add list syntactic sugar, eg: (1 2) instead of (1 . (2 . ()))

1 files changed, 10 insertions, 3 deletions

diff --git a/lisp.y b/lisp.y
index c2ca8f5..a15b451 100644
--- a/lisp.y
+++ b/lisp.y
@@ -23,7 +23,7 @@ static int is_integer(double x) {
 %token <ival> LPAREN RPAREN DOT WHITESPACE
 %token <ival> PLUS MINUS MULT DIV
 
-%type <val> sexpr atom
+%type <val> sexpr atom list list_items
 
 %start sexprs
 
@@ -32,9 +32,10 @@ opt_ws: /* matches no whitespace */
       | WHITESPACE;
 
 sexprs: sexpr { print_val($1); printf("\n"); }
-      | sexprs opt_ws sexpr { print_val($3); };
+      | sexprs opt_ws sexpr { print_val($3); printf("\n"); };
 
 sexpr:  atom
+     |  list
      |  LPAREN opt_ws sexpr opt_ws DOT opt_ws sexpr opt_ws RPAREN
      {
        $$ = cons($3, $7);
@@ -42,6 +43,13 @@ sexpr:  atom
        printf("\n");
      };
 
+list: LPAREN opt_ws list_items opt_ws RPAREN
+    { $$ = $3; };
+
+list_items: /* empty list */ { $$ = make_nil(); }
+          | sexpr opt_ws list_items { $$ = cons($1, $3); }
+          | sexpr WHITESPACE DOT WHITESPACE sexpr { $$ = cons($1, $5); };
+
 atom:   NUMBER
     {
       if(is_integer($1)) {
@@ -50,7 +58,6 @@ atom:   NUMBER
         $$ = make_double($1);
       }
     }
-    |   LPAREN opt_ws RPAREN { $$ = make_nil(); }
     |   STRING { $$ = make_string($1); };
 %%