1 files changed, 11 insertions, 2 deletions
diff --git a/Graphics/Glyph/BufferBuilder.hs b/Graphics/Glyph/BufferBuilder.hs
index 9dae0aa..b23f6ba 100644
--- a/Graphics/Glyph/BufferBuilder.hs
+++ b/Graphics/Glyph/BufferBuilder.hs
@@ -104,7 +104,17 @@ instance Show (CompiledBuild x) where
     show (CompiledBuild stride enabled n ptr nbytes) =
         "[CompiledBuild stride="++!stride++" enabled"++!enabled++" n="++!n++" ptr="++!ptr++" nbytes="++!nbytes++"]"
 
-instance (Num t) => Monad (BuilderM t) where
+instance Functor (BuilderM t) where
+  fmap f b = b >>= (return . f)
+
+instance Applicative (BuilderM t) where
+  pure = return
+  (<*>) afn aa = do
+    fn <- afn
+    a <- aa
+    return (fn a)
+
+instance Monad (BuilderM t) where
     (BuilderM !builder1 _) >> (BuilderM !builder2 ret) =
         BuilderM (builder1 ><> builder2) ret
         where
@@ -118,7 +128,6 @@ instance (Num t) => Monad (BuilderM t) where
     b1@(BuilderM _ ret) >>= func = b1 >> func ret
 
     return = BuilderM (LeafBuilder Seq.empty)
-    fail = undefined
 
 instance Functor Builder where
     fmap f (Builder b1 b2) = (Builder (fmap f b1) (fmap f b2))