From 5285b6132095f2fee05fbad7478f370ff05325d5 Mon Sep 17 00:00:00 2001
From: Celestino Amoroso <celestino.amoroso@gmail.com>
Date: Sat, 9 May 2026 10:34:46 +0200
Subject: [PATCH] 'join' operator renamed as 'cat'

---
 operator-join.go => operator-cat.go | 12 ++++++------
 scan/symbol.go                      |  2 ++
 t_operator_test.go                  |  8 ++++----
 3 files changed, 12 insertions(+), 10 deletions(-)
 rename operator-join.go => operator-cat.go (84%)

diff --git a/operator-join.go b/operator-cat.go
similarity index 84%
rename from operator-join.go
rename to operator-cat.go
index 3765e12..25ea85a 100644
--- a/operator-join.go
+++ b/operator-cat.go
@@ -1,7 +1,7 @@
 // Copyright (c) 2024-2026 Celestino Amoroso (celestino.amoroso@gmail.com).
 // All rights reserved.
 
-// operator-join.go
+// operator-cat.go
 package expr
 
 import (
@@ -12,19 +12,19 @@ import (
 	"git.portale-stac.it/go-pkg/expr/scan"
 )
 
-//-------- join term
+//-------- cat term
 
-func newJoinTerm(tk *scan.Token) (inst *scan.Term) {
+func newCatTerm(tk *scan.Token) (inst *scan.Term) {
 	return &scan.Term{
 		Tk:       *tk,
 		Children: make([]*scan.Term, 0, 2),
 		Position: scan.PosInfix,
 		Priority: scan.PriIterOp,
-		EvalFunc: evalJoin,
+		EvalFunc: evalCat,
 	}
 }
 
-func evalJoin(ctx kern.ExprContext, opTerm *scan.Term) (v any, err error) {
+func evalCat(ctx kern.ExprContext, opTerm *scan.Term) (v any, err error) {
 	var leftValue, rightValue any
 	var itLeft, itRight kern.Iterator
 	var item any
@@ -69,5 +69,5 @@ func evalJoin(ctx kern.ExprContext, opTerm *scan.Term) (v any, err error) {
 
 // init
 func init() {
-	scan.RegisterTermConstructor(scan.SymKwJoin, newJoinTerm)
+	scan.RegisterTermConstructor(scan.SymKwCat, newCatTerm)
 }
diff --git a/scan/symbol.go b/scan/symbol.go
index 34056dc..ee45309 100644
--- a/scan/symbol.go
+++ b/scan/symbol.go
@@ -122,6 +122,7 @@ const (
 	SymKwMap
 	SymKwFilter
 	SymKwDigest
+	SymKwCat
 	SymKwGroupBy
 	SymKwJoin
 	SymKwNil
@@ -141,6 +142,7 @@ func init() {
 		"IN":      SymKwIn,
 		"INCLUDE": SymKwInclude,
 		"MAP":     SymKwMap,
+		"CAT":     SymKwCat,
 		"FILTER":  SymKwFilter,
 		"NOT":     SymKwNot,
 		"OR":      SymKwOr,
diff --git a/t_operator_test.go b/t_operator_test.go
index 1edcd3d..e83bb4c 100644
--- a/t_operator_test.go
+++ b/t_operator_test.go
@@ -75,11 +75,11 @@ func TestOperatorDigest(t *testing.T) {
 	runTestSuite(t, section, inputs)
 }
 
-func TestOperatorJoin(t *testing.T) {
-	section := "Operator-Join"
+func TestOperatorCat(t *testing.T) {
+	section := "Operator-Cat"
 	inputs := []inputType{
-		/*   1 */ {`["a","b"] join ["x"]`, kern.NewList([]any{"a", "b", "x"}), nil},
-		/*   2 */ {`["a","b"] join ["x"-true]`, nil, `[1:21] left operand 'x' [string] and right operand 'true' [bool] are not compatible with operator "-"`},
+		/*   1 */ {`["a","b"] cat ["x"]`, kern.NewList([]any{"a", "b", "x"}), nil},
+		/*   2 */ {`["a","b"] cat ["x"-true]`, nil, `[1:20] left operand 'x' [string] and right operand 'true' [bool] are not compatible with operator "-"`},
 	}
 
 	// runTestSuiteSpec(t, section, inputs, 2)