make assign expression

Author: adamrk

lib/ast.ml

@@ -21,9 +21,10 @@ type token =
   (* unknown *)
   | KWD of char
   (* special chars *)
+  | EQUALS
+  | ASSIGN
   | LEFT_PAREN
   | RIGHT_PAREN
-  | EQUALS
   | COMMA
   | SEMICOLON
   (* end of file *)

lib/ast.mli

@@ -1,24 +1,33 @@
 open Core
 
 type token =
+  (* commands *)
   | DEF
   | EXTERN
+  (* control *)
   | IF
   | THEN
   | ELSE
   | FOR
   | IN
+  (* operators *)
   | BINARY
   | UNARY
+  (* var definition *)
   | VAR
+  (* primary *)
   | IDENT of string
   | NUMBER of float
+  (* unknown *)
   | KWD of char
+  (* special chars *)
+  | EQUALS
+  | ASSIGN
   | LEFT_PAREN
   | RIGHT_PAREN
-  | EQUALS
   | COMMA
   | SEMICOLON
+  (* end of file *)
   | EOF
 [@@deriving sexp]
 

lib/lexer.mll

@@ -16,25 +16,25 @@
     | newline  { read lexbuf }
     | "def"    { DEF }
     | "extern" { EXTERN }
-    | "if"     { IF  }
-    | "then"   { THEN  }
-    | "else"   { ELSE  }
-    | "for"    { FOR  }
-    | "in"     { IN  }
-    | "binary" { BINARY  }
-    | "unary"  { UNARY  }
-    | "var"    { VAR  }
-    | id       { IDENT (Lexing.lexeme lexbuf)  }
-    | float    { NUMBER (float_of_string (Lexing.lexeme lexbuf))  }
-    | "="      { EQUALS  }
-    | "("      { LEFT_PAREN  }
-    | ")"      { RIGHT_PAREN  }
-    | ","      { COMMA  }
-    | ";"      { SEMICOLON  }
+    | "if"     { IF }
+    | "then"   { THEN }
+    | "else"   { ELSE }
+    | "for"    { FOR }
+    | "in"     { IN }
+    | "binary" { BINARY }
+    | "unary"  { UNARY }
+    | "var"    { VAR }
+    | id       { IDENT (Lexing.lexeme lexbuf) }
+    | float    { NUMBER (float_of_string (Lexing.lexeme lexbuf)) }
+    | ":="     { ASSIGN }
+    | "("      { LEFT_PAREN }
+    | ")"      { RIGHT_PAREN }
+    | ","      { COMMA }
+    | ";"      { SEMICOLON }
     (* '#' marks the beginning of a comment *)
     | "#"      { read_comment lexbuf }
-    | _        { KWD (Lexing.lexeme_char lexbuf 0)  }
-    | eof      { EOF  }
+    | _        { KWD (Lexing.lexeme_char lexbuf 0) }
+    | eof      { EOF }
 
   and read_comment =
     parse

lib/parser.mly

@@ -12,6 +12,7 @@
 %token <float> NUMBER
 %token <char> KWD
 %token EQUALS
+%token ASSIGN
 %token LEFT_PAREN
 %token RIGHT_PAREN
 %token COMMA
@@ -28,7 +29,7 @@
     | Some p -> p
 %}
 
-%start < [`Expr of Ast.Expr.No_binop.func 
+%start < [ `Expr of Ast.Expr.No_binop.func 
          | `Extern of Ast.proto 
          | `Def of Ast.Expr.No_binop.func 
          | `Eof ]> toplevel
@@ -75,7 +76,7 @@ block:
 
   (* var
    *   ::= 'var' identifier ('=' expression)? *)
-var: name = IDENT; e = option(EQUALS; e = expr { e }) { (name, e) }
+var: name = IDENT; e = option(ASSIGN; e = expr { e }) { (name, e) }
 
   (* unary
    *   ::= primary