1 files changed, 10 insertions, 1 deletions
diff --git a/Graphics/Glyph/Util.hs b/Graphics/Glyph/Util.hs
index 2a3e060..90640a4 100644
--- a/Graphics/Glyph/Util.hs
+++ b/Graphics/Glyph/Util.hs
@@ -286,11 +286,20 @@ plusM a = MonadPlusBuilder a ()
 runMonadPlusBuilder :: MonadPlusBuilder a b -> a
 runMonadPlusBuilder (MonadPlusBuilder !a _) = a
 
+instance (MonadPlus a) => Functor (MonadPlusBuilder (a b)) where
+  fmap f b = b >>= return . f  
+
+instance (MonadPlus a) => Applicative (MonadPlusBuilder (a b)) where
+  (<*>) afn aa = do
+    fn <- afn
+    fn <$> aa
+
+  pure = return
+
 instance (MonadPlus a) => Monad (MonadPlusBuilder (a b)) where
     return = MonadPlusBuilder mzero
     MonadPlusBuilder a1 _ >> MonadPlusBuilder a2 b = MonadPlusBuilder (a1 `mplus` a2) b
     builder@(MonadPlusBuilder _ b) >>= f = builder >> f b
-    fail = undefined
 
 untilM2 :: (Monad m) => (a -> m Bool) -> a -> (a -> m a) -> m a
 untilM2 cond ini bod = do