diff --git a/common-errors.go b/common-errors.go
index b28007f..c4f6048 100644
--- a/common-errors.go
+++ b/common-errors.go
@@ -25,11 +25,11 @@ func errTooMuchParams(funcName string, maxArgs, argCount int) (err error) {
 // --- General errors
 
 func errCantConvert(funcName string, value any, kind string) error {
-	return fmt.Errorf("%s(): can't convert %s to %s", funcName, typeName(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 %s (%v)", funcName, kind, typeName(value), value)
+	return fmt.Errorf("%s() expected %s, got %s (%v)", funcName, kind, TypeName(value), value)
 }
 
 func errFuncDivisionByZero(funcName string) error {
@@ -47,9 +47,9 @@ func errMissingRequiredParameter(funcName, paramName string) error {
 }
 
 func errInvalidParameterValue(funcName, paramName string, paramValue any) error {
-	return fmt.Errorf("%s() invalid value %s (%v) for parameter %q", funcName, typeName(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 %s (%v)", funcName, paramName, paramType, typeName(paramValue), paramValue)
+	return fmt.Errorf("%s() the %q parameter must be a %s, got a %s (%v)", funcName, paramName, paramType, TypeName(paramValue), paramValue)
 }
diff --git a/formatter.go b/formatter.go
index be0d911..120cd86 100644
--- a/formatter.go
+++ b/formatter.go
@@ -51,7 +51,7 @@ type Typer interface {
 	TypeName() string
 }
 
-func typeName(v any) (name string) {
+func TypeName(v any) (name string) {
 	if v == nil {
 		name = "nil"
 	} else if typer, ok := v.(Typer); ok {
diff --git a/import-utils.go b/import-utils.go
index ee1e1b5..10700d6 100644
--- a/import-utils.go
+++ b/import-utils.go
@@ -20,7 +20,7 @@ const (
 
 func checkStringParamExpected(funcName string, paramValue any, paramPos int) (err error) {
 	if !(IsString(paramValue) /*|| isList(paramValue)*/) {
-		err = fmt.Errorf("%s(): param nr %d has wrong type %s, string expected", funcName, paramPos+1, typeName(paramValue))
+		err = fmt.Errorf("%s(): param nr %d has wrong type %s, string expected", funcName, paramPos+1, TypeName(paramValue))
 	}
 	return
 }
diff --git a/operator-assign.go b/operator-assign.go
index 9aed2f1..f964364 100644
--- a/operator-assign.go
+++ b/operator-assign.go
@@ -28,7 +28,7 @@ func assignCollectionItem(ctx ExprContext, collectionTerm, keyListTerm *term, va
 	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))
+		err = keyListTerm.Errorf("index/key specification expected, got %v [%s]", keyListValue, TypeName(keyListValue))
 		return
 	}
 	if keyValue = (*keyList)[0]; keyValue == nil {
@@ -41,7 +41,7 @@ func assignCollectionItem(ctx ExprContext, collectionTerm, keyListTerm *term, va
 		if index, ok := keyValue.(int64); ok {
 			err = collection.setItem(index, value)
 		} else {
-			err = keyListTerm.Errorf("integer expected, got %v [%s]", keyValue, typeName(keyValue))
+			err = keyListTerm.Errorf("integer expected, got %v [%s]", keyValue, TypeName(keyValue))
 		}
 	case *DictType:
 		err = collection.setItem(keyValue, value)
diff --git a/operator-builtin.go b/operator-builtin.go
index edda8a2..c5ab462 100644
--- a/operator-builtin.go
+++ b/operator-builtin.go
@@ -41,7 +41,7 @@ func evalBuiltin(ctx ExprContext, self *term) (v any, err error) {
 					break
 				}
 			} else {
-				err = self.Errorf("expected string at item nr %d, got %s", it.Index()+1, typeName(moduleSpec))
+				err = self.Errorf("expected string at item nr %d, got %s", it.Index()+1, TypeName(moduleSpec))
 				break
 			}
 		}
diff --git a/operator-plugin.go b/operator-plugin.go
index aae417c..786bc1a 100644
--- a/operator-plugin.go
+++ b/operator-plugin.go
@@ -38,7 +38,7 @@ func evalPlugin(ctx ExprContext, self *term) (v any, err error) {
 			}
 			count++
 		} else {
-			err = self.Errorf("expected string as item nr %d, got %s", it.Index()+1, typeName(moduleSpec))
+			err = self.Errorf("expected string as item nr %d, got %s", it.Index()+1, TypeName(moduleSpec))
 			break
 		}
 	}
diff --git a/t_parser_test.go b/t_parser_test.go
index 1f4752a..f85d9e9 100644
--- a/t_parser_test.go
+++ b/t_parser_test.go
@@ -203,7 +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 [%s], want = %v [%s]", count, input.source, gotResult, typeName(gotResult), input.wantResult, typeName(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
 	}
 
diff --git a/term.go b/term.go
index fae9b58..73df20f 100644
--- a/term.go
+++ b/term.go
@@ -156,15 +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 %s (%v)", valueDescription, typeName(computedValue), computedValue)
+		err = self.Errorf("%s, got %s (%v)", valueDescription, TypeName(computedValue), computedValue)
 	}
 	return
 }
 
 func (self *term) errIncompatibleTypes(leftValue, rightValue any) error {
-	leftType := typeName(leftValue)
+	leftType := TypeName(leftValue)
 	leftText := getFormatted(leftValue, Truncate)
-	rightType := typeName(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",
@@ -176,7 +176,7 @@ 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' [%s]",
-		self.source(), value, typeName(value))
+		self.source(), value, TypeName(value))
 }
 
 func (self *term) Errorf(template string, args ...any) (err error) {
diff --git a/utils.go b/utils.go
index a82f3b3..c07ed98 100644
--- a/utils.go
+++ b/utils.go
@@ -207,7 +207,7 @@ func toInt(value any, description string) (i int, err error) {
 	} else if valueInt, ok := value.(int); ok {
 		i = valueInt
 	} else {
-		err = fmt.Errorf("%s expected integer, got %s (%v)", description, typeName(value), value)
+		err = fmt.Errorf("%s expected integer, got %s (%v)", description, TypeName(value), value)
 	}
 	return
 }