multiple issues with list append still unresolved

README.md

@@ -69,7 +69,7 @@ dune runtest
     - [x] ++ (string concat)
     - [ ] I don't know yet
   - [x] 'a list
-    - [x] - (append)
+    - [x] @ (append)
     - [x] :: (cons)
 - [ ] Garbage Collection
 

src/ast/parsed.ml

@@ -6,6 +6,7 @@ type op =
   | Mult
   | Div
   | Mod
+  | LstAppend
   | Cons
   | Concat
   | Eq

src/evaluating/eval.ml

@@ -47,7 +47,7 @@ and eval_bop ctx op e1 e2 =
   | Div, VInt a, VInt b -> (VInt (a / b), ctx)
   | Mod, VInt a, VInt b -> (VInt (a mod b), ctx)
   | Concat, VString a, VString b -> (VString (a ^ b), ctx)
-  | Add, VList a, VList b -> (VList (List.append a b), ctx)
+  | LstAppend, VList a, VList b -> (VList (List.append a b), ctx)
   | Cons, a, VList b -> (VList (a :: b), ctx)
   | Eq, a, b -> (VBool (a = b), ctx)
   | Ineq, a, b -> (VBool (a <> b), ctx)

src/parsing/lexer.mll

@@ -33,6 +33,7 @@ rule read =
   | "*" { MULT }
   | "/" { DIV }
   | "%" { MODULUS }
+  | "@" { AT }
   | "::" { CONS }
   | "=" { EQUALS }
   | "==" { EQ }

src/parsing/parser.mly

@@ -49,6 +49,7 @@
 %token MULT
 %token DIV
 %token MODULUS
+%token AT
 %token CONS
 %token EQ
 %token INEQ
@@ -124,6 +125,7 @@ bop:
   | MULT { Mult }
   | DIV { Div }
   | MODULUS { Mod }
+  | AT { LstAppend }
   | CONS { Cons }
   | EQ { Eq }
   | INEQ { Ineq }

src/typing/typecheck.ml

@@ -91,7 +91,10 @@ and if_branch ctx e2 e3 pos =
 
 and typeof_bop ctx op e1 e2 pos =
   match (op, typeof ctx e1 |> fst |> head, typeof ctx e2 |> fst |> head) with
-  | Add, (TList _ as a), (TList _ as b) -> unify_bop ctx a b (TList a) pos
+  | LstAppend, (TList _ as t1), (TList _ as t2) -> unify_bop ctx t1 t2 t1 pos
+  | LstAppend, t1, (TList _ as t2) -> unify_bop ctx t1 t2 t2 pos
+  | LstAppend, (TList _ as t1), t2 -> unify_bop ctx t1 t2 t1 pos
+  | LstAppend, t1, t2 -> unify_bop ctx t1 t2 (TList (newvar ())) pos
   | Cons, t1, (TList t2 as b) -> unify_bop ctx t1 t2 b pos
   | (Add as op), t1, t2
   | (Subt as op), t1, t2
@@ -112,7 +115,7 @@ and typeof_bop ctx op e1 e2 pos =
 and typeof_bop_int ctx op t1 t2 pos =
   match op with
   | Add | Subt | Mult | Div | Mod -> unify_bop ctx t1 t2 TInt pos
-  | Concat | Cons | Eq | Ineq | Lt | Lte | Bt | Bte -> assert false
+  | Concat | LstAppend | Cons | Eq | Ineq | Lt | Lte | Bt | Bte -> assert false
 
 and typeof_bop_equalities ctx t1 t2 pos =
   match (t1 |> head, t2 |> head) with

test/eval_test/eval_test.ml

@@ -123,14 +123,14 @@ let%test "list tests" =
 
 let%test "list append" =
   match
-    ( test "[1; 2] + [3; 4]" ECtx.empty |> string_of_val,
-      test "[\"str\"; \"str2\"] + [\"str3\"; \"str4\"]" ECtx.empty
+    ( test "[1; 2] @ [3; 4]" ECtx.empty |> string_of_val,
+      test "[\"str\"; \"str2\"] @ [\"str3\"; \"str4\"]" ECtx.empty
       |> string_of_val )
   with
   | "[1; 2; 3; 4]", "[\"str\"; \"str2\"; \"str3\"; \"str4\"]" -> true
   | _ -> false
 
-let%test "list append" =
+let%test "list cons" =
   match
     ( test "1 :: [2; 3]" ECtx.empty |> string_of_val,
       test "\"str\" :: [\"str2\"; \"str3\"]" ECtx.empty |> string_of_val )