Avoid adding redundant points to ring buffer.

1 files changed, 6 insertions, 0 deletions

diff --git a/SmallRing.hs b/SmallRing.hs
index d792899..f710393 100644
--- a/SmallRing.hs
+++ b/SmallRing.hs
@@ -30,6 +30,12 @@ pushFront a (Give1 f) = Give2 (\g -> f (g a))
 pushFront a (Give2 f) = Give3 (\g -> f (g a))
 pushFront a (Give3 f) = f $ \b c _ -> Give3 $ \g -> g a b c
 
+front :: Giver a -> Maybe a
+front Give0     = Nothing
+front (Give1 f) = f Just
+front (Give2 g) = g (\x _ -> Just x)
+front (Give3 h) = h (\x _ _ -> Just x)
+
 take3 :: (a -> a -> a -> b) -> Giver a -> Maybe b
 take3 f (Give3 g) = Just (g f)
 take3 _ _         = Nothing