use @ to concat lists

Author: butterunderflow

src/res_core.ml

@@ -451,6 +451,26 @@ let makeListPattern loc seq ext_opt =
   in
   handle_seq seq
 
+let makeListAppend loc seq =
+  let rec handle_seq = function
+    | [] ->
+      let loc = {loc with Location.loc_ghost = true} in
+      let nil = {Location.txt = Longident.Lident "[]"; loc} in
+      Ast_helper.Exp.construct ~loc nil None
+    | [e1] -> e1
+    | e1 :: el ->
+      let exp_el = handle_seq el in
+      let loc =
+        mkLoc e1.Parsetree.pexp_loc.Location.loc_start exp_el.pexp_loc.loc_end
+      in
+      Ast_helper.Exp.apply ~loc
+        (Ast_helper.Exp.ident (Location.mkloc (Longident.Lident "@") loc))
+        [Nolabel, e1;
+         Nolabel, exp_el]
+  in
+  handle_seq seq
+
+
 (* TODO: diagnostic reporting *)
 let lidentOfPath longident =
   match Longident.flatten longident |> List.rev with
@@ -3743,13 +3763,7 @@ and parseListExpr ~startPos p =
   | [(exprs, None, _, _)] -> makeListExpression loc exprs None
   | exprs ->
     let listExprs = List.map make_sub_expr exprs in
-    Ast_helper.Exp.apply ~loc
-      (Ast_helper.Exp.ident ~loc
-         (Location.mkloc
-            (Longident.Ldot
-               (Longident.Ldot (Longident.Lident "Belt", "List"), "concatMany"))
-            loc))
-      [(Asttypes.Nolabel, Ast_helper.Exp.array ~loc listExprs)]
+    makeListAppend loc listExprs
 (* | (true (\* spread expression *\), expr, _) :: exprs ->
  *   let exprs = check_all_non_spread_exp exprs in
  *   makeListExpression loc exprs (Some expr)

src/res_parsetree_viewer.mli

@@ -44,6 +44,10 @@ val collectListExpressions :
   Parsetree.expression ->
   Parsetree.expression list * Parsetree.expression option
 
+val collectConcatListExpressions :
+  Parsetree.expression ->
+  (Parsetree.expression list * Parsetree.expression option) list
+
 type funParamKind =
   | Parameter of {
       attrs: Parsetree.attributes;

tests/parsing/errors/other/expected/spread.res.txt

@@ -100,7 +100,7 @@ let arr = [|x;y|]
 let [|arr;_|] = [|1;2;3|]
 let record = { x with y }
 let { x; y } = myRecord
-let myList = Belt.List.concatMany [|x;y|]
+let myList = x @ y
 let x::y = myList
 type nonrec t = < a  > 
 type nonrec t =

tests/parsing/grammar/expressions/expected/list.res.txt

@@ -3,5 +3,5 @@ let x = [1; 2; 3]
 let x = [1; 2; 3]
 let x = [(1 : int); (2 : int); (3 : int)]
 let x = 4 :: 5 :: y
-let x = Belt.List.concatMany [|(1 :: x);(2 :: 3 :: x)|]
+let x = (1 :: x) @ (2 :: 3 :: x)
 let x = 1 :: 2 :: (y : int list)

tests/printer/expr/expected/list.res.txt

@@ -2,7 +2,7 @@ let x = list{}
 let x = list{1}
 let x = list{1, 2}
 let x = list{1, 2, 3}
-let x = Belt.List.concatMany([list{1, 2, ...x}, list{3, ...x}])
+let x = list{1, 2, ...x3, ...x}
 
 let x = list{
   superLoooooooooooooooooooooooooooooongIiiiiiiiiideeeentifieeeeeeeeeeeeeeeeer,
@@ -19,14 +19,10 @@ let x = list{
   ...superLoooooooooooooooooooooooooooooongListHere,
 }
 
-let x = Belt.List.concatMany([
-  list{
-    superLoooooooooooooooooooooooooooooongIiiiiiiiiideeeentifieeeeeeeeeeeeeeeeer,
-    superLoooooooooooooooooooooooooooooongIiiiiiiiiideeeentifieeeeeeeeeeeeeeeeer,
-    ...superLoooooooooooooooooooooooooooooongListHere,
-  },
-  list{
-    superLoooooooooooooooooooooooooooooongIiiiiiiiiideeeentifieeeeeeeeeeeeeeeeer,
-    ...superLoooooooooooooooooooooooooooooongListHere,
-  },
-])
+let x = list{
+  superLoooooooooooooooooooooooooooooongIiiiiiiiiideeeentifieeeeeeeeeeeeeeeeer,
+  superLoooooooooooooooooooooooooooooongIiiiiiiiiideeeentifieeeeeeeeeeeeeeeeer,
+  ...superLoooooooooooooooooooooooooooooongListHere
+  superLoooooooooooooooooooooooooooooongIiiiiiiiiideeeentifieeeeeeeeeeeeeeeeer,
+  ...superLoooooooooooooooooooooooooooooongListHere,
+}