Fix lazy-storing behaviour of Pair

1 files changed, 8 insertions, 4 deletions

diff --git a/SC/Exp.hs b/SC/Exp.hs
index 5ddd4bf..5c0bc72 100644
--- a/SC/Exp.hs
+++ b/SC/Exp.hs
@@ -91,10 +91,14 @@ compileExp' aenv env = \case
     A.Pair a b -> do
         (usedA1, res1) <- compileExp' aenv env a
         (usedA2, res2) <- compileExp' aenv env b
-        return (usedA1 ++ usedA2, Left (\case
-            ITupPair n1 n2 -> toStoring res1 n1 ++ toStoring res2 n2
-            ITupIgnore -> []
-            ITupSingle _ -> error "wat"))
+        return (usedA1 ++ usedA2
+               ,case (res1, res2) of
+                  (Right (sts1, exp1), Right (sts2, exp2)) ->
+                      Right (sts1 ++ sts2, ITupPair exp1 exp2)
+                  _ -> Left (\case
+                                ITupPair n1 n2 -> toStoring res1 n1 ++ toStoring res2 n2
+                                ITupIgnore -> []
+                                ITupSingle _ -> error "wat"))
 
     A.Const ty x
       | Just str <- showExpConst ty x