diff --git a/builtin-base.go b/builtin-base.go
index 45b89ce..acedefa 100644
--- a/builtin-base.go
+++ b/builtin-base.go
@@ -43,7 +43,7 @@ func isStringFunc(ctx kern.ExprContext, name string, args map[string]any) (resul
 }
 
 func isFractionFunc(ctx kern.ExprContext, name string, args map[string]any) (result any, err error) {
-	result = kern.IsFract(args[kern.ParamValue])
+	result = kern.IsFraction(args[kern.ParamValue])
 	return
 }
 
diff --git a/helpers.go b/helpers.go
index 49922de..cc8df30 100644
--- a/helpers.go
+++ b/helpers.go
@@ -11,6 +11,7 @@ import (
 	"strings"
 
 	"git.portale-stac.it/go-pkg/expr/kern"
+	"git.portale-stac.it/go-pkg/expr/util"
 )
 
 func EvalString(ctx kern.ExprContext, source string) (result any, err error) {
@@ -38,7 +39,7 @@ func EvalStringA(source string, args ...Arg) (result any, err error) {
 func EvalStringV(source string, args []Arg) (result any, err error) {
 	ctx := NewSimpleStoreWithoutGlobalContext()
 	for _, arg := range args {
-		if kern.IsFunc(arg.Value) {
+		if util.IsFunc(arg.Value) {
 			if f, ok := arg.Value.(kern.FuncTemplate); ok {
 				functor := kern.NewGolangFunctor(f)
 				// ctx.RegisterFunc(arg.Name, functor, 0, -1)
diff --git a/import-utils.go b/import-utils.go
index 0d0d766..75eddd3 100644
--- a/import-utils.go
+++ b/import-utils.go
@@ -13,6 +13,7 @@ import (
 	"strings"
 
 	"git.portale-stac.it/go-pkg/expr/kern"
+	"git.portale-stac.it/go-pkg/expr/util"
 )
 
 const (
@@ -85,7 +86,7 @@ func searchAmongPath(filename string, dirList []string) (filePath string) {
 	}
 
 	for _, dir := range dirList {
-		if dir, err = kern.ExpandPath(dir); err != nil {
+		if dir, err = util.ExpandPath(dir); err != nil {
 			continue
 		}
 		if fullPath := path.Join(dir, filename); isFile(fullPath) {
@@ -108,7 +109,7 @@ func isPathRelative(filePath string) bool {
 }
 
 func makeFilepath(filename string, dirList []string) (filePath string, err error) {
-	if filename, err = kern.ExpandPath(filename); err != nil {
+	if filename, err = util.ExpandPath(filename); err != nil {
 		return
 	}
 
diff --git a/kern/bool.go b/kern/bool.go
new file mode 100644
index 0000000..868d982
--- /dev/null
+++ b/kern/bool.go
@@ -0,0 +1,27 @@
+// Copyright (c) 2024-2026 Celestino Amoroso (celestino.amoroso@gmail.com).
+// All rights reserved.
+
+// string.go
+package kern
+
+func IsBool(v any) (ok bool) {
+	_, ok = v.(bool)
+	return ok
+}
+
+func ToBool(v any) (b bool, ok bool) {
+	ok = true
+	switch x := v.(type) {
+	case string:
+		b = len(x) > 0
+	case float64:
+		b = x != 0.0
+	case int64:
+		b = x != 0
+	case bool:
+		b = x
+	default:
+		ok = false
+	}
+	return
+}
diff --git a/kern/dict-type.go b/kern/dict-type.go
index 94c67fe..bfb4473 100644
--- a/kern/dict-type.go
+++ b/kern/dict-type.go
@@ -12,6 +12,11 @@ import (
 
 type DictType map[any]any
 
+func IsDict(v any) (ok bool) {
+	_, ok = v.(*DictType)
+	return ok
+}
+
 func MakeDict() (dict *DictType) {
 	d := make(DictType)
 	dict = &d
diff --git a/kern/float.go b/kern/float.go
new file mode 100644
index 0000000..813e93d
--- /dev/null
+++ b/kern/float.go
@@ -0,0 +1,23 @@
+// Copyright (c) 2024-2026 Celestino Amoroso (celestino.amoroso@gmail.com).
+// All rights reserved.
+
+// float.go
+package kern
+
+func IsFloat(v any) (ok bool) {
+	_, ok = v.(float64)
+	return ok
+}
+
+func AnyFloat(v any) (float float64, ok bool) {
+	ok = true
+	switch floatval := v.(type) {
+	case float32:
+		float = float64(floatval)
+	case float64:
+		float = floatval
+	default:
+		ok = false
+	}
+	return
+}
diff --git a/kern/fraction-type.go b/kern/fraction-type.go
index 290d402..63ec354 100644
--- a/kern/fraction-type.go
+++ b/kern/fraction-type.go
@@ -367,3 +367,15 @@ func IsFraction(v any) (ok bool) {
 	_, ok = v.(*FractionType)
 	return ok
 }
+
+// func IsFract(v any) (ok bool) {
+// 	_, ok = v.(*FractionType)
+// 	return ok
+// }
+
+func IsRational(v any) (ok bool) {
+	if _, ok = v.(*FractionType); !ok {
+		_, ok = v.(int64)
+	}
+	return ok
+}
diff --git a/kern/function.go b/kern/function.go
index 9cfb948..32a0d51 100644
--- a/kern/function.go
+++ b/kern/function.go
@@ -14,6 +14,11 @@ type FuncTemplate func(ctx ExprContext, name string, args map[string]any) (resul
 
 type DeepFuncTemplate func(a, b any) (eq bool, err error)
 
+func IsFunctor(v any) (ok bool) {
+	_, ok = v.(Functor)
+	return
+}
+
 // ---- Common functor definition
 type BaseFunctor struct {
 	info ExprFunc
diff --git a/kern/iterator.go b/kern/iterator.go
index 207fab1..b61f0a4 100644
--- a/kern/iterator.go
+++ b/kern/iterator.go
@@ -45,3 +45,8 @@ type ExtIterator interface {
 func ErrNoOperation(name string) error {
 	return fmt.Errorf("no %s() function defined in the data-source", name)
 }
+
+func IsIterator(v any) (ok bool) {
+	_, ok = v.(Iterator)
+	return
+}
diff --git a/kern/list-type.go b/kern/list-type.go
index eefbf26..bf23fd3 100644
--- a/kern/list-type.go
+++ b/kern/list-type.go
@@ -12,6 +12,11 @@ import (
 
 type ListType []any
 
+func IsList(v any) (ok bool) {
+	_, ok = v.(*ListType)
+	return ok
+}
+
 func NewListA(listAny ...any) (list *ListType) {
 	if listAny == nil {
 		listAny = []any{}
diff --git a/kern/number.go b/kern/number.go
new file mode 100644
index 0000000..a8c4f00
--- /dev/null
+++ b/kern/number.go
@@ -0,0 +1,77 @@
+// Copyright (c) 2024-2026 Celestino Amoroso (celestino.amoroso@gmail.com).
+// All rights reserved.
+
+// number.go
+package kern
+
+import (
+	"fmt"
+)
+
+func IsInteger(v any) (ok bool) {
+	_, ok = v.(int64)
+	return ok
+}
+
+func IsNumber(v any) (ok bool) {
+	return IsFloat(v) || IsInteger(v)
+}
+
+func IsNumOrFract(v any) (ok bool) {
+	return IsFloat(v) || IsInteger(v) || IsFraction(v)
+}
+
+func IsNumberString(v any) (ok bool) {
+	return IsString(v) || IsNumber(v)
+}
+
+func NumAsFloat(v any) (f float64) {
+	var ok bool
+	if f, ok = v.(float64); !ok {
+		if fract, ok := v.(*FractionType); ok {
+			f = fract.ToFloat()
+		} else {
+			i, _ := v.(int64)
+			f = float64(i)
+		}
+	}
+	return
+}
+
+func AnyInteger(v any) (i int64, ok bool) {
+	ok = true
+	switch intval := v.(type) {
+	case int:
+		i = int64(intval)
+	case uint8:
+		i = int64(intval)
+	case uint16:
+		i = int64(intval)
+	case uint64:
+		i = int64(intval)
+	case uint32:
+		i = int64(intval)
+	case int8:
+		i = int64(intval)
+	case int16:
+		i = int64(intval)
+	case int32:
+		i = int64(intval)
+	case int64:
+		i = intval
+	default:
+		ok = false
+	}
+	return
+}
+
+func ToGoInt(value any, description string) (i int, err error) {
+	if valueInt64, ok := value.(int64); ok {
+		i = int(valueInt64)
+	} else if valueInt, ok := value.(int); ok {
+		i = valueInt
+	} else {
+		err = fmt.Errorf("%s expected integer, got %s (%v)", description, TypeName(value), value)
+	}
+	return
+}
diff --git a/kern/string.go b/kern/string.go
new file mode 100644
index 0000000..00f48d8
--- /dev/null
+++ b/kern/string.go
@@ -0,0 +1,23 @@
+// Copyright (c) 2024-2026 Celestino Amoroso (celestino.amoroso@gmail.com).
+// All rights reserved.
+
+// string.go
+package kern
+
+import (
+	"fmt"
+)
+
+func IsString(v any) (ok bool) {
+	_, ok = v.(string)
+	return ok
+}
+
+func ToGoString(value any, description string) (s string, err error) {
+	if s, ok := value.(string); ok {
+		return s, nil
+	} else {
+		err = fmt.Errorf("%s expected string, got %s (%v)", description, TypeName(value), value)
+	}
+	return
+}
diff --git a/kern/utils.go b/kern/utils.go
deleted file mode 100644
index 1758bf2..0000000
--- a/kern/utils.go
+++ /dev/null
@@ -1,232 +0,0 @@
-// Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
-// All rights reserved.
-
-// utils.go
-package kern
-
-import (
-	"fmt"
-	"reflect"
-)
-
-func IsString(v any) (ok bool) {
-	_, ok = v.(string)
-	return ok
-}
-
-func IsInteger(v any) (ok bool) {
-	_, ok = v.(int64)
-	return ok
-}
-
-func IsFloat(v any) (ok bool) {
-	_, ok = v.(float64)
-	return ok
-}
-
-func IsBool(v any) (ok bool) {
-	_, ok = v.(bool)
-	return ok
-}
-
-func IsList(v any) (ok bool) {
-	_, ok = v.(*ListType)
-	return ok
-}
-
-func IsDict(v any) (ok bool) {
-	_, ok = v.(*DictType)
-	return ok
-}
-
-func IsFract(v any) (ok bool) {
-	_, ok = v.(*FractionType)
-	return ok
-}
-
-func IsRational(v any) (ok bool) {
-	if _, ok = v.(*FractionType); !ok {
-		_, ok = v.(int64)
-	}
-	return ok
-}
-
-func IsNumber(v any) (ok bool) {
-	return IsFloat(v) || IsInteger(v)
-}
-
-func IsNumOrFract(v any) (ok bool) {
-	return IsFloat(v) || IsInteger(v) || IsFraction(v)
-}
-
-func IsNumberString(v any) (ok bool) {
-	return IsString(v) || IsNumber(v)
-}
-
-func IsFunctor(v any) (ok bool) {
-	_, ok = v.(Functor)
-	return
-}
-
-func IsIterator(v any) (ok bool) {
-	_, ok = v.(Iterator)
-	return
-}
-
-func NumAsFloat(v any) (f float64) {
-	var ok bool
-	if f, ok = v.(float64); !ok {
-		if fract, ok := v.(*FractionType); ok {
-			f = fract.ToFloat()
-		} else {
-			i, _ := v.(int64)
-			f = float64(i)
-		}
-	}
-	return
-}
-
-func ToBool(v any) (b bool, ok bool) {
-	ok = true
-	switch x := v.(type) {
-	case string:
-		b = len(x) > 0
-	case float64:
-		b = x != 0.0
-	case int64:
-		b = x != 0
-	case bool:
-		b = x
-	default:
-		ok = false
-	}
-	return
-}
-
-func IsFunc(v any) bool {
-	return reflect.TypeOf(v).Kind() == reflect.Func
-}
-
-func AnyInteger(v any) (i int64, ok bool) {
-	ok = true
-	switch intval := v.(type) {
-	case int:
-		i = int64(intval)
-	case uint8:
-		i = int64(intval)
-	case uint16:
-		i = int64(intval)
-	case uint64:
-		i = int64(intval)
-	case uint32:
-		i = int64(intval)
-	case int8:
-		i = int64(intval)
-	case int16:
-		i = int64(intval)
-	case int32:
-		i = int64(intval)
-	case int64:
-		i = intval
-	default:
-		ok = false
-	}
-	return
-}
-
-func FromGenericAny(v any) (exprAny any, ok bool) {
-	if v != nil {
-		if exprAny, ok = v.(bool); ok {
-			return
-		}
-		if exprAny, ok = v.(string); ok {
-			return
-		}
-		if exprAny, ok = AnyInteger(v); ok {
-			return
-		}
-		if exprAny, ok = AnyFloat(v); ok {
-			return
-		}
-		if exprAny, ok = v.(*DictType); ok {
-			return
-		}
-		if exprAny, ok = v.(*ListType); ok {
-			return
-		}
-	}
-	return
-}
-
-func AnyFloat(v any) (float float64, ok bool) {
-	ok = true
-	switch floatval := v.(type) {
-	case float32:
-		float = float64(floatval)
-	case float64:
-		float = floatval
-	default:
-		ok = false
-	}
-	return
-}
-
-func CopyMap[K comparable, V any](dest, source map[K]V) map[K]V {
-	for k, v := range source {
-		dest[k] = v
-	}
-	return dest
-}
-
-// func CloneMap[K comparable, V any](source map[K]V) map[K]V {
-// 	dest := make(map[K]V, len(source))
-// 	return CopyMap(dest, source)
-// }
-
-func CopyFilteredMap[K comparable, V any](dest, source map[K]V, filter func(key K) (accept bool)) map[K]V {
-	// fmt.Printf("--- Clone with filter %p\n", filter)
-	if filter == nil {
-		return CopyMap(dest, source)
-	} else {
-		for k, v := range source {
-			if filter(k) {
-				// fmt.Printf("\tClone var %q\n", k)
-				dest[k] = v
-			}
-		}
-	}
-	return dest
-}
-
-func CloneFilteredMap[K comparable, V any](source map[K]V, filter func(key K) (accept bool)) map[K]V {
-	dest := make(map[K]V, len(source))
-	return CopyFilteredMap(dest, source, filter)
-}
-
-func ToGoInt(value any, description string) (i int, err error) {
-	if valueInt64, ok := value.(int64); ok {
-		i = int(valueInt64)
-	} else if valueInt, ok := value.(int); ok {
-		i = valueInt
-	} else {
-		err = fmt.Errorf("%s expected integer, got %s (%v)", description, TypeName(value), value)
-	}
-	return
-}
-
-func ToGoString(value any, description string) (s string, err error) {
-	if s, ok := value.(string); ok {
-		return s, nil
-	} else {
-		err = fmt.Errorf("%s expected string, got %s (%v)", description, TypeName(value), value)
-	}
-	return
-}
-
-func ForAll[T, V any](ts []T, fn func(T) V) []V {
-	result := make([]V, len(ts))
-	for i, t := range ts {
-		result[i] = fn(t)
-	}
-	return result
-}
diff --git a/operator-assign.go b/operator-assign.go
index 5dcdb4a..492cbb7 100644
--- a/operator-assign.go
+++ b/operator-assign.go
@@ -6,6 +6,7 @@ package expr
 
 import (
 	"git.portale-stac.it/go-pkg/expr/kern"
+	"git.portale-stac.it/go-pkg/expr/util"
 )
 
 //-------- assign term
@@ -84,7 +85,7 @@ func evalAssign(ctx kern.ExprContext, opTerm *term) (v any, err error) {
 				if info := functor.GetFunc(); info != nil {
 					ctx.RegisterFunc(leftTerm.Source(), info.Functor(), info.ReturnType(), info.Params())
 				} else if funcDef, ok := functor.(*exprFunctor); ok {
-					paramSpecs := kern.ForAll(funcDef.params, func(p kern.ExprFuncParam) kern.ExprFuncParam { return p })
+					paramSpecs := util.ForAll(funcDef.params, func(p kern.ExprFuncParam) kern.ExprFuncParam { return p })
 
 					ctx.RegisterFunc(leftTerm.Source(), functor, kern.TypeAny, paramSpecs)
 				} else {
diff --git a/simple-store.go b/simple-store.go
index f5d5768..f72cd9e 100644
--- a/simple-store.go
+++ b/simple-store.go
@@ -9,6 +9,7 @@ import (
 	"slices"
 
 	"git.portale-stac.it/go-pkg/expr/kern"
+	"git.portale-stac.it/go-pkg/expr/util"
 	// "strings"
 )
 
@@ -61,8 +62,8 @@ func (ctx *SimpleStore) GetGlobal() (globalCtx kern.ExprContext) {
 func (ctx *SimpleStore) Clone() kern.ExprContext {
 	clone := &SimpleStore{
 		global:    ctx.global,
-		varStore:  kern.CloneFilteredMap(ctx.varStore, filterRefName),
-		funcStore: kern.CloneFilteredMap(ctx.funcStore, filterRefName),
+		varStore:  util.CloneFilteredMap(ctx.varStore, filterRefName),
+		funcStore: util.CloneFilteredMap(ctx.funcStore, filterRefName),
 	}
 	return clone
 }
@@ -138,7 +139,7 @@ func (ctx *SimpleStore) UnsafeSetVar(varName string, value any) {
 
 func (ctx *SimpleStore) SetVar(varName string, value any) {
 	// fmt.Printf("[%p] SetVar(%v, %v)\n", ctx, varName, value)
-	if allowedValue, ok := kern.FromGenericAny(value); ok {
+	if allowedValue, ok := util.FromGenericAny(value); ok {
 		ctx.varStore[varName] = allowedValue
 	} else {
 		panic(fmt.Errorf("unsupported type %T of value %v", value, value))
diff --git a/t_utils-unix_test.go b/t_utils-unix_test.go
index 75639e6..5d8b6c9 100644
--- a/t_utils-unix_test.go
+++ b/t_utils-unix_test.go
@@ -12,7 +12,7 @@ import (
 	"path"
 	"testing"
 
-	"git.portale-stac.it/go-pkg/expr/kern"
+	"git.portale-stac.it/go-pkg/expr/util"
 )
 
 func TestExpandPathRootOk(t *testing.T) {
@@ -21,7 +21,7 @@ func TestExpandPathRootOk(t *testing.T) {
 	// wantErr := errors.New(`test expected string, got list ([])`)
 	wantErr := error(nil)
 
-	gotValue, gotErr := kern.ExpandPath(source)
+	gotValue, gotErr := util.ExpandPath(source)
 
 	if gotErr != nil && gotErr.Error() != wantErr.Error() {
 		t.Errorf(`ExpandPath(%v) gotValue=%q, gotErr=%v -> wantValue=%q, wantErr=%v`,
@@ -38,7 +38,7 @@ func TestExpandPathRootSubDirOk(t *testing.T) {
 	// wantErr := errors.New(`test expected string, got list ([])`)
 	wantErr := error(nil)
 
-	gotValue, gotErr := kern.ExpandPath(source)
+	gotValue, gotErr := util.ExpandPath(source)
 
 	if gotErr != nil && gotErr.Error() != wantErr.Error() {
 		t.Errorf(`ExpandPath(%v) gotValue=%q, gotErr=%v -> wantValue=%q, wantErr=%v`,
@@ -56,7 +56,7 @@ func TestExpandPathUser(t *testing.T) {
 	// wantErr := errors.New(`test expected string, got list ([])`)
 	wantErr := error(nil)
 
-	gotValue, gotErr := kern.ExpandPath(source)
+	gotValue, gotErr := util.ExpandPath(source)
 
 	if gotErr != nil {
 		t.Errorf(`ExpandPath(%v) gotValue=%q, gotErr=%v -> wantValue=%q, wantErr=%v`,
@@ -74,7 +74,7 @@ func TestExpandPathEnv(t *testing.T) {
 	// wantErr := errors.New(`test expected string, got list ([])`)
 	wantErr := error(nil)
 
-	gotValue, gotErr := kern.ExpandPath(source)
+	gotValue, gotErr := util.ExpandPath(source)
 
 	if gotErr != nil {
 		t.Errorf(`ExpandPath(%v) gotValue=%q, gotErr=%v -> wantValue=%q, wantErr=%v`,
@@ -90,7 +90,7 @@ func TestExpandPathErr(t *testing.T) {
 	wantValue := "~fake-user/test"
 	wantErr := errors.New(`user: unknown user fake-user`)
 
-	gotValue, gotErr := kern.ExpandPath(source)
+	gotValue, gotErr := util.ExpandPath(source)
 
 	if gotErr != nil && gotErr.Error() != wantErr.Error() {
 		t.Errorf(`ExpandPath(%v) gotValue=%q, gotErr=%v -> wantValue=%q, wantErr=%v`,
@@ -108,7 +108,7 @@ func TestExpandPathUserErr(t *testing.T) {
 	// wantErr := errors.New(`test expected string, got list ([])`)
 	wantErr := error(nil)
 
-	gotValue, gotErr := kern.ExpandPath(source)
+	gotValue, gotErr := util.ExpandPath(source)
 
 	if gotErr != nil {
 		t.Errorf(`ExpandPath(%v) gotValue=%q, gotErr=%v -> wantValue=%q, wantErr=%v`,
diff --git a/t_utils_test.go b/t_utils_test.go
index 79dd4dd..3444103 100644
--- a/t_utils_test.go
+++ b/t_utils_test.go
@@ -10,6 +10,7 @@ import (
 	"testing"
 
 	"git.portale-stac.it/go-pkg/expr/kern"
+	"git.portale-stac.it/go-pkg/expr/util"
 )
 
 func TestIsString(t *testing.T) {
@@ -161,7 +162,7 @@ func TestAnyInteger(t *testing.T) {
 func TestCopyMap(t *testing.T) {
 	source := map[string]int{"one": 1, "two": 2, "three": 3}
 	dest := make(map[string]int)
-	result := kern.CopyMap(dest, source)
+	result := util.CopyMap(dest, source)
 	if !reflect.DeepEqual(result, source) {
 		t.Errorf("utils.CopyMap() failed")
 	}
diff --git a/kern/utils-unix.go b/util/utils-unix.go
similarity index 98%
rename from kern/utils-unix.go
rename to util/utils-unix.go
index afd0a35..d1b3728 100644
--- a/kern/utils-unix.go
+++ b/util/utils-unix.go
@@ -4,7 +4,7 @@
 // All rights reserved.
 
 // utils-unix.go
-package kern
+package util
 
 import (
 	"os"
diff --git a/kern/utils-windows.go b/util/utils-windows.go
similarity index 96%
rename from kern/utils-windows.go
rename to util/utils-windows.go
index efad62b..b8336f4 100644
--- a/kern/utils-windows.go
+++ b/util/utils-windows.go
@@ -4,7 +4,7 @@
 // All rights reserved.
 
 // utils-unix.go
-package kern
+package util
 
 import (
 	"os"
diff --git a/util/utils.go b/util/utils.go
new file mode 100644
index 0000000..88b3d7b
--- /dev/null
+++ b/util/utils.go
@@ -0,0 +1,79 @@
+// Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
+// All rights reserved.
+
+// utils.go
+package util
+
+import (
+	"reflect"
+
+	"git.portale-stac.it/go-pkg/expr/kern"
+)
+
+func IsFunc(v any) bool {
+	return reflect.TypeOf(v).Kind() == reflect.Func
+}
+
+func FromGenericAny(v any) (exprAny any, ok bool) {
+	if v != nil {
+		if exprAny, ok = v.(bool); ok {
+			return
+		}
+		if exprAny, ok = v.(string); ok {
+			return
+		}
+		if exprAny, ok = kern.AnyInteger(v); ok {
+			return
+		}
+		if exprAny, ok = kern.AnyFloat(v); ok {
+			return
+		}
+		if exprAny, ok = v.(*kern.DictType); ok {
+			return
+		}
+		if exprAny, ok = v.(*kern.ListType); ok {
+			return
+		}
+	}
+	return
+}
+
+func CopyMap[K comparable, V any](dest, source map[K]V) map[K]V {
+	for k, v := range source {
+		dest[k] = v
+	}
+	return dest
+}
+
+// func CloneMap[K comparable, V any](source map[K]V) map[K]V {
+// 	dest := make(map[K]V, len(source))
+// 	return CopyMap(dest, source)
+// }
+
+func CopyFilteredMap[K comparable, V any](dest, source map[K]V, filter func(key K) (accept bool)) map[K]V {
+	// fmt.Printf("--- Clone with filter %p\n", filter)
+	if filter == nil {
+		return CopyMap(dest, source)
+	} else {
+		for k, v := range source {
+			if filter(k) {
+				// fmt.Printf("\tClone var %q\n", k)
+				dest[k] = v
+			}
+		}
+	}
+	return dest
+}
+
+func CloneFilteredMap[K comparable, V any](source map[K]V, filter func(key K) (accept bool)) map[K]V {
+	dest := make(map[K]V, len(source))
+	return CopyFilteredMap(dest, source, filter)
+}
+
+func ForAll[T, V any](ts []T, fn func(T) V) []V {
+	result := make([]V, len(ts))
+	for i, t := range ts {
+		result[i] = fn(t)
+	}
+	return result
+}