scope and comparison

src/exec.ml

@@ -2,23 +2,31 @@ open Types
 
 let update m x v = fun y -> if x=y then v else m y
 
-let rec builtin_iop f =
-  let iop1 m v =
-    match m "", v with
-    | VInt a, VInt b -> EInt (f a b)
-    | _, _ -> raise (Failure "iop: not int") in
-  VFn (builtin, "", EFnB iop1)
+let rec _builtin_iop: 'a. ('a->exp) -> (int->int->'a) -> value =
+  fun ret f ->
+    let iop1 m v =
+      match m "", v with
+      | VInt a, VInt b -> ret (f a b)
+      | _, _ -> raise (Failure "not int") in
+    VFn (builtin, "", EFnB iop1)
+and builtin_iop x = _builtin_iop (fun x -> EInt x) x
+and builtin_cop a = _builtin_iop (fun x -> EBool x) a
 and builtin_bop f =
   let bop1 m v =
     match m "", v with
     | VBool a, VBool b -> EBool (f a b)
-    | _, _ -> raise (Failure "bop: not bool") in
+    | _, _ -> raise (Failure "not bool") in
   VFn (builtin, "", EFnB bop1)
 and builtin = function
   | "add" -> builtin_iop (+)
   | "sub" -> builtin_iop (-)
   | "mul" -> builtin_iop ( * )
   | "div" -> builtin_iop (/)
+  | "lt" -> builtin_cop (<)
+  | "gt" -> builtin_cop (>)
+  | "ge" -> builtin_cop (>=)
+  | "le" -> builtin_cop (<=)
+  | "eq" -> builtin_cop (=)
   | "and" -> builtin_bop (&&)
   | "or" -> builtin_bop (||)
   | _ -> raise (Failure "undefined var")

src/lexer.mll

@@ -6,14 +6,19 @@ rule token = parse
     { token lexbuf }
   | '(' { LPAREN }
   | ')' { RPAREN }
-  (* | '{' { LBRACE } *)
-  (* | '}' { RBRACE } *)
+  | '{' { LBRACE }
+  | '}' { RBRACE }
   | ';' { SEMICOLON }
   | '=' { EQUAL }
   | '+' { PLUS }
   | '-' { MINUS }
   | '*' { TIMES }
   | '/' { DIVIDE }
+  | '<' { LT }
+  | '>' { GT }
+  | "<=" { LE }
+  | ">=" { GE }
+  | "==" { EQ }
   | "&&" { AND }
   | "||" { OR }
   | "if" { IF }

src/parser.mly

@@ -2,8 +2,8 @@
   open Types
   let app2 x a b = EApp (EApp (EVar x, a), b)
 %}
-%token LPAREN RPAREN SEMICOLON EQUAL OR AND PLUS MINUS TIMES DIVIDE EOF
-%token IF THEN ELSE TRUE FALSE FN
+%token LPAREN RPAREN LBRACE RBRACE SEMICOLON EQUAL OR AND PLUS MINUS TIMES DIVIDE EOF
+%token IF THEN ELSE TRUE FALSE FN LT GT LE GE EQ
 %token<int> NUM
 %token<string> VAR
 
@@ -14,6 +14,7 @@
 %nonassoc TRUE FALSE
 %left PLUS MINUS
 %left TIMES DIVIDE
+%nonassoc LT GT LE GE EQ
 %nonassoc NUM VAR
 %right LPAREN RPAREN
 %nonassoc EOF
@@ -48,8 +49,19 @@ parse_exp:
       { app2 "mul" $1 $3 }
   | parse_exp DIVIDE parse_exp
       { app2 "div" $1 $3 }
+  | parse_exp LT parse_exp
+      { app2 "lt" $1 $3 }
+  | parse_exp GT parse_exp
+      { app2 "gt" $1 $3 }
+  | parse_exp LE parse_exp
+      { app2 "le" $1 $3 }
+  | parse_exp GE parse_exp
+      { app2 "ge" $1 $3 }
+  | parse_exp EQ parse_exp
+      { app2 "eq" $1 $3 }
   | FN VAR parse_exp
       { EFn ($2,$3) }
+  | LBRACE parse_stmt RBRACE { EScope $2 }
 
 exp:
   | NUM { EInt $1 }