'null?' builtin

2 files changed, 2 insertions, 2 deletions

diff --git a/Compiler.hs b/Compiler.hs
index a5a1f3d..913d568 100644
--- a/Compiler.hs
+++ b/Compiler.hs
@@ -83,7 +83,7 @@ newtype CM a = CM {unCM :: StateT CompState (Except String) a}
 builtinMap :: Map.Map Name ()
 builtinMap = Map.fromList [
     ("+", ()), ("-", ()), ("<=", ()), ("=", ()), ("print", ()),
-    ("list", ()), ("car", ()), ("cdr", ()),
+    ("list", ()), ("car", ()), ("cdr", ()), ("null?", ()),
     ("sys-open-file", ()), ("sys-close-file", ()), ("sys-get-char", ()), ("sys-put-string", ())]
 
 bbId :: BB -> Int
diff --git a/VM.hs b/VM.hs
index 7baea0d..a272829 100644
--- a/VM.hs
+++ b/VM.hs
@@ -112,7 +112,7 @@ vmRunBuiltin state "=" [a, b] = return (if equalOp a b then RVNum 1 else RVNum 0
 vmRunBuiltin state "<=" [RVNum a, RVNum b] = return (RVNum (fromEnum (a <= b)), state)
 vmRunBuiltin state "+" [RVNum a, RVNum b] = return (RVNum (a + b), state)
 vmRunBuiltin state "-" [RVNum a, RVNum b] = return (RVNum (a - b), state)
--- TODO: null?
+vmRunBuiltin state "null?" [v] = return (RVNum (case v of { RVList [] -> 1; _ -> 0 }), state)
 vmRunBuiltin state "car" [RVList l] = case l of
     a : _ -> return (a, state)
     _ -> throw "Empty list in 'car'"