1 files changed, 60 insertions, 0 deletions
diff --git a/third_party/bazel/rules_haskell/examples/vector/Data/Vector/Fusion/Util.hs b/third_party/bazel/rules_haskell/examples/vector/Data/Vector/Fusion/Util.hs
new file mode 100644
index 0000000000..855bf5ddd4
--- /dev/null
+++ b/third_party/bazel/rules_haskell/examples/vector/Data/Vector/Fusion/Util.hs
@@ -0,0 +1,60 @@
+{-# LANGUAGE CPP #-}
+-- |
+-- Module      : Data.Vector.Fusion.Util
+-- Copyright   : (c) Roman Leshchinskiy 2009
+-- License     : BSD-style
+--
+-- Maintainer  : Roman Leshchinskiy <rl@cse.unsw.edu.au>
+-- Stability   : experimental
+-- Portability : portable
+--
+-- Fusion-related utility types
+--
+
+module Data.Vector.Fusion.Util (
+  Id(..), Box(..),
+
+  delay_inline, delayed_min
+) where
+
+#if !MIN_VERSION_base(4,8,0)
+import Control.Applicative (Applicative(..))
+#endif
+
+-- | Identity monad
+newtype Id a = Id { unId :: a }
+
+instance Functor Id where
+  fmap f (Id x) = Id (f x)
+
+instance Applicative Id where
+  pure = Id
+  Id f <*> Id x = Id (f x)
+
+instance Monad Id where
+  return = pure
+  Id x >>= f = f x
+
+-- | Box monad
+data Box a = Box { unBox :: a }
+
+instance Functor Box where
+  fmap f (Box x) = Box (f x)
+
+instance Applicative Box where
+  pure = Box
+  Box f <*> Box x = Box (f x)
+
+instance Monad Box where
+  return = pure
+  Box x >>= f = f x
+
+-- | Delay inlining a function until late in the game (simplifier phase 0).
+delay_inline :: (a -> b) -> a -> b
+{-# INLINE [0] delay_inline #-}
+delay_inline f = f
+
+-- | `min` inlined in phase 0
+delayed_min :: Int -> Int -> Int
+{-# INLINE [0] delayed_min #-}
+delayed_min m n = min m n