Merge pull request #125 from phadej/map-coerce

Use coerce to implement mapII and co

Author: kosmikus

sop-core/src/Data/SOP/BasicFunctors.hs

@@ -56,6 +56,8 @@ import Control.DeepSeq (NFData(..))
 import Control.DeepSeq (NFData1(..), NFData2(..))
 #endif
 
+import Data.Coerce (coerce)
+
 -- * Basic functors
 
 -- | The constant type functor.
@@ -274,105 +276,98 @@ unComp (Comp x) = x
 
 -- * Mapping functions
 
--- Implementation note:
---
--- All of these functions are just type specializations of
--- 'coerce'. However, we currently still support GHC 7.6
--- which does not support 'coerce', so we write them
--- explicitly.
-
 -- | Lift the given function.
 --
 -- @since 0.2.5.0
 --
 mapII :: (a -> b) -> I a -> I b
-mapII = \ f (I a) -> I (f a)
+mapII = coerce
 {-# INLINE mapII #-}
 
 -- | Lift the given function.
 --
 -- @since 0.2.5.0
 --
 mapIK :: (a -> b) -> I a -> K b c
-mapIK = \ f (I a) -> K (f a)
+mapIK = coerce
 {-# INLINE mapIK #-}
 
 -- | Lift the given function.
 --
 -- @since 0.2.5.0
 --
 mapKI :: (a -> b) -> K a c -> I b
-mapKI = \ f (K a) -> I (f a)
+mapKI = coerce
 {-# INLINE mapKI #-}
 
 -- | Lift the given function.
 --
 -- @since 0.2.5.0
 --
 mapKK :: (a -> b) -> K a c -> K b d
-mapKK = \ f (K a) -> K (f a)
+mapKK = coerce
 {-# INLINE mapKK #-}
 
 -- | Lift the given function.
 --
 -- @since 0.2.5.0
 --
 mapIII :: (a -> b -> c) -> I a -> I b -> I c
-mapIII = \ f (I a) (I b) -> I (f a b)
+mapIII = coerce
 {-# INLINE mapIII #-}
 
 -- | Lift the given function.
 --
 -- @since 0.2.5.0
 --
 mapIIK :: (a -> b -> c) -> I a -> I b -> K c d
-mapIIK = \ f (I a) (I b) -> K (f a b)
+mapIIK = coerce
 {-# INLINE mapIIK #-}
 
 -- | Lift the given function.
 --
 -- @since 0.2.5.0
 --
 mapIKI :: (a -> b -> c) -> I a -> K b d -> I c
-mapIKI = \ f (I a) (K b) -> I (f a b)
+mapIKI = coerce
 {-# INLINE mapIKI #-}
 
 -- | Lift the given function.
 --
 -- @since 0.2.5.0
 --
 mapIKK :: (a -> b -> c) -> I a -> K b d -> K c e
-mapIKK = \ f (I a) (K b) -> K (f a b)
+mapIKK = coerce
 {-# INLINE mapIKK #-}
 
 -- | Lift the given function.
 --
 -- @since 0.2.5.0
 --
 mapKII :: (a -> b -> c) -> K a d -> I b -> I c
-mapKII = \ f (K a) (I b) -> I (f a b)
+mapKII = coerce
 {-# INLINE mapKII #-}
 
 -- | Lift the given function.
 --
 -- @since 0.2.5.0
 --
 mapKIK :: (a -> b -> c) -> K a d -> I b -> K c e
-mapKIK = \ f (K a) (I b) -> K (f a b)
+mapKIK = coerce
 {-# INLINE mapKIK #-}
 
 -- | Lift the given function.
 --
 -- @since 0.2.5.0
 --
 mapKKI :: (a -> b -> c) -> K a d -> K b e -> I c
-mapKKI = \ f (K a) (K b) -> I (f a b)
+mapKKI = coerce
 {-# INLINE mapKKI #-}
 
 -- | Lift the given function.
 --
 -- @since 0.2.5.0
 --
 mapKKK :: (a -> b -> c) -> K a d -> K b e -> K c f
-mapKKK = \ f (K a) (K b) -> K (f a b)
+mapKKK = coerce
 {-# INLINE mapKKK #-}