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{-# 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
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