string concat

README.md

@@ -65,7 +65,7 @@ dune runtest
     - [ ] > , =>
     - [ ] <, =<
   - [ ] String ops
-    - [ ] ^ (string concat)
+    - [x] ++ (string concat)
     - [ ] ==
     - [ ] !=
     - [ ] > , =>

src/ast/parsed.ml

@@ -1,6 +1,6 @@
 open Common
 
-type op = Add | Subt | Mult | Div | Mod | Eq
+type op = Add | Subt | Mult | Div | Mod | Concat | Eq
 type vals = Unit | Int of int | Char of char | String of string | Bool of bool
 
 type t =

src/evaluating/eval.ml

@@ -57,6 +57,7 @@ and eval_bop ctx op e1 e2 =
   | Mult, VInt a, VInt b -> (VInt (a * b), ctx)
   | 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)
   | Eq, VInt a, VInt b -> (VBool (a = b), ctx)
   | _ -> op_error ()
 

src/parsing/lexer.mll

@@ -17,15 +17,17 @@ let newl = '\n'
 let digit = ['0'-'9']
 let int = '-'? digit+
 let letter = ['_' 'a'-'z' 'A'-'Z'] ['a'-'z' 'A'-'Z' '_' '0'-'9']*
+let letter_space = ['_' 'a'-'z' ' ' 'A'-'Z'] ['a'-'z' 'A'-'Z' ' ' '_' '0'-'9']*
 let char = '\'' ['a'-'z'] '\''
-let str = '\"' letter+ '\"'
+let str = '\"' letter_space+ '\"'
 let ident = letter+
 
 rule read =
   parse
   | white { read lexbuf }
   | newl { new_line read lexbuf }
   | ";" { SEMICOLON }
+  | "++" { PLUSPLUS }
   | "+" { PLUS }
   | "-" { MINUS }
   | "*" { MULT }

src/parsing/parser.mly

@@ -31,6 +31,7 @@
 %token DOTDOT
 %token BAR
 
+%token PLUSPLUS
 %token PLUS
 %token MINUS
 %token MULT
@@ -96,6 +97,7 @@ expr:
 
 bop:
   | PLUS { Add }
+  | PLUSPLUS { Concat }
   | MINUS { Subt }
   | MULT { Mult }
   | DIV { Div }

src/typing/typecheck.ml

@@ -79,12 +79,13 @@ and typeof_bop ctx op e1 e2 pos =
   | (Div as op), t1, t2
   | (Mod as op), t1, t2 ->
       typeof_bop_int ctx op t1 t2 pos
+  | Concat, t1, t2 -> unify_bop ctx t1 t2 TString TString pos
   | Eq, t1, t2 -> unify_bop ctx t1 t2 TInt TBool pos
 
 and typeof_bop_int ctx op t1 t2 pos =
   match op with
   | Add | Subt | Mult | Div | Mod -> unify_bop ctx t1 t2 TInt TInt pos
-  | Eq -> assert false
+  | Concat | Eq -> assert false
 
 and typeof_let ctx name binding in_body =
   enter_level ();

test/parsing_test/parsing_test.ml

@@ -72,11 +72,11 @@ let%test "char variable" =
   | _ -> false
 
 let%test "string variable" =
-  match test "let a = \"testing\"" with
+  match test "let a = \"testing stuff\"" with
   | Let
       {
         name = "a";
-        binding = { expr = Const (String "testing"); _ };
+        binding = { expr = Const (String "testing stuff"); _ };
         in_body = None;
       } ->
       true