1{-# LANGUAGE CPP #-}
2{-# LANGUAGE DeriveDataTypeable #-}
3{-# LANGUAGE FlexibleContexts #-}
4{-# LANGUAGE StandaloneDeriving #-}
5{-# LANGUAGE UndecidableInstances #-}
6
7#if __GLASGOW_HASKELL__ >= 702
8{-# LANGUAGE DeriveGeneric #-}
9#endif
10
11#if __GLASGOW_HASKELL__ >= 704
12{-# LANGUAGE Safe #-}
13#elif __GLASGOW_HASKELL__ >= 702
14{-# LANGUAGE Trustworthy #-}
15#endif
16
17#if __GLASGOW_HASKELL__ >= 706
18{-# LANGUAGE PolyKinds #-}
19#endif
20#include "bifunctors-common.h"
21
22-----------------------------------------------------------------------------
23-- |
24-- Copyright   :  (C) 2008-2016 Edward Kmett
25-- License     :  BSD-style (see the file LICENSE)
26--
27-- Maintainer  :  Edward Kmett <ekmett@gmail.com>
28-- Stability   :  provisional
29-- Portability :  non-portable
30--
31----------------------------------------------------------------------------
32module Data.Bifunctor.Join
33  ( Join(..)
34  ) where
35
36#if __GLASGOW_HASKELL__ < 710
37import Control.Applicative
38#endif
39
40import Data.Biapplicative
41import Data.Bifoldable
42import Data.Bitraversable
43
44#if __GLASGOW_HASKELL__ < 710
45import Data.Foldable
46import Data.Traversable
47#endif
48
49#if __GLASGOW_HASKELL__ >= 708
50import Data.Typeable
51#endif
52
53#if __GLASGOW_HASKELL__ >= 702
54import GHC.Generics
55#endif
56
57#if LIFTED_FUNCTOR_CLASSES
58import Data.Functor.Classes
59#endif
60
61-- | Make a 'Functor' over both arguments of a 'Bifunctor'.
62newtype Join p a = Join { runJoin :: p a a }
63  deriving
64    (
65#if __GLASGOW_HASKELL__ >= 702
66      Generic
67#endif
68#if __GLASGOW_HASKELL__ >= 708
69    , Typeable
70#endif
71    )
72
73deriving instance Eq   (p a a) => Eq   (Join p a)
74deriving instance Ord  (p a a) => Ord  (Join p a)
75deriving instance Show (p a a) => Show (Join p a)
76deriving instance Read (p a a) => Read (Join p a)
77
78#if LIFTED_FUNCTOR_CLASSES
79instance Eq2 p => Eq1 (Join p) where
80  liftEq f (Join x) (Join y) = liftEq2 f f x y
81
82instance Ord2 p => Ord1 (Join p) where
83  liftCompare f (Join x) (Join y) = liftCompare2 f f x y
84
85instance Read2 p => Read1 (Join p) where
86  liftReadsPrec rp1 rl1 p = readParen (p > 10) $ \s0 -> do
87    ("Join",    s1) <- lex s0
88    ("{",       s2) <- lex s1
89    ("runJoin", s3) <- lex s2
90    (x,         s4) <- liftReadsPrec2 rp1 rl1 rp1 rl1 0 s3
91    ("}",       s5) <- lex s4
92    return (Join x, s5)
93
94instance Show2 p => Show1 (Join p) where
95  liftShowsPrec sp1 sl1 p (Join x) = showParen (p > 10) $
96      showString "Join {runJoin = "
97    . liftShowsPrec2 sp1 sl1 sp1 sl1 0 x
98    . showChar '}'
99#endif
100
101instance Bifunctor p => Functor (Join p) where
102  fmap f (Join a) = Join (bimap f f a)
103  {-# INLINE fmap #-}
104
105instance Biapplicative p => Applicative (Join p) where
106  pure a = Join (bipure a a)
107  {-# INLINE pure #-}
108  Join f <*> Join a = Join (f <<*>> a)
109  {-# INLINE (<*>) #-}
110  Join a *> Join b = Join (a *>> b)
111  {-# INLINE (*>) #-}
112  Join a <* Join b = Join (a <<* b)
113  {-# INLINE (<*) #-}
114
115instance Bifoldable p => Foldable (Join p) where
116  foldMap f (Join a) = bifoldMap f f a
117  {-# INLINE foldMap #-}
118
119instance Bitraversable p => Traversable (Join p) where
120  traverse f (Join a) = fmap Join (bitraverse f f a)
121  {-# INLINE traverse #-}
122  sequenceA (Join a) = fmap Join (bisequenceA a)
123  {-# INLINE sequenceA #-}
124