diff --git a/bind-go-functions.go b/bind-go-functions.go
index 0264d80..46cf8d0 100644
--- a/bind-go-functions.go
+++ b/bind-go-functions.go
@@ -10,7 +10,7 @@ type golangFunctor struct {
 	f FuncTemplate
 }
 
-func NewGolangFunctor2(f FuncTemplate) *golangFunctor {
+func NewGolangFunctor(f FuncTemplate) *golangFunctor {
 	return &golangFunctor{f: f}
 }
 
diff --git a/builtin-base.go b/builtin-base.go
index aa73807..05b5b39 100644
--- a/builtin-base.go
+++ b/builtin-base.go
@@ -193,21 +193,21 @@ func ImportBuiltinsFuncs(ctx ExprContext) {
 		NewFuncParam(ParamValue),
 	}
 
-	ctx.RegisterFunc("isNil", NewGolangFunctor2(isNilFunc), TypeBoolean, anyParams)
-	ctx.RegisterFunc("isInt", NewGolangFunctor2(isIntFunc), TypeBoolean, anyParams)
-	ctx.RegisterFunc("isFloat", NewGolangFunctor2(isFloatFunc), TypeBoolean, anyParams)
-	ctx.RegisterFunc("isBool", NewGolangFunctor2(isBoolFunc), TypeBoolean, anyParams)
-	ctx.RegisterFunc("isString", NewGolangFunctor2(isStringFunc), TypeBoolean, anyParams)
-	ctx.RegisterFunc("isFract", NewGolangFunctor2(isFractionFunc), TypeBoolean, anyParams)
-	ctx.RegisterFunc("isRational", NewGolangFunctor2(isRationalFunc), TypeBoolean, anyParams)
-	ctx.RegisterFunc("isList", NewGolangFunctor2(isListFunc), TypeBoolean, anyParams)
-	ctx.RegisterFunc("isDict", NewGolangFunctor2(isDictionaryFunc), TypeBoolean, anyParams)
+	ctx.RegisterFunc("isNil", NewGolangFunctor(isNilFunc), TypeBoolean, anyParams)
+	ctx.RegisterFunc("isInt", NewGolangFunctor(isIntFunc), TypeBoolean, anyParams)
+	ctx.RegisterFunc("isFloat", NewGolangFunctor(isFloatFunc), TypeBoolean, anyParams)
+	ctx.RegisterFunc("isBool", NewGolangFunctor(isBoolFunc), TypeBoolean, anyParams)
+	ctx.RegisterFunc("isString", NewGolangFunctor(isStringFunc), TypeBoolean, anyParams)
+	ctx.RegisterFunc("isFract", NewGolangFunctor(isFractionFunc), TypeBoolean, anyParams)
+	ctx.RegisterFunc("isRational", NewGolangFunctor(isRationalFunc), TypeBoolean, anyParams)
+	ctx.RegisterFunc("isList", NewGolangFunctor(isListFunc), TypeBoolean, anyParams)
+	ctx.RegisterFunc("isDict", NewGolangFunctor(isDictionaryFunc), TypeBoolean, anyParams)
 
-	ctx.RegisterFunc("bool", NewGolangFunctor2(boolFunc), TypeBoolean, anyParams)
-	ctx.RegisterFunc("int", NewGolangFunctor2(intFunc), TypeInt, anyParams)
-	ctx.RegisterFunc("dec", NewGolangFunctor2(decFunc), TypeFloat, anyParams)
-	ctx.RegisterFunc("string", NewGolangFunctor2(stringFunc), TypeString, anyParams)
-	ctx.RegisterFunc("fract", NewGolangFunctor2(fractFunc), TypeFraction, []ExprFuncParam{
+	ctx.RegisterFunc("bool", NewGolangFunctor(boolFunc), TypeBoolean, anyParams)
+	ctx.RegisterFunc("int", NewGolangFunctor(intFunc), TypeInt, anyParams)
+	ctx.RegisterFunc("dec", NewGolangFunctor(decFunc), TypeFloat, anyParams)
+	ctx.RegisterFunc("string", NewGolangFunctor(stringFunc), TypeString, anyParams)
+	ctx.RegisterFunc("fract", NewGolangFunctor(fractFunc), TypeFraction, []ExprFuncParam{
 		NewFuncParam(ParamValue),
 		NewFuncParamFlagDef(ParamDenominator, PfDefault, int64(1)),
 	})
diff --git a/builtin-fmt.go b/builtin-fmt.go
index a068e9b..c721d33 100644
--- a/builtin-fmt.go
+++ b/builtin-fmt.go
@@ -44,10 +44,10 @@ func printLnFunc(ctx ExprContext, name string, args map[string]any) (result any,
 }
 
 func ImportFmtFuncs(ctx ExprContext) {
-	ctx.RegisterFunc("print", NewGolangFunctor2(printFunc), TypeInt, []ExprFuncParam{
+	ctx.RegisterFunc("print", NewGolangFunctor(printFunc), TypeInt, []ExprFuncParam{
 		NewFuncParamFlag(ParamItem, PfRepeat),
 	})
-	ctx.RegisterFunc("println", NewGolangFunctor2(printLnFunc), TypeInt, []ExprFuncParam{
+	ctx.RegisterFunc("println", NewGolangFunctor(printLnFunc), TypeInt, []ExprFuncParam{
 		NewFuncParamFlag(ParamItem, PfRepeat),
 	})
 }
diff --git a/builtin-import.go b/builtin-import.go
index 12428ed..ee002c0 100644
--- a/builtin-import.go
+++ b/builtin-import.go
@@ -65,10 +65,10 @@ func doImport(ctx ExprContext, name string, dirList []string, it Iterator) (resu
 }
 
 func ImportImportFuncs(ctx ExprContext) {
-	ctx.RegisterFunc("import", NewGolangFunctor2(importFunc), TypeAny, []ExprFuncParam{
+	ctx.RegisterFunc("import", NewGolangFunctor(importFunc), TypeAny, []ExprFuncParam{
 		NewFuncParamFlag(ParamFilepath, PfRepeat),
 	})
-	ctx.RegisterFunc("importAll", NewGolangFunctor2(importAllFunc), TypeAny, []ExprFuncParam{
+	ctx.RegisterFunc("importAll", NewGolangFunctor(importAllFunc), TypeAny, []ExprFuncParam{
 		NewFuncParamFlag(ParamFilepath, PfRepeat),
 	})
 }
diff --git a/builtin-iterator.go b/builtin-iterator.go
index d99f367..2156143 100644
--- a/builtin-iterator.go
+++ b/builtin-iterator.go
@@ -61,7 +61,7 @@ func runFunc(ctx ExprContext, name string, args map[string]any) (result any, err
 	if it, op, err = parseRunArgs(localCtx, args); err != nil {
 		return
 	} else if op == nil {
-		op = NewGolangFunctor2(printLnFunc)
+		op = NewGolangFunctor(printLnFunc)
 		usingDefaultOp = true
 	}
 
@@ -92,7 +92,7 @@ func runFunc(ctx ExprContext, name string, args map[string]any) (result any, err
 }
 
 func ImportIterFuncs(ctx ExprContext) {
-	ctx.RegisterFunc("run", NewGolangFunctor2(runFunc), TypeAny, []ExprFuncParam{
+	ctx.RegisterFunc("run", NewGolangFunctor(runFunc), TypeAny, []ExprFuncParam{
 		NewFuncParam(ParamIterator),
 		NewFuncParamFlag(iterParamOperator, PfOptional),
 		NewFuncParamFlag(iterParamVars, PfOptional),
diff --git a/builtin-math-arith.go b/builtin-math-arith.go
index baf7a46..7be529c 100644
--- a/builtin-math-arith.go
+++ b/builtin-math-arith.go
@@ -169,11 +169,11 @@ func mulFunc(ctx ExprContext, name string, args map[string]any) (result any, err
 }
 
 func ImportMathFuncs(ctx ExprContext) {
-	ctx.RegisterFunc("add", NewGolangFunctor2(addFunc), TypeNumber, []ExprFuncParam{
+	ctx.RegisterFunc("add", NewGolangFunctor(addFunc), TypeNumber, []ExprFuncParam{
 		NewFuncParamFlagDef(ParamValue, PfDefault|PfRepeat, int64(0)),
 	})
 
-	ctx.RegisterFunc("mul", NewGolangFunctor2(mulFunc), TypeNumber, []ExprFuncParam{
+	ctx.RegisterFunc("mul", NewGolangFunctor(mulFunc), TypeNumber, []ExprFuncParam{
 		NewFuncParamFlagDef(ParamValue, PfDefault|PfRepeat, int64(1)),
 	})
 }
diff --git a/builtin-os-file.go b/builtin-os-file.go
index fa377f1..1407dbc 100644
--- a/builtin-os-file.go
+++ b/builtin-os-file.go
@@ -221,33 +221,33 @@ func fileReadTextAllFunc(ctx ExprContext, name string, args map[string]any) (res
 }
 
 func ImportOsFuncs(ctx ExprContext) {
-	ctx.RegisterFunc("fileOpen", NewGolangFunctor2(openFileFunc), TypeFileHandle, []ExprFuncParam{
+	ctx.RegisterFunc("fileOpen", NewGolangFunctor(openFileFunc), TypeFileHandle, []ExprFuncParam{
 		NewFuncParam(ParamFilepath),
 	})
 
-	ctx.RegisterFunc("fileAppend", NewGolangFunctor2(appendFileFunc), TypeFileHandle, []ExprFuncParam{
+	ctx.RegisterFunc("fileAppend", NewGolangFunctor(appendFileFunc), TypeFileHandle, []ExprFuncParam{
 		NewFuncParam(ParamFilepath),
 	})
 
-	ctx.RegisterFunc("fileCreate", NewGolangFunctor2(createFileFunc), TypeFileHandle, []ExprFuncParam{
+	ctx.RegisterFunc("fileCreate", NewGolangFunctor(createFileFunc), TypeFileHandle, []ExprFuncParam{
 		NewFuncParam(ParamFilepath),
 	})
 
-	ctx.RegisterFunc("fileClose", NewGolangFunctor2(closeFileFunc), TypeBoolean, []ExprFuncParam{
+	ctx.RegisterFunc("fileClose", NewGolangFunctor(closeFileFunc), TypeBoolean, []ExprFuncParam{
 		NewFuncParam(ParamHandle),
 	})
 
-	ctx.RegisterFunc("fileWriteText", NewGolangFunctor2(fileWriteTextFunc), TypeInt, []ExprFuncParam{
+	ctx.RegisterFunc("fileWriteText", NewGolangFunctor(fileWriteTextFunc), TypeInt, []ExprFuncParam{
 		NewFuncParam(ParamHandle),
 		NewFuncParamFlagDef(ParamItem, PfDefault|PfRepeat, ""),
 	})
 
-	ctx.RegisterFunc("fileReadText", NewGolangFunctor2(fileReadTextFunc), TypeString, []ExprFuncParam{
+	ctx.RegisterFunc("fileReadText", NewGolangFunctor(fileReadTextFunc), TypeString, []ExprFuncParam{
 		NewFuncParam(ParamHandle),
 		NewFuncParamFlagDef(osLimitCh, PfDefault, "\n"),
 	})
 
-	ctx.RegisterFunc("fileReadTextAll", NewGolangFunctor2(fileReadTextAllFunc), TypeString, []ExprFuncParam{
+	ctx.RegisterFunc("fileReadTextAll", NewGolangFunctor(fileReadTextAllFunc), TypeString, []ExprFuncParam{
 		NewFuncParam(ParamHandle),
 	})
 }
diff --git a/builtin-string.go b/builtin-string.go
index b2bf35c..6a9df5c 100644
--- a/builtin-string.go
+++ b/builtin-string.go
@@ -204,34 +204,34 @@ func splitStrFunc(ctx ExprContext, name string, args map[string]any) (result any
 
 // Import above functions in the context
 func ImportStringFuncs(ctx ExprContext) {
-	ctx.RegisterFunc("strJoin", NewGolangFunctor2(joinStrFunc), TypeString, []ExprFuncParam{
+	ctx.RegisterFunc("strJoin", NewGolangFunctor(joinStrFunc), TypeString, []ExprFuncParam{
 		NewFuncParam(ParamSeparator),
 		NewFuncParamFlag(ParamItem, PfRepeat),
 	})
 
-	ctx.RegisterFunc("strSub", NewGolangFunctor2(subStrFunc), TypeString, []ExprFuncParam{
+	ctx.RegisterFunc("strSub", NewGolangFunctor(subStrFunc), TypeString, []ExprFuncParam{
 		NewFuncParam(ParamSource),
 		NewFuncParamFlagDef(ParamStart, PfDefault, int64(0)),
 		NewFuncParamFlagDef(ParamCount, PfDefault, int64(-1)),
 	})
 
-	ctx.RegisterFunc("strSplit", NewGolangFunctor2(splitStrFunc), "list of "+TypeString, []ExprFuncParam{
+	ctx.RegisterFunc("strSplit", NewGolangFunctor(splitStrFunc), "list of "+TypeString, []ExprFuncParam{
 		NewFuncParam(ParamSource),
 		NewFuncParamFlagDef(ParamSeparator, PfDefault, ""),
 		NewFuncParamFlagDef(ParamCount, PfDefault, int64(-1)),
 	})
 
-	ctx.RegisterFunc("strTrim", NewGolangFunctor2(trimStrFunc), TypeString, []ExprFuncParam{
+	ctx.RegisterFunc("strTrim", NewGolangFunctor(trimStrFunc), TypeString, []ExprFuncParam{
 		NewFuncParam(ParamSource),
 	})
 
-	ctx.RegisterFunc("strStartsWith", NewGolangFunctor2(startsWithStrFunc), TypeBoolean, []ExprFuncParam{
+	ctx.RegisterFunc("strStartsWith", NewGolangFunctor(startsWithStrFunc), TypeBoolean, []ExprFuncParam{
 		NewFuncParam(ParamSource),
 		NewFuncParam(ParamPrefix),
 		NewFuncParamFlag(strParamOther, PfRepeat),
 	})
 
-	ctx.RegisterFunc("strEndsWith", NewGolangFunctor2(endsWithStrFunc), TypeBoolean, []ExprFuncParam{
+	ctx.RegisterFunc("strEndsWith", NewGolangFunctor(endsWithStrFunc), TypeBoolean, []ExprFuncParam{
 		NewFuncParam(ParamSource),
 		NewFuncParam(ParamSuffix),
 		NewFuncParamFlag(strParamOther, PfRepeat),
diff --git a/common-errors.go b/common-errors.go
index 5e11e92..23ebe6f 100644
--- a/common-errors.go
+++ b/common-errors.go
@@ -59,6 +59,10 @@ func ErrWrongParamType(funcName, paramName, paramType string, paramValue any) er
 	return fmt.Errorf("%s(): the %q parameter must be a %s, got a %s (%v)", funcName, paramName, paramType, TypeName(paramValue), paramValue)
 }
 
+func ErrUnknownParam(funcName, paramName string) error {
+	return fmt.Errorf("%s(): unknown parameter %q", funcName, paramName)
+}
+
 // --- Operator errors
 
 func ErrLeftOperandMustBeVariable(leftTerm, opTerm *term) error {
diff --git a/helpers.go b/helpers.go
index 6e16066..f25fa10 100644
--- a/helpers.go
+++ b/helpers.go
@@ -38,7 +38,7 @@ func EvalStringV(source string, args []Arg) (result any, err error) {
 	for _, arg := range args {
 		if isFunc(arg.Value) {
 			if f, ok := arg.Value.(FuncTemplate); ok {
-				functor := NewGolangFunctor2(f)
+				functor := NewGolangFunctor(f)
 				// ctx.RegisterFunc(arg.Name, functor, 0, -1)
 				ctx.RegisterFunc(arg.Name, functor, TypeAny, []ExprFuncParam{
 					NewFuncParamFlagDef(ParamValue, PfDefault|PfRepeat, 0),
diff --git a/iterator.go b/iterator.go
index 52feefc..9b0bc60 100644
--- a/iterator.go
+++ b/iterator.go
@@ -34,7 +34,7 @@ type Iterator interface {
 type ExtIterator interface {
 	Iterator
 	HasOperation(name string) bool
-	CallOperation(name string, args []any) (value any, err error)
+	CallOperation(name string, args map[string]any) (value any, err error)
 }
 
 func errNoOperation(name string) error {
diff --git a/list-iterator.go b/list-iterator.go
index 2070f8f..4d5f823 100644
--- a/list-iterator.go
+++ b/list-iterator.go
@@ -94,7 +94,7 @@ func (it *ListIterator) HasOperation(name string) bool {
 	return yes
 }
 
-func (it *ListIterator) CallOperation(name string, args []any) (v any, err error) {
+func (it *ListIterator) CallOperation(name string, args map[string]any) (v any, err error) {
 	switch name {
 	case NextName:
 		v, err = it.Next()
diff --git a/operand-func.go b/operand-func.go
index 3e02347..6aa564d 100644
--- a/operand-func.go
+++ b/operand-func.go
@@ -40,7 +40,7 @@ func newFuncCallTerm(tk *Token, args []*term) *term {
 
 func evalFuncCall(ctx ExprContext, opTerm *term) (v any, err error) {
 	name, _ := opTerm.tk.Value.(string)
-	v, err = CallFunction3(ctx, name, opTerm)
+	v, err = CallFunction(ctx, name, opTerm)
 	return
 }
 
diff --git a/operator-dot.go b/operator-dot.go
index ebc849e..e097438 100644
--- a/operator-dot.go
+++ b/operator-dot.go
@@ -32,7 +32,7 @@ func evalDot(ctx ExprContext, opTerm *term) (v any, err error) {
 		if indexTerm.symbol() == SymVariable /*|| indexTerm.symbol() == SymString */ {
 			opName := indexTerm.source()
 			if unboxedValue.HasOperation(opName) {
-				v, err = unboxedValue.CallOperation(opName, []any{})
+				v, err = unboxedValue.CallOperation(opName, map[string]any{})
 			} else {
 				err = indexTerm.Errorf("this iterator do not support the %q command", opName)
 				v = false
diff --git a/t_expr_test.go b/t_expr_test.go
index d285dc9..a995ba3 100644
--- a/t_expr_test.go
+++ b/t_expr_test.go
@@ -43,6 +43,6 @@ func TestExpr(t *testing.T) {
 	}
 	// t.Setenv("EXPR_PATH", ".")
 
-	runTestSuiteSpec(t, section, inputs, 17)
-	// runTestSuite(t, section, inputs)
+	// runTestSuiteSpec(t, section, inputs, 17)
+	runTestSuite(t, section, inputs)
 }
diff --git a/t_funcs_test.go b/t_funcs_test.go
index ff202a9..8f20025 100644
--- a/t_funcs_test.go
+++ b/t_funcs_test.go
@@ -35,8 +35,8 @@ func TestFuncs(t *testing.T) {
 		/*  22 */ {`f=func(a,b){a*2+b}; f(b=2,a=1)`, int64(4), nil},
 		/*  23 */ {`f=func(a=10,b=10){a*2+b}; f(b=1)`, int64(21), nil},
 		/*  24 */ {`f=func(a,b){a*2+b}; f(a=1,2)`, nil, `f(): positional param nr 2 not allowed after named params`},
-//		/*  20 */ {`a=[func(){3}]; a[0]()`, int64(3), nil},
-//		/*  20 */ {`m={}; m["f"]=func(){3}; m["f"]()`, int64(3), nil},
+		//		/*  20 */ {`a=[func(){3}]; a[0]()`, int64(3), nil},
+		//		/*  20 */ {`m={}; m["f"]=func(){3}; m["f"]()`, int64(3), nil},
 		// /*  18 */ {`f=func(a){a*2}`, nil, errors.New(`[1:24] expected "function-param-value", got ")"`)},
 	}
 
@@ -51,7 +51,7 @@ func dummy(ctx ExprContext, name string, args map[string]any) (result any, err e
 }
 
 func TestFunctionToStringSimple(t *testing.T) {
-	source := NewGolangFunctor2(dummy)
+	source := NewGolangFunctor(dummy)
 	want := "func(){}"
 	got := source.ToString(0)
 	if got != want {
@@ -59,9 +59,8 @@ func TestFunctionToStringSimple(t *testing.T) {
 	}
 }
 
-
 func TestFunctionGetFunc(t *testing.T) {
-	source := NewGolangFunctor2(dummy)
+	source := NewGolangFunctor(dummy)
 	want := ExprFunc(nil)
 	got := source.GetFunc()
 	if got != want {
diff --git a/t_iterator_test.go b/t_iterator_test.go
index 238f301..bfd6f51 100644
--- a/t_iterator_test.go
+++ b/t_iterator_test.go
@@ -27,6 +27,6 @@ func TestIteratorParser(t *testing.T) {
 		/*  16 */ {`include "test-resources/filter.expr"; it=$(ds,10); it++`, int64(2), nil},
 	}
 
-	// runTestSuiteSpec(t, section, inputs, 7)
+	// runTestSuiteSpec(t, section, inputs, 11)
 	runTestSuite(t, section, inputs)
 }