
 			var funcDefTerm *term
 			if funcDefTerm, err = self.parseFuncDef(scanner); err == nil {
@@ -439,14 +430,16 @@ func (self *parser) parseGeneral(scanner *scanner, allowForest bool, allowVarRef
 			}
 		case SymColon, SymDoubleColon:
 			var caseTerm *term
-			if selectorTerm == nil {
+			if selectorTerm != nil {
-				err = tk.Errorf("selector-case outside of a selector context")
+				if caseTerm, err = self.parseSelectorCase(scanner, allowVarRef, tk.Sym == SymDoubleColon); err == nil {
-			} else if caseTerm, err = self.parseSelectorCase(scanner, allowVarRef, tk.Sym == SymDoubleColon); err == nil {
+					addSelectorCase(selectorTerm, caseTerm)
-				addSelectorCase(selectorTerm, caseTerm)
+					currentTerm = caseTerm
-				currentTerm = caseTerm
+					if tk.Sym == SymDoubleColon {
-				if tk.Sym == SymDoubleColon {
+						selectorTerm = nil
-					selectorTerm = nil
+					}
 				}
+			} else {
+				currentTerm, err = tree.addToken2(tk)
 			}
 		default:
 			currentTerm, err = tree.addToken2(tk)
@@ -456,7 +449,7 @@ func (self *parser) parseGeneral(scanner *scanner, allowForest bool, allowVarRef
 			selectorTerm = nil
 
 		}
-		lastSym = tk.Sym
+		// lastSym = tk.Sym
 	}
 	if err == nil {
 		err = tk.Error()
@@ -464,9 +457,9 @@ func (self *parser) parseGeneral(scanner *scanner, allowForest bool, allowVarRef
 	return
 }
 
-func checkPrevSymbol(lastSym, wantedSym Symbol, tk *Token) (err error) {
+// func checkPrevSymbol(lastSym, wantedSym Symbol, tk *Token) (err error) {
-	if lastSym != wantedSym {
+// 	if lastSym != wantedSym {
-		err = fmt.Errorf(`assign operator (%q) must be preceded by a variable`, tk.source)
+// 		err = fmt.Errorf(`assign operator (%q) must be preceded by a variable`, tk.source)
-	}
+// 	}
-	return
+// 	return
-}
+// }

scanner.go

@@ -74,6 +74,14 @@ func (self *scanner) unreadChar() (err error) {
 	return
 }
 
+func (self *scanner) lastPos() (r, c int) {
+	if self.prev != nil {
+		r = self.prev.row
+		c = self.prev.col
+	}
+	return
+}
+
 func (self *scanner) Previous() *Token {
 	return self.prev
 }

simple-func-store.go.bak

@@ -1,244 +0,0 @@
-// Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
-// All rights reserved.
-
-// simple-func-store.go
-package expr
-
-import (
-	"fmt"
-	"slices"
-	"strings"
-)
-
-type SimpleFuncStore struct {
-	SimpleVarStore
-	funcStore map[string]*funcInfo
-}
-
-type paramFlags uint16
-
-const (
-	pfOptional paramFlags = 1 << iota
-	pfRepeat
-)
-
-type funcParamInfo struct {
-	name         string
-	flags        paramFlags
-	defaultValue any
-}
-
-func newFuncParam(name string) *funcParamInfo {
-	return &funcParamInfo{name: name}
-}
-
-func newFuncParamFlag(name string, flags paramFlags) *funcParamInfo {
-	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 "any"
-}
-
-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
-}
-
-type funcInfo struct {
-	name       string
-	minArgs    int
-	maxArgs    int
-	functor    Functor
-	params     []ExprFuncParam
-	returnType string
-}
-
-func (info *funcInfo) Params() []ExprFuncParam {
-	return info.params
-}
-
-func (info *funcInfo) ReturnType() string {
-	return info.returnType
-}
-
-func (info *funcInfo) ToString(opt FmtOpt) string {
-	var sb strings.Builder
-	sb.WriteByte('(')
-	if info.params != nil {
-		for i, p := range info.params {
-			if i > 0 {
-				sb.WriteString(", ")
-			}
-			sb.WriteString(p.Name())
-			if p.IsOptional() {
-				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)
-	}
-	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 NewSimpleFuncStore() *SimpleFuncStore {
-	ctx := &SimpleFuncStore{
-		SimpleVarStore: SimpleVarStore{varStore: make(map[string]any)},
-		funcStore:      make(map[string]*funcInfo),
-	}
-	//ImportBuiltinsFuncs(ctx)
-	return ctx
-}
-
-func (ctx *SimpleFuncStore) Clone() ExprContext {
-	svs := ctx.SimpleVarStore
-	return &SimpleFuncStore{
-		// SimpleVarStore: SimpleVarStore{varStore: CloneMap(ctx.varStore)},
-		SimpleVarStore: SimpleVarStore{varStore: svs.cloneVars()},
-		funcStore:      CloneFilteredMap(ctx.funcStore, func(name string) bool { return name[0] != '@' }),
-	}
-}
-
-func funcsCtxToBuilder(sb *strings.Builder, ctx ExprContext, indent int) {
-	sb.WriteString("funcs: {\n")
-	first := true
-	names := ctx.EnumFuncs(func(name string) bool { return true })
-	slices.Sort(names)
-	for _, name := range names {
-		if first {
-			first = false
-		} else {
-			sb.WriteByte(',')
-			sb.WriteByte('\n')
-		}
-		value, _ := ctx.GetFuncInfo(name)
-		sb.WriteString(strings.Repeat("\t", indent+1))
-		sb.WriteString(name)
-		//sb.WriteString("=")
-		if formatter, ok := value.(Formatter); ok {
-			sb.WriteString(formatter.ToString(0))
-		} else {
-			sb.WriteString(fmt.Sprintf("%v", value))
-		}
-	}
-	sb.WriteString("\n}\n")
-}
-
-func (ctx *SimpleFuncStore) ToString(opt FmtOpt) string {
-	var sb strings.Builder
-	sb.WriteString(ctx.SimpleVarStore.ToString(opt))
-	funcsCtxToBuilder(&sb, ctx, 0)
-	return sb.String()
-}
-
-func (ctx *SimpleFuncStore) GetFuncInfo(name string) (info ExprFunc, exists bool) {
-	info, exists = ctx.funcStore[name]
-	return
-}
-
-// func (ctx *SimpleFuncStore) RegisterFunc(name string, functor Functor, minArgs, maxArgs int) {
-// 	ctx.funcStore[name] = &funcInfo{name: name, minArgs: minArgs, maxArgs: maxArgs, functor: functor}
-// }
-
-func (ctx *SimpleFuncStore) RegisterFuncInfo(info ExprFunc) {
-	ctx.funcStore[info.Name()], _ = info.(*funcInfo)
-}
-
-func (ctx *SimpleFuncStore) RegisterFunc2(name string, functor Functor, returnType string, params []ExprFuncParam) error {
-	var minArgs = 0
-	var maxArgs = 0
-	if params != nil {
-		for _, p := range params {
-			if maxArgs == -1 {
-				return fmt.Errorf("no more params can be specified after the ellipsis symbol: %q", p.Name())
-				// } else if p.IsRepeat() {
-				// 	maxArgs = -1
-				// 	continue
-			}
-			if p.IsOptional() {
-				maxArgs++
-			} else if maxArgs == minArgs {
-				minArgs++
-				maxArgs++
-			} else {
-				return fmt.Errorf("can't specify non-optional param after optional ones: %q", p.Name())
-			}
-			if p.IsRepeat() {
-				maxArgs = -1
-			}
-		}
-	}
-	ctx.funcStore[name] = &funcInfo{
-		name: name, minArgs: minArgs, maxArgs: maxArgs, functor: functor, returnType: returnType, params: params,
-	}
-	return nil
-}
-
-func (ctx *SimpleFuncStore) EnumFuncs(acceptor func(name string) (accept bool)) (funcNames []string) {
-	funcNames = make([]string, 0)
-	for name := range ctx.funcStore {
-		if acceptor != nil {
-			if acceptor(name) {
-				funcNames = append(funcNames, name)
-			}
-		} else {
-			funcNames = append(funcNames, name)
-		}
-	}
-	return
-}
-
-func (ctx *SimpleFuncStore) Call(name string, args []any) (result any, err error) {
-	if info, exists := ctx.funcStore[name]; exists {
-		functor := info.functor
-		result, err = functor.Invoke(ctx, name, args)
-	} else {
-		err = fmt.Errorf("unknown function %s()", name)
-	}
-	return
-}

simple-store.go

@@ -12,29 +12,40 @@ import (
 
 type SimpleStore struct {
 	varStore  map[string]any
-	funcStore map[string]*funcInfo
+	funcStore map[string]ExprFunc
 }
 
 func NewSimpleStore() *SimpleStore {
 	ctx := &SimpleStore{
 		varStore:  make(map[string]any),
-		funcStore: make(map[string]*funcInfo),
+		funcStore: make(map[string]ExprFunc),
 	}
-	//ImportBuiltinsFuncs(ctx)
 	return ctx
 }
 
+func filterRefName(name string) bool  { return name[0] != '@' }
+func filterPrivName(name string) bool { return name[0] != '_' }
+
 func (ctx *SimpleStore) Clone() ExprContext {
 	return &SimpleStore{
-		varStore:  CloneFilteredMap(ctx.varStore, func(name string) bool { return name[0] != '@' }),
+		varStore:  CloneFilteredMap(ctx.varStore, filterRefName),
-		funcStore: CloneFilteredMap(ctx.funcStore, func(name string) bool { return name[0] != '@' }),
+		funcStore: CloneFilteredMap(ctx.funcStore, filterRefName),
+	}
+}
+
+func (ctx *SimpleStore) Merge(src ExprContext) {
+	for _, name := range src.EnumVars(filterRefName) {
+		ctx.varStore[name], _ = src.GetVar(name)
+	}
+	for _, name := range src.EnumFuncs(filterRefName) {
+		ctx.funcStore[name], _ = src.GetFuncInfo(name)
 	}
 }
 
 func varsCtxToBuilder(sb *strings.Builder, ctx ExprContext, indent int) {
 	sb.WriteString("vars: {\n")
 	first := true
-	for _, name := range ctx.EnumVars(func(name string) bool { return name[0] != '_' }) {
+	for _, name := range ctx.EnumVars(filterPrivName) {
 		if first {
 			first = false
 		} else {
@@ -80,8 +91,6 @@ func funcsCtxToBuilder(sb *strings.Builder, ctx ExprContext, indent int) {
 		}
 		value, _ := ctx.GetFuncInfo(name)
 		sb.WriteString(strings.Repeat("\t", indent+1))
-		sb.WriteString(name)
-		//sb.WriteString("=")
 		if formatter, ok := value.(Formatter); ok {
 			sb.WriteString(formatter.ToString(0))
 		} else {
@@ -163,8 +172,8 @@ func (ctx *SimpleStore) EnumFuncs(acceptor func(name string) (accept bool)) (fun
 }
 
 func (ctx *SimpleStore) Call(name string, args []any) (result any, err error) {
-	if info, exists := ctx.funcStore[name]; exists {
+	if info, exists := GetLocalFuncInfo(ctx, name); exists {
-		functor := info.functor
+		functor := info.Functor()
 		result, err = functor.Invoke(ctx, name, args)
 	} else {
 		err = fmt.Errorf("unknown function %s()", name)

simple-var-store.go.bak

@@ -1,126 +0,0 @@
-// Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
-// All rights reserved.
-
-// simple-var-store.go
-package expr
-
-import (
-	"fmt"
-	"strings"
-)
-
-type SimpleVarStore struct {
-	varStore map[string]any
-}
-
-func NewSimpleVarStore() *SimpleVarStore {
-	return &SimpleVarStore{
-		varStore: make(map[string]any),
-	}
-}
-
-func (ctx *SimpleVarStore) cloneVars() (vars map[string]any) {
-	return CloneFilteredMap(ctx.varStore, func(name string) bool { return name[0] != '@' })
-}
-
-func (ctx *SimpleVarStore) Clone() (clone ExprContext) {
-	// fmt.Println("*** Cloning context ***")
-	clone = &SimpleVarStore{
-		varStore: ctx.cloneVars(),
-	}
-	return clone
-}
-
-func (ctx *SimpleVarStore) GetVar(varName string) (v any, exists bool) {
-	v, exists = ctx.varStore[varName]
-	return
-}
-
-func (ctx *SimpleVarStore) UnsafeSetVar(varName string, value any) {
-	// fmt.Printf("[%p] setVar(%v, %v)\n", ctx, varName, value)
-	ctx.varStore[varName] = value
-}
-
-func (ctx *SimpleVarStore) SetVar(varName string, value any) {
-	// fmt.Printf("[%p] SetVar(%v, %v)\n", ctx, varName, value)
-	if allowedValue, ok := fromGenericAny(value); ok {
-		ctx.varStore[varName] = allowedValue
-	} else {
-		panic(fmt.Errorf("unsupported type %T of value %v", value, value))
-	}
-}
-
-func (ctx *SimpleVarStore) EnumVars(acceptor func(name string) (accept bool)) (varNames []string) {
-	varNames = make([]string, 0)
-	for name := range ctx.varStore {
-		if acceptor != nil {
-			if acceptor(name) {
-				varNames = append(varNames, name)
-			}
-		} else {
-			varNames = append(varNames, name)
-		}
-	}
-	return
-}
-
-func (ctx *SimpleVarStore) GetFuncInfo(name string) (f ExprFunc, exists bool) {
-	return
-}
-
-func (ctx *SimpleVarStore) Call(name string, args []any) (result any, err error) {
-	return
-}
-
-// func (ctx *SimpleVarStore) RegisterFunc(name string, functor Functor, minArgs, maxArgs int) {
-// }
-func (ctx *SimpleVarStore) RegisterFuncInfo(info ExprFunc) {
-}
-func (ctx *SimpleVarStore) RegisterFunc2(name string, f Functor, returnType string, param []ExprFuncParam) error {
-	return nil
-}
-
-func (ctx *SimpleVarStore) EnumFuncs(acceptor func(name string) (accept bool)) (funcNames []string) {
-	return
-}
-
-func varsCtxToBuilder(sb *strings.Builder, ctx ExprContext, indent int) {
-	sb.WriteString("vars: {\n")
-	first := true
-	for _, name := range ctx.EnumVars(func(name string) bool { return name[0] != '_' }) {
-		if first {
-			first = false
-		} else {
-			sb.WriteByte(',')
-			sb.WriteByte('\n')
-		}
-
-		value, _ := ctx.GetVar(name)
-		sb.WriteString(strings.Repeat("\t", indent+1))
-		sb.WriteString(name)
-		sb.WriteString(": ")
-		if f, ok := value.(Formatter); ok {
-			sb.WriteString(f.ToString(0))
-		} else if _, ok = value.(Functor); ok {
-			sb.WriteString("func(){}")
-			// } else if _, ok = value.(map[any]any); ok {
-			// 	sb.WriteString("dict{}")
-		} else {
-			sb.WriteString(fmt.Sprintf("%v", value))
-		}
-	}
-	sb.WriteString(strings.Repeat("\t", indent))
-	sb.WriteString("\n}\n")
-}
-
-func varsCtxToString(ctx ExprContext, indent int) string {
-	var sb strings.Builder
-	varsCtxToBuilder(&sb, ctx, indent)
-	return sb.String()
-}
-
-func (ctx *SimpleVarStore) ToString(opt FmtOpt) string {
-	var sb strings.Builder
-	varsCtxToBuilder(&sb, ctx, 0)
-	return sb.String()
-}

symbol.go

@@ -85,6 +85,7 @@ const (
 	SymFuncDef
 	SymList
 	SymDict
+	SymIndex
 	SymExpression
 	SymSelector     // <selector> ::= <expr> "?" <selector-case> {":" <selector-case>} ["::" <default-selector-case>]
 	SymSelectorCase // <selector-case> ::= [<list>] "{" <multi-expr> "}"

t_ast_test.go

@@ -1,7 +1,7 @@
 // Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
 // All rights reserved.
 
-// ast_test.go
+// t_ast_test.go
 package expr
 
 import (

t_dict_test.go

@@ -1,7 +1,7 @@
 // Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
 // All rights reserved.
 
-// dict_test.go
+// t_dict_test.go
 package expr
 
 import (
@@ -24,10 +24,13 @@ func TestDictParser(t *testing.T) {
 		/*  1 */ {`{}`, map[any]any{}, nil},
 		/*  2 */ {`{123}`, nil, errors.New(`[1:6] expected ":", got "}"`)},
 		/*  3 */ {`{1:"one",2:"two",3:"three"}`, map[int64]any{int64(1): "one", int64(2): "two", int64(3): "three"}, nil},
-		/*  4 */ {`{1:"one",2:"two",3:"three"}.2`, "three", nil},
+		/*  4 */ {`{1:"one",2:"two",3:"three"}[3]`, "three", nil},
 		/*  5 */ {`#{1:"one",2:"two",3:"three"}`, int64(3), nil},
 		/*  6 */ {`{1:"one"} + {2:"two"}`, map[any]any{1: "one", 2: "two"}, nil},
 		/*  7 */ {`2 in {1:"one", 2:"two"}`, true, nil},
+		/*  8 */ {`D={"a":1, "b":2}; D["a"]=9; D`, map[any]any{"a": 9, "b": 2}, nil},
+		/*  9 */ {`D={"a":1, "b":2}; D["z"]=9; D`, map[any]any{"z": 9, "a": 1, "b": 2}, nil},
+		/* 10 */ {`D={"a":1, "b":2}; D[nil]=9`, nil, errors.New(`[1:21] index/key is nil`)},
 	}
 
 	succeeded := 0

t_expr_test.go

@@ -0,0 +1,37 @@
+// Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
+// All rights reserved.
+
+// t_expr_test.go
+package expr
+
+import (
+	"testing"
+)
+
+func TestExpr(t *testing.T) {
+	section := "Expr"
+
+	inputs := []inputType{
+		/*   1 */ {`0?{}`, nil, nil},
+		/*   2 */ {`fact=func(n){(n)?{1}::{n*fact(n-1)}}; fact(5)`, int64(120), nil},
+		/*   3 */ {`builtin "os.file"; f=openFile("test-file.txt"); line=readFile(f); closeFile(f); line`, "uno", nil},
+		/*   4 */ {`mynot=func(v){int(v)?{true}::{false}}; mynot(0)`, true, nil},
+		/*   5 */ {`1 ? {1} : [1+0] {3*(1+1)}`, int64(6), nil},
+		/*   6 */ {`
+		ds={
+			"init":func(end){@end=end; @current=0 but true},
+			"current":func(){current},
+			"next":func(){
+				((next=current+1) <= end) ? [true] {@current=next but current} :: {nil}
+			}
+		};
+		it=$(ds,3);
+		it++;
+		it++
+`, int64(1), nil},
+	}
+	// t.Setenv("EXPR_PATH", ".")
+
+	// parserTestSpec(t, section, inputs, 3)
+	parserTest(t, section, inputs)
+}

t_fractions_test.go

@@ -0,0 +1,66 @@
+// Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
+// All rights reserved.
+
+// t_fractions_test.go
+package expr
+
+import (
+	"errors"
+	"testing"
+)
+
+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},
+		/*   7 */ {`1|"5"`, nil, errors.New(`denominator must be integer, got string (5)`)},
+		/*   8 */ {`"1"|5`, nil, errors.New(`numerator must be integer, got string (1)`)},
+		/*   9 */ {`1|+5`, nil, errors.New(`[1:3] infix operator "|" requires two non-nil operands, got 1`)},
+		/*  10 */ {`1|(-2)`, newFraction(-1, 2), nil},
+		/*  11 */ {`builtin "math.arith"; add(1|2, 2|3)`, 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},
+		/*  14 */ {`builtin "math.arith"; mul(1|2, 1.0, 2)`, float64(1.0), nil},
+		/*  15 */ {`1|0`, nil, errors.New(`division by zero`)},
+		/*  16 */ {`fract(-0.5)`, newFraction(-1, 2), nil},
+		/*  17 */ {`fract("")`, (*FractionType)(nil), errors.New(`bad syntax`)},
+		/*  18 */ {`fract("-1")`, newFraction(-1, 1), nil},
+		/*  19 */ {`fract("+1")`, newFraction(1, 1), nil},
+		/*  20 */ {`fract("1a")`, (*FractionType)(nil), errors.New(`strconv.ParseInt: parsing "1a": invalid syntax`)},
+		/*  21 */ {`fract(1,0)`, nil, errors.New(`fract(): division by zero`)},
+	}
+	parserTest(t, section, inputs)
+}
+
+func TestFractionToStringSimple(t *testing.T) {
+	source := newFraction(1, 2)
+	want := "1|2"
+	got := source.ToString(0)
+	if got != want {
+		t.Errorf(`(1,2) -> result = %v [%T], want = %v [%T]`, got, got, want, want)
+	}
+}
+
+func TestFractionToStringMultiline(t *testing.T) {
+	source := newFraction(1, 2)
+	want := "1\n-\n2"
+	got := source.ToString(MultiLine)
+	if got != want {
+		t.Errorf(`(1,2) -> result = %v [%T], want = %v [%T]`, got, got, want, want)
+	}
+}
+
+// TODO Check this test: the output string ends with a space
+func _TestToStringMultilineTty(t *testing.T) {
+	source := newFraction(-1, 2)
+	want := "\x1b[4m-1\x1b[0m\n2"
+	got := source.ToString(MultiLine | TTY)
+	if got != want {
+		t.Errorf(`(1,2) -> result = %#v [%T], want = %#v [%T]`, got, got, want, want)
+	}
+}

t_func-base_test.go

@@ -0,0 +1,67 @@
+// Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
+// All rights reserved.
+
+// t_func-base_test.go
+package expr
+
+import (
+	"errors"
+	"testing"
+)
+
+func TestFuncBase(t *testing.T) {
+	section := "Func-Base"
+
+	inputs := []inputType{
+		/*   1 */ {`isNil(nil)`, true, nil},
+		/*   2 */ {`v=nil; isNil(v)`, true, nil},
+		/*   3 */ {`v=5; isNil(v)`, false, nil},
+		/*   4 */ {`int(true)`, int64(1), nil},
+		/*   5 */ {`int(false)`, int64(0), nil},
+		/*   6 */ {`int(3.1)`, int64(3), nil},
+		/*   7 */ {`int(3.9)`, int64(3), nil},
+		/*   8 */ {`int("432")`, int64(432), nil},
+		/*   9 */ {`int("1.5")`, nil, errors.New(`strconv.Atoi: parsing "1.5": invalid syntax`)},
+		/*  10 */ {`int("432", 4)`, nil, errors.New(`int(): too much params -- expected 1, got 2`)},
+		/*  11 */ {`int(nil)`, nil, errors.New(`int(): can't convert nil to int`)},
+		/*  12 */ {`isInt(2+1)`, true, nil},
+		/*  13 */ {`isInt(3.1)`, false, nil},
+		/*  14 */ {`isFloat(3.1)`, true, nil},
+		/*  15 */ {`isString("3.1")`, true, nil},
+		/*  16 */ {`isString("3" + 1)`, true, nil},
+		/*  17 */ {`isList(["3",  1])`, true, nil},
+		/*  18 */ {`isDict({"a":"3",  "b":1})`, true, nil},
+		/*  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},
+		/*  26 */ {`dec(2)`, float64(2), nil},
+		/*  27 */ {`dec(2.0)`, float64(2), nil},
+		/*  28 */ {`dec("2.0")`, float64(2), nil},
+		/*  29 */ {`dec(true)`, float64(1), nil},
+		/*  30 */ {`dec(true")`, nil, errors.New("[1:11] missing string termination \"")},
+		/*  31 */ {`dec()`, nil, errors.New(`dec(): too few params -- expected 1, got 0`)},
+		/*  32 */ {`dec(1,2,3)`, nil, errors.New(`dec(): too much 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},
+		/*  36 */ {`bool(2)`, true, nil},
+		/*  37 */ {`bool(1|2)`, true, nil},
+		/*  38 */ {`bool(1.0)`, true, nil},
+		/*  39 */ {`bool("1")`, true, nil},
+		/*  40 */ {`bool(false)`, false, nil},
+		/*  41 */ {`bool([1])`, nil, errors.New(`bool(): can't convert list to bool`)},
+		/*  42 */ {`dec(false)`, float64(0), nil},
+		/*  43 */ {`dec(1|2)`, float64(0.5), nil},
+		/*  44 */ {`dec([1])`, nil, errors.New(`dec(): can't convert list to float`)},
+		// /*  45 */ {`string([1])`, nil, errors.New(`string(): can't convert list to string`)},
+	}
+
+	t.Setenv("EXPR_PATH", ".")
+
+	// parserTestSpec(t, section, inputs, 2)
+	parserTest(t, section, inputs)
+}

t_func-import_test.go

@@ -0,0 +1,24 @@
+// Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
+// All rights reserved.
+
+// t_func-import_test.go
+package expr
+
+import (
+	"testing"
+)
+
+func TestFuncImport(t *testing.T) {
+	section := "Func-Import"
+	inputs := []inputType{
+		/*   1 */ {`builtin "import"; import("./test-funcs.expr"); (double(3+a) + 1) * two()`, int64(34), nil},
+		/*   2 */ {`builtin "import"; import("test-funcs.expr"); (double(3+a) + 1) * two()`, int64(34), nil},
+		/*   3 */ {`builtin "import"; importAll("./test-funcs.expr"); six()`, int64(6), nil},
+		/*   4 */ {`builtin "import"; import("./sample-export-all.expr"); six()`, int64(6), nil},
+	}
+
+	t.Setenv("EXPR_PATH", ".")
+
+	// parserTestSpec(t, section, inputs, 69)
+	parserTest(t, section, inputs)
+}

t_func-math-arith_test.go

@@ -0,0 +1,29 @@
+// Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
+// All rights reserved.
+
+// t_func-math-arith_test.go
+package expr
+
+import (
+	"errors"
+	"testing"
+)
+
+func TestFuncMathArith(t *testing.T) {
+	section := "Func-Math-Arith"
+	inputs := []inputType{
+		/*   1 */ {`builtin "math.arith"; add(1,2)`, int64(3), nil},
+		/*   2 */ {`builtin "math.arith"; add(1,2,3)`, int64(6), nil},
+		/*   3 */ {`builtin "math.arith"; mulX(1,2,3)`, nil, errors.New(`unknown function mulX()`)},
+		/*   4 */ {`builtin "math.arith"; add(1+4,3+2,5*(3-2))`, int64(15), nil},
+		/*   5 */ {`builtin "math.arith"; add(add(1+4),3+2,5*(3-2))`, int64(15), nil},
+		/*   6 */ {`builtin "math.arith"; add(add(1,4),/*3+2,*/5*(3-2))`, int64(10), nil},
+		/*   7 */ {`builtin "math.arith"; a=5; b=2; add(a, b*3)`, int64(11), nil},
+		/*   8 */ {`builtin "math.arith"; var2="abc"; add(1,2) but var2`, "abc", nil},
+	}
+
+	// t.Setenv("EXPR_PATH", ".")
+
+	// parserTestSpec(t, section, inputs, 69)
+	parserTest(t, section, inputs)
+}

t_func-os_test.go

@@ -0,0 +1,29 @@
+// Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
+// All rights reserved.
+
+// t_func-os_test.go
+package expr
+
+import (
+	"errors"
+	"testing"
+)
+
+func TestFuncOs(t *testing.T) {
+	section := "Func-OS"
+	inputs := []inputType{
+		/*   1 */ {`builtin "os.file"`, int64(1), nil},
+		/*   2 */ {`builtin "os.file"; handle=openFile("/etc/hosts"); closeFile(handle)`, true, nil},
+		/*   3 */ {`builtin "os.file"; handle=openFile("/etc/hostsX")`, nil, errors.New(`open /etc/hostsX: no such file or directory`)},
+		/*   4 */ {`builtin "os.file"; handle=createFile("/tmp/dummy"); closeFile(handle)`, true, nil},
+		/*   5 */ {`builtin "os.file"; handle=appendFile("/tmp/dummy"); writeFile(handle, "bye-bye"); closeFile(handle)`, true, nil},
+		/*   6 */ {`builtin "os.file"; handle=openFile("/tmp/dummy"); word=readFile(handle, "-"); closeFile(handle);word`, "bye", nil},
+		/*   7 */ {`builtin "os.file"; word=readFile(nil, "-")`, nil, errors.New(`readFileFunc(): invalid file handle`)},
+		/*   7 */ {`builtin "os.file"; writeFile(nil, "bye")`, nil, errors.New(`writeFileFunc(): invalid file handle`)},
+	}
+
+	// t.Setenv("EXPR_PATH", ".")
+
+	// parserTestSpec(t, section, inputs, 69)
+	parserTest(t, section, inputs)
+}

t_func-string_test.go

@@ -0,0 +1,69 @@
+// Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
+// All rights reserved.
+
+// t_func-string_test.go
+package expr
+
+import (
+	"errors"
+	"testing"
+)
+
+func TestFuncString(t *testing.T) {
+	section := "Func-String"
+
+	inputs := []inputType{
+		/*   1 */ {`builtin "string"; joinStr("-", "one", "two", "three")`, "one-two-three", nil},
+		/*   2 */ {`builtin "string"; joinStr("-", ["one", "two", "three"])`, "one-two-three", nil},
+		/*   3 */ {`builtin "string"; ls= ["one", "two", "three"]; joinStr("-", ls)`, "one-two-three", nil},
+		/*   4 */ {`builtin "string"; ls= ["one", "two", "three"]; joinStr(1, ls)`, nil, errors.New(`joinStr() the "separator" parameter must be a string, got a integer (1)`)},
+		/*   5 */ {`builtin "string"; ls= ["one", 2, "three"]; joinStr("-", ls)`, nil, errors.New(`joinStr() expected string, got integer (2)`)},
+		/*   6 */ {`builtin "string"; "<"+trimStr("  bye bye  ")+">"`, "<bye bye>", nil},
+		/*   7 */ {`builtin "string"; subStr("0123456789", 1,2)`, "12", nil},
+		/*   8 */ {`builtin "string"; subStr("0123456789", -3,2)`, "78", nil},
+		/*   9 */ {`builtin "string"; subStr("0123456789", -3)`, "789", nil},
+		/*  10 */ {`builtin "string"; subStr("0123456789")`, "0123456789", nil},
+		/*  11 */ {`builtin "string"; startsWithStr("0123456789", "xyz", "012")`, true, nil},
+		/*  12 */ {`builtin "string"; startsWithStr("0123456789", "xyz", "0125")`, false, nil},
+		/*  13 */ {`builtin "string"; startsWithStr("0123456789")`, nil, errors.New(`startsWithStr(): too few params -- expected 2 or more, got 1`)},
+		/*  14 */ {`builtin "string"; endsWithStr("0123456789", "xyz", "789")`, true, nil},
+		/*  15 */ {`builtin "string"; endsWithStr("0123456789", "xyz", "0125")`, false, nil},
+		/*  16 */ {`builtin "string"; endsWithStr("0123456789")`, nil, errors.New(`endsWithStr(): too few params -- expected 2 or more, got 1`)},
+		/*  17 */ {`builtin "string"; splitStr("one-two-three", "-")`, newListA("one", "two", "three"), nil},
+		/*  18 */ {`builtin "string"; joinStr("-", [1, "two", "three"])`, nil, errors.New(`joinStr() expected string, got integer (1)`)},
+		/*  19 */ {`builtin "string"; joinStr()`, nil, errors.New(`joinStr(): too few params -- expected 1 or more, got 0`)},
+
+		/*  69 */ /*{`builtin "string"; $$global`, `vars: {
+		}
+		funcs: {
+		    	add(any=0 ...) -> number,
+		    	dec(any) -> decimal,
+		    	endsWithStr(source, suffix) -> boolean,
+		    	fract(any, denominator=1) -> fraction,
+		    	import( ...) -> any,
+		    	importAll( ...) -> any,
+		    	int(any) -> integer,
+		    	isBool(any) -> boolean,
+		    	isDec(any) -> boolean,
+		    	isDict(any) -> boolean,
+		    	isFloat(any) -> boolean,
+		    	isFract(any) -> boolean,
+		    	isInt(any) -> boolean,
+		    	isList(any) -> boolean,
+		    	isNil(any) -> boolean,
+		    	isString(any) -> boolean,
+		    	joinStr(separator, item="" ...) -> string,
+		    	mul(any=1 ...) -> number,
+		    	splitStr(source, separator="", count=-1) -> list of string,
+		    	startsWithStr(source, prefix) -> boolean,
+		    	subStr(source, start=0, count=-1) -> string,
+		    	trimStr(source) -> string
+		}
+		`, nil},*/
+	}
+
+	//t.Setenv("EXPR_PATH", ".")
+
+	// parserTestSpec(t, section, inputs, 19)
+	parserTest(t, section, inputs)
+}

t_funcs_test.go

@@ -0,0 +1,61 @@
+// Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
+// All rights reserved.
+
+// t_funcs_test.go
+package expr
+
+import (
+	"errors"
+	"testing"
+)
+
+func TestFuncs(t *testing.T) {
+	section := "Funcs"
+	inputs := []inputType{
+		/*   1 */ {`two=func(){2}; two()`, int64(2), nil},
+		/*   2 */ {`double=func(x) {2*x}; (double(3))`, int64(6), nil},
+		/*   3 */ {`double=func(x){2*x}; double(3)`, int64(6), nil},
+		/*   4 */ {`double=func(x){2*x}; a=5; double(3+a) + 1`, int64(17), nil},
+		/*   5 */ {`double=func(x){2*x}; a=5; two=func() {2}; (double(3+a) + 1) * two()`, int64(34), nil},
+		/*   6 */ {`@x="hello"; @x`, nil, errors.New(`[1:3] variable references are not allowed in top level expressions: "@x"`)},
+		/*   7 */ {`f=func(){@x="hello"}; f(); x`, "hello", nil},
+		/*   8 */ {`f=func(@y){@y=@y+1}; f(2); y`, int64(3), nil},
+		/*   9 */ {`f=func(@y){g=func(){@x=5}; @y=@y+g()}; f(2); y+x`, nil, errors.New(`undefined variable or function "x"`)},
+		/*  10 */ {`f=func(@y){g=func(){@x=5}; @z=g(); @y=@y+@z}; f(2); y+z`, int64(12), nil},
+		/*  11 */ {`f=func(@y){g=func(){@x=5}; g(); @z=x; @y=@y+@z}; f(2); y+z`, int64(12), nil},
+		/*  12 */ {`f=func(@y){g=func(){@x=5}; g(); @z=x; @x=@y+@z}; f(2); y+x`, int64(9), nil},
+		/*  13 */ {`two=func(){2}; four=func(f){f()+f()}; four(two)`, int64(4), nil},
+		/*  14 */ {`two=func(){2}; two(123)`, nil, errors.New(`two(): too much params -- expected 0, got 1`)},
+		/*  15 */ {`f=func(x,n=2){x+n}; f(3)`, int64(5), nil},
+		/*  16 */ {`f=func(x,n=2,y){x+n}`, nil, errors.New(`[1:16] can't mix default and non-default parameters`)},
+		/*  17 */ {`f=func(x,n){1}; f(3,4,)`, nil, errors.New(`[1:24] expected "function-param-value", got ")"`)},
+		// /*  18 */ {`f=func(a){a*2}`, nil, errors.New(`[1:24] expected "function-param-value", got ")"`)},
+	}
+
+	// t.Setenv("EXPR_PATH", ".")
+
+	// parserTestSpec(t, section, inputs, 17)
+	parserTest(t, section, inputs)
+}
+
+func dummy(ctx ExprContext, name string, args []any) (result any, err error) {
+	return
+}
+
+func TestFunctionToStringSimple(t *testing.T) {
+	source := newGolangFunctor(dummy)
+	want := "func() {<body>}"
+	got := source.ToString(0)
+	if got != want {
+		t.Errorf(`(func() -> result = %v [%T], want = %v [%T]`, got, got, want, want)
+	}
+}
+
+func TestFunctionGetFunc(t *testing.T) {
+	source := newGolangFunctor(dummy)
+	want := ExprFunc(nil)
+	got := source.GetFunc()
+	if got != want {
+		t.Errorf(`(func() -> result = %v [%T], want = %v [%T]`, got, got, want, want)
+	}
+}

t_graph_test.go

@@ -1,10 +1,7 @@
 // Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
 // All rights reserved.
 
-// Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
+// t_graph_test.go
-// All rights reserved.
-
-// graph_test.go
 package expr
 
 import (

t_helpers_test.go

@@ -1,7 +1,7 @@
 // Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
 // All rights reserved.
 
-// helpers_test.go
+// t_helpers_test.go
 package expr
 
 import (

t_index_test.go

@@ -0,0 +1,27 @@
+// Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
+// All rights reserved.
+
+// t_index_test.go
+package expr
+
+import (
+	"errors"
+	"testing"
+)
+
+func TestCollections(t *testing.T) {
+	section := "Collection"
+	inputs := []inputType{
+		/*   1 */ {`"abcdef"[1:3]`, "bc", nil},
+		/*   2 */ {`"abcdef"[:3]`, "abc", nil},
+		/*   3 */ {`"abcdef"[1:]`, "bcdef", nil},
+		/*   4 */ {`"abcdef"[:]`, "abcdef", nil},
+		// /*   5 */ {`[0,1,2,3,4][:]`, ListType{int64(0), int64(1), int64(2), int64(3), int64(4)}, nil},
+		/*   5 */ {`"abcdef"[1:2:3]`, nil, errors.New(`[1:14] left operand '(1, 2)' [pair] and right operand '3' [integer] are not compatible with operator ":"`)},
+	}
+
+	t.Setenv("EXPR_PATH", ".")
+
+	// parserTestSpec(t, section, inputs, 5)
+	parserTest(t, section, inputs)
+}

t_iterator_test.go

@@ -1,7 +1,7 @@
 // Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
 // All rights reserved.
 
-// iterator_test.go
+// t_iterator_test.go
 package expr
 
 import "testing"

t_list_test.go

@@ -1,7 +1,7 @@
 // Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
 // All rights reserved.
 
-// list_test.go
+// t_list_test.go
 package expr
 
 import (
@@ -13,41 +13,58 @@ import (
 func TestListParser(t *testing.T) {
 	section := "List"
 
-	type inputType struct {
+	/*	type inputType struct {
-		source     string
+			source     string
-		wantResult any
+			wantResult any
-		wantErr    error
+			wantErr    error
-	}
+		}
-
+	*/
 	inputs := []inputType{
-		/*   1 */ {`[]`, []any{}, nil},
+		/*   1 */ {`[]`, newListA(), nil},
-		/*   2 */ {`[1,2,3]`, []any{int64(1), int64(2), int64(3)}, nil},
+		/*   2 */ {`[1,2,3]`, newListA(int64(1), int64(2), int64(3)), nil},
-		/*   3 */ {`[1,2,"hello"]`, []any{int64(1), int64(2), "hello"}, nil},
+		/*   3 */ {`[1,2,"hello"]`, newListA(int64(1), int64(2), "hello"), nil},
-		/*   4 */ {`[1+2, not true, "hello"]`, []any{int64(3), false, "hello"}, nil},
+		/*   4 */ {`[1+2, not true, "hello"]`, newListA(int64(3), false, "hello"), nil},
-		/*   5 */ {`[1,2]+[3]`, []any{int64(1), int64(2), int64(3)}, nil},
+		/*   5 */ {`[1,2]+[3]`, newListA(int64(1), int64(2), int64(3)), nil},
-		/*   6 */ {`[1,4,3,2]-[3]`, []any{int64(1), int64(4), int64(2)}, nil},
+		/*   6 */ {`[1,4,3,2]-[3]`, newListA(int64(1), int64(4), int64(2)), nil},
 		/*   7 */ {`add([1,4,3,2])`, int64(10), nil},
 		/*   8 */ {`add([1,[2,2],3,2])`, int64(10), nil},
 		/*   9 */ {`mul([1,4,3.0,2])`, float64(24.0), nil},
 		/*  10 */ {`add([1,"hello"])`, nil, errors.New(`add(): param nr 2 (2 in 1) has wrong type string, number expected`)},
 		/*  11 */ {`[a=1,b=2,c=3] but a+b+c`, int64(6), nil},
-		/*  12 */ {`[1,2,3] << 2+2`, []any{int64(1), int64(2), int64(3), int64(4)}, nil},
+		/*  12 */ {`[1,2,3] << 2+2`, newListA(int64(1), int64(2), int64(3), int64(4)), nil},
-		/*  13 */ {`2-1 >> [2,3]`, []any{int64(1), int64(2), int64(3)}, nil},
+		/*  13 */ {`2-1 >> [2,3]`, newListA(int64(1), int64(2), int64(3)), nil},
-		/*  14 */ {`[1,2,3].1`, int64(2), nil},
+		/*  14 */ {`[1,2,3][1]`, int64(2), nil},
-		/*  15 */ {`ls=[1,2,3] but ls.1`, int64(2), nil},
+		/*  15 */ {`ls=[1,2,3] but ls[1]`, int64(2), nil},
-		/*  16 */ {`ls=[1,2,3] but ls.(-1)`, int64(3), nil},
+		/*  16 */ {`ls=[1,2,3] but ls[-1]`, int64(3), nil},
-		/*  17 */ {`list=["one","two","three"]; list.10`, nil, errors.New(`[1:36] index 10 out of bounds`)},
+		/*  17 */ {`list=["one","two","three"]; list[10]`, nil, errors.New(`[1:34] index 10 out of bounds`)},
 		/*  18 */ {`["a", "b", "c"]`, newListA("a", "b", "c"), nil},
 		/*  19 */ {`["a", "b", "c"]`, newList([]any{"a", "b", "c"}), nil},
 		/*  20 */ {`#["a", "b", "c"]`, int64(3), nil},
 		/*  21 */ {`"b" in ["a", "b", "c"]`, true, nil},
-		/*  22 */ {`a=[1,2]; (a)<<3`, []any{1, 2, 3}, nil},
+		/*  22 */ {`a=[1,2]; (a)<<3`, newListA(int64(1), int64(2), int64(3)), nil},
-		/*  23 */ {`a=[1,2]; (a)<<3; 1`, []any{1, 2}, nil},
+		/*  23 */ {`a=[1,2]; (a)<<3; a`, newListA(int64(1), int64(2)), nil},
-
+		/*  24 */ {`["a","b","c","d"][1]`, "b", nil},
+		/*  25 */ {`["a","b","c","d"][1,1]`, nil, errors.New(`[1:19] one index only is allowed`)},
+		/*  26 */ {`[0,1,2,3,4][:]`, newListA(int64(0), int64(1), int64(2), int64(3), int64(4)), nil},
+		/*  27 */ {`["a", "b", "c"] << ;`, nil, errors.New(`[1:18] infix operator "<<" requires two non-nil operands, got 1`)},
+		/*  28 */ {`2 << 3;`, nil, errors.New(`[1:4] left operand '2' [integer] and right operand '3' [integer] are not compatible with operator "<<"`)},
+		/*  29 */ {`but >> ["a", "b", "c"]`, nil, errors.New(`[1:6] infix operator ">>" requires two non-nil operands, got 0`)},
+		/*  30 */ {`2 >> 3;`, nil, errors.New(`[1:4] left operand '2' [integer] and right operand '3' [integer] are not compatible with operator ">>"`)},
+		/*  31 */ {`a=[1,2]; a<<3`, newListA(int64(1), int64(2), int64(3)), nil},
+		/*  33 */ {`a=[1,2]; 5>>a`, newListA(int64(5), int64(1), int64(2)), nil},
+		/*  34 */ {`L=[1,2]; L[0]=9; L`, newListA(int64(9), int64(2)), nil},
+		/*  35 */ {`L=[1,2]; L[5]=9; L`, nil, errors.New(`index 5 out of bounds (0, 1)`)},
+		/*  36 */ {`L=[1,2]; L[]=9; L`, nil, errors.New(`[1:12] index/key specification expected, got [] [list]`)},
+		/*  37 */ {`L=[1,2]; L[nil]=9;`, nil, errors.New(`[1:12] index/key is nil`)},
 		// /*  8 */ {`[int(x)|x=csv("test.csv",1,all(),1)]`, []any{int64(10), int64(40), int64(20)}, nil},
 		// /*  9 */ {`sum(@[int(x)|x=csv("test.csv",1,all(),1)])`, []any{int64(10), int64(40), int64(20)}, nil},
 	}
 
+	// t.Setenv("EXPR_PATH", ".")
+
+	// parserTestSpec(t, section, inputs, 17)
+	parserTest(t, section, inputs)
+	return
 	succeeded := 0
 	failed := 0
 
@@ -61,8 +78,6 @@ func TestListParser(t *testing.T) {
 		var gotErr error
 
 		ctx := NewSimpleStore()
-		// ctx.SetVar("var1", int64(123))
-		// ctx.SetVar("var2", "abc")
 		ImportMathFuncs(ctx)
 		parser := NewParser(ctx)
 

t_module-register_test.go

@@ -0,0 +1,31 @@
+// Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
+// All rights reserved.
+
+// t_module-register_test.go
+package expr
+
+import (
+	"testing"
+)
+
+func TestIterateModules(t *testing.T) {
+	section := "Module-Register"
+
+	mods := make([]string, 0, 100)
+	IterateModules(func(name, description string, imported bool) bool {
+		mods = append(mods, name)
+		return true
+	})
+
+	t.Logf("%s -- IterateModules(): %v", section, mods)
+	if len(mods) == 0 {
+		t.Errorf("Module-List: got-length zero, expected-length greater than zero")
+	}
+
+	// IterateModules(func(name, description string, imported bool) bool {
+	// 	return false
+	// })
+	// if len(mods) > 0 {
+	// 	t.Errorf("Module-List: got-length greater than zero, expected-length zero")
+	// }
+}

t_parser_test.go

@@ -1,7 +1,7 @@
 // Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
 // All rights reserved.
 
-// parser_test.go
+// t_parser_test.go
 package expr
 
 import (
@@ -18,6 +18,8 @@ type inputType struct {
 }
 
 func TestGeneralParser(t *testing.T) {
+	section := "Parser"
+
 	inputs := []inputType{
 		/*   1 */ {`1+/*5*/2`, int64(3), nil},
 		/*   2 */ {`3 == 4`, false, nil},
@@ -115,8 +117,8 @@ func TestGeneralParser(t *testing.T) {
 		/*  94 */ {`false or true`, true, nil},
 		/*  95 */ {`false or (x==2)`, nil, errors.New(`undefined variable or function "x"`)},
 		/*  96 */ {`a=5; a`, int64(5), nil},
-		/*  97 */ {`2=5`, nil, errors.New(`assign operator ("=") must be preceded by a variable`)},
+		/*  97 */ {`2=5`, nil, errors.New(`[1:2] left operand of "=" must be a variable or a collection's item`)},
-		/*  98 */ {`2+a=5`, nil, errors.New(`[1:3] left operand of "=" must be a variable`)},
+		/*  98 */ {`2+a=5`, nil, errors.New(`[1:3] left operand of "=" must be a variable or a collection's item`)},
 		/*  99 */ {`2+(a=5)`, int64(7), nil},
 		/* 100 */ {`x ?? "default"`, "default", nil},
 		/* 101 */ {`x="hello"; x ?? "default"`, "hello", nil},
@@ -138,33 +140,15 @@ func TestGeneralParser(t *testing.T) {
 		/* 117 */ {`{"key"}`, nil, errors.New(`[1:8] expected ":", got "}"`)},
 		/* 118 */ {`{"key":}`, nil, errors.New(`[1:9] expected "dictionary-value", got "}"`)},
 		/* 119 */ {`{}`, &DictType{}, nil},
-		/* 120 */ {`1|2`, newFraction(1, 2), nil},
+		/* 120 */ {`v=10; v++; v`, int64(11), nil},
-		/* 121 */ {`1|2 + 1`, newFraction(3, 2), nil},
+		/* 121 */ {`1+1|2+0.5`, float64(2), nil},
-		/* 122 */ {`1|2 - 1`, newFraction(-1, 2), nil},
+		/* 122 */ {`1.2()`, newFraction(6, 5), nil},
-		/* 123 */ {`1|2 * 1`, newFraction(1, 2), nil},
+		/* 123 */ {`1|(2-2)`, nil, errors.New(`division by zero`)},
-		/* 124 */ {`1|2 * 2|3`, newFraction(2, 6), nil},
-		/* 125 */ {`1|2 / 2|3`, newFraction(3, 4), nil},
-		/* 126 */ {`builtin "math.arith"; add(1,2,3)`, int64(6), nil},
-		/* 127 */ {`builtin "math.arith"; mulX(1,2,3)`, nil, errors.New(`unknown function mulX()`)},
-		/* 128 */ {`builtin "math.arith"; add(1+4,3+2,5*(3-2))`, int64(15), nil},
-		/* 129 */ {`builtin "math.arith"; add(add(1+4),3+2,5*(3-2))`, int64(15), nil},
-		/* 130 */ {`builtin "math.arith"; add(add(1,4),/*3+2,*/5*(3-2))`, int64(10), nil},
-		/* 131 */ {`builtin "math.arith"; a=5; b=2; add(a, b*3)`, int64(11), nil},
-		/* 132 */ {`builtin "math.arith"; var2="abc"; add(1,2) but var2`, "abc", nil},
-		/* 133 */ {`builtin "math.arith"; add(1|2, 2|3)`, newFraction(7, 6), nil},
-		/* 134 */ {`builtin "math.arith"; add(1|2, 1.0, 2)`, float64(3.5), nil},
-		/* 135 */ {`builtin "math.arith"; mul(1|2, 2|3)`, newFraction(2, 6), nil},
-		/* 136 */ {`builtin "math.arith"; mul(1|2, 1.0, 2)`, float64(1.0), nil},
-		/* 137 */ {`builtin "os.file"`, int64(1), nil},
-		/* 138 */ {`v=10; v++; v`, int64(11), nil},
-		/* 139 */ {`1+1|2+0.5`, float64(2), nil},
-		/* 140 */ {`1.2()`, newFraction(6, 5), nil},
-		/* 141 */ {`1|(2-2)`, nil, errors.New(`division by zero`)},
 	}
 
 	// t.Setenv("EXPR_PATH", ".")
-	// parserTestSpec(t, "General", inputs, 102)
+	// parserTestSpec(t, section, inputs, 102)
-	parserTest(t, "General", inputs)
+	parserTest(t, section, inputs)
 }
 
 func parserTestSpec(t *testing.T, section string, inputs []inputType, spec ...int) {
@@ -219,7 +203,7 @@ func doTest(t *testing.T, section string, input *inputType, count int) (good boo
 	eq := reflect.DeepEqual(gotResult, input.wantResult)
 
 	if !eq /*gotResult != input.wantResult*/ {
-		t.Errorf("%d: %q -> result = %v [%T], want = %v [%T]", count, input.source, gotResult, gotResult, input.wantResult, input.wantResult)
+		t.Errorf("%d: %q -> result = %v [%s], want = %v [%s]", count, input.source, gotResult, typeName(gotResult), input.wantResult, typeName(input.wantResult))
 		good = false
 	}
 

t_relational_test.go

@@ -0,0 +1,52 @@
+// Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
+// All rights reserved.
+
+// t_template_test.go
+package expr
+
+import (
+	"testing"
+)
+
+func TestRelational(t *testing.T) {
+	section := "Relational"
+	inputs := []inputType{
+		/*   1 */ {`1 == 3-2`, true, nil},
+		/*   2 */ {`"a" == "a"`, true, nil},
+		/*   3 */ {`true == false`, false, nil},
+		/*   4 */ {`1.0 == 3.0-2`, true, nil},
+		/*   5 */ {`[1,2] == [2,1]`, false, nil},
+		/*   6 */ {`1 != 3-2`, false, nil},
+		/*   7 */ {`"a" != "a"`, false, nil},
+		/*   8 */ {`true != false`, true, nil},
+		/*   9 */ {`1.0 != 3.0-2`, false, nil},
+		/*  10 */ {`[1,2] != [2,1]`, true, nil},
+		/*  11 */ {`1|2 == 1|3`, false, nil},
+		/*  12 */ {`1|2 != 1|3`, true, nil},
+		/*  13 */ {`1|2 == 4|8`, true, nil},
+		/*  14 */ {`1 < 8`, true, nil},
+		/*  15 */ {`1 <= 8`, true, nil},
+		/*  16 */ {`"a" < "b"`, true, nil},
+		/*  17 */ {`"a" <= "b"`, true, nil},
+		/*  18 */ {`1.0 < 8`, true, nil},
+		/*  19 */ {`1.0 <= 8`, true, nil},
+		/*  20 */ {`1.0 <= 1.0`, true, nil},
+		/*  21 */ {`1.0 == 1`, true, nil},
+		/*  22 */ {`1|2 < 1|3`, false, nil},
+		/*  23 */ {`1|2 <= 1|3`, false, nil},
+		/*  24 */ {`1|2 > 1|3`, true, nil},
+		/*  25 */ {`1|2 >= 1|3`, true, nil},
+		/*  26 */ {`[1,2,3] > [2]`, true, nil},
+		/*  27 */ {`[1,2,3] > [9]`, false, nil},
+		/*  28 */ {`[1,2,3] >= [6]`, false, nil},
+		/*  29 */ {`[1,2,3] >= [2,6]`, false, nil},
+		/*  30 */ {`[1,[2,3],4] > [[3,2]]`, true, nil},
+		/*  31 */ {`[1,[2,[3,4]],5] > [[[4,3],2]]`, true, nil},
+		/*  32 */ {`[[4,3],2] IN [1,[2,[3,4]],5]`, true, nil},
+	}
+
+	// t.Setenv("EXPR_PATH", ".")
+
+	// parserTestSpec(t, section, inputs, 31)
+	parserTest(t, section, inputs)
+}

t_scanner_test.go

@@ -1,7 +1,7 @@
 // Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
 // All rights reserved.
 
-// scanner_test.go
+// t_scanner_test.go
 package expr
 
 import (

t_strings_test.go

@@ -1,7 +1,7 @@
 // Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
 // All rights reserved.
 
-// strings_test.go
+// t_strings_test.go
 package expr
 
 import (
@@ -14,8 +14,8 @@ func TestStringsParser(t *testing.T) {
 		/*  2 */ {`"uno" + 2`, `uno2`, nil},
 		/*  3 */ {`"uno" + (2+1)`, `uno3`, nil},
 		/*  4 */ {`"uno" * (2+1)`, `unounouno`, nil},
-		/*  5 */ {`"abc".1`, `b`, nil},
+		/*  5 */ {`"abc"[1]`, `b`, nil},
-		/*  5 */ {`#"abc"`, int64(3), nil},
+		/*  6 */ {`#"abc"`, int64(3), nil},
 	}
 	parserTest(t, "String", inputs)
 }

t_template_test.go

@@ -0,0 +1,21 @@
+// Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
+// All rights reserved.
+
+// t_template_test.go
+package expr
+
+import (
+	"testing"
+)
+
+func TestSomething(t *testing.T) {
+	section := "Something"
+	inputs := []inputType{
+		/*   1 */ {`1`, int64(1), nil},
+	}
+
+	// t.Setenv("EXPR_PATH", ".")
+
+	// parserTestSpec(t, section, inputs, 1)
+	parserTest(t, section, inputs)
+}

t_term_test.go

@@ -1,7 +1,7 @@
 // Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
 // All rights reserved.
 
-// term_test.go
+// t_term_test.go
 package expr
 
 import (

t_token_test.go

@@ -1,7 +1,7 @@
 // Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
 // All rights reserved.
 
-// token_test.go
+// t_token_test.go
 package expr
 
 import (

t_utils_test.go

@@ -1,7 +1,7 @@
 // Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
 // All rights reserved.
 
-// utils_test.go
+// t_utils_test.go
 package expr
 
 import (
@@ -54,6 +54,14 @@ func TestIsString(t *testing.T) {
 		succeeded++
 	}
 
+	count++
+	if isIterator("fake") {
+		t.Errorf(`%d: isIterator("fake") -> result = true, want false`, count)
+		failed++
+	} else {
+		succeeded++
+	}
+
 	count++
 	b, ok := toBool(true)
 	if !(ok && b) {
@@ -72,6 +80,15 @@ func TestIsString(t *testing.T) {
 		succeeded++
 	}
 
+	count++
+	b, ok = toBool([]int{})
+	if ok {
+		t.Errorf("%d: toBool([]) b=%v, ok=%v -> result = true, want false", count, b, ok)
+		failed++
+	} else {
+		succeeded++
+	}
+
 	t.Logf("test count: %d, succeeded count: %d, failed count: %d", count, succeeded, failed)
 }
 

term.go

@@ -12,6 +12,7 @@ type termPriority uint32
 
 const (
 	priNone termPriority = iota
+	priRange
 	priBut
 	priAssign
 	priOr
@@ -155,15 +156,15 @@ func (self *term) toInt(computedValue any, valueDescription string) (i int, err
 	if index64, ok := computedValue.(int64); ok {
 		i = int(index64)
 	} else {
-		err = self.Errorf("%s, got %T (%v)", valueDescription, computedValue, computedValue)
+		err = self.Errorf("%s, got %s (%v)", valueDescription, typeName(computedValue), computedValue)
 	}
 	return
 }
 
 func (self *term) errIncompatibleTypes(leftValue, rightValue any) error {
-	leftType := getTypeName(leftValue)
+	leftType := typeName(leftValue)
 	leftText := getFormatted(leftValue, Truncate)
-	rightType := getTypeName(rightValue)
+	rightType := typeName(rightValue)
 	rightText := getFormatted(rightValue, Truncate)
 	return self.tk.Errorf(
 		"left operand '%s' [%s] and right operand '%s' [%s] are not compatible with operator %q",
@@ -174,8 +175,8 @@ func (self *term) errIncompatibleTypes(leftValue, rightValue any) error {
 
 func (self *term) errIncompatibleType(value any) error {
 	return self.tk.Errorf(
-		"prefix/postfix operator %q do not support operand '%v' [%T]",
+		"prefix/postfix operator %q do not support operand '%v' [%s]",
-		self.source(), value, value)
+		self.source(), value, typeName(value))
 }
 
 func (self *term) Errorf(template string, args ...any) (err error) {
@@ -228,3 +229,12 @@ func (self *term) evalPrefix(ctx ExprContext) (childValue any, err error) {
 	}
 	return
 }
+
+// NOTE Temporary solution to support function parameters with default value
+
+func (self *term) forceChild(c *term) {
+	if self.children == nil {
+		self.children = make([]*term, 0, 1)
+	}
+	self.children = append(self.children, c)
+}

utils.go

@@ -40,12 +40,12 @@ func IsDict(v any) (ok bool) {
 }
 
 func IsFract(v any) (ok bool) {
-	_, ok = v.(*fraction)
+	_, ok = v.(*FractionType)
 	return ok
 }
 
 func IsRational(v any) (ok bool) {
-	if _, ok = v.(*fraction); !ok {
+	if _, ok = v.(*FractionType); !ok {
 		_, ok = v.(int64)
 	}
 	return ok
@@ -76,7 +76,7 @@ func isIterator(v any) (ok bool) {
 func numAsFloat(v any) (f float64) {
 	var ok bool
 	if f, ok = v.(float64); !ok {
-		if fract, ok := v.(*fraction); ok {
+		if fract, ok := v.(*FractionType); ok {
 			f = fract.toFloat()
 		} else {
 			i, _ := v.(int64)
@@ -204,8 +204,10 @@ func CloneFilteredMap[K comparable, V any](source map[K]V, filter func(key K) (a
 func toInt(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 %T (%v)", description, value, value)
+		err = fmt.Errorf("%s expected integer, got %s (%v)", description, typeName(value), value)
 	}
 	return
 }