vm: got the VM to finally actually work

lib/vm/native.ml

@@ -3,17 +3,24 @@
    Stuff like printing to the screen, file I/O etc will be implemented
    here.
  *)
-
 open Types
-
-let builtin_print (v : value) =
-  ignore v;
-  Nil
+let builtin_print (v : Types.value) =
+  let p = Printf.sprintf in
+  let rec aux_print = function
+    | Int x -> p "%d" x
+    | Double x -> p "%f" x
+    | String x -> p "\"%s\"" x
+    | Nil -> p "'()"
+    | Cons (a, b) -> p "(%s . %s)" (aux_print a) (aux_print b)
+    | Symbol x -> p "'%s" x
+    | Closure (i, _) -> p "<closure %d>" i
+    | Native i -> p "<native %d>" i in
+  print_endline (aux_print v);
+  Types.Nil
 
 let table = [|
     builtin_print
   |]
 
 
-