git.iko.soy/patch
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patch/src/Data/Patch.hs
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1{-# LANGUAGE CPP #-}
2{-# LANGUAGE GeneralizedNewtypeDeriving #-}
3{-# LANGUAGE StandaloneDeriving #-}
4{-# LANGUAGE TypeFamilies #-}
5{-# LANGUAGE TypeOperators #-}
6-- |
7-- Module:
8-- Data.Patch
9-- Description:
10-- This module defines the 'Patch' class.
11module Data.Patch
12 ( module Data.Patch
13 , module X
14 ) where
16import Control.Applicative
17import Data.Functor.Const (Const (..))
18import Data.Functor.Identity
19import Data.Map.Monoidal (MonoidalMap)
20import Data.Proxy
21#if !MIN_VERSION_base(4,11,0)
22import Data.Semigroup (Semigroup (..))
23#endif
24import GHC.Generics
26import Data.Patch.Class as X
27import Data.Patch.DMap as X hiding (getDeletions)
28import Data.Patch.DMapWithMove as X
29 ( PatchDMapWithMove, const2PatchDMapWithMoveWith, mapPatchDMapWithMove
30 , patchDMapWithMoveToPatchMapWithMoveWith
31 , traversePatchDMapWithMoveWithKey, unPatchDMapWithMove
32 , unsafePatchDMapWithMove, weakenPatchDMapWithMoveWith
33 )
34import Data.Patch.IntMap as X hiding (getDeletions)
35import Data.Patch.Map as X
36import Data.Patch.MapWithMove as X
37 ( PatchMapWithMove, patchMapWithMoveNewElements
38 , patchMapWithMoveNewElementsMap, unPatchMapWithMove
39 , unsafePatchMapWithMove
40 )
42-- | A 'Group' is a 'Monoid' where every element has an inverse.
43class (Semigroup q, Monoid q) => Group q where
44 negateG :: q -> q
45 (~~) :: q -> q -> q
46 r ~~ s = r <> negateG s
48-- | An 'Additive' 'Semigroup' is one where (<>) is commutative
49class Semigroup q => Additive q where
51-- | The elements of an 'Additive' 'Semigroup' can be considered as patches of their own type.
52newtype AdditivePatch p = AdditivePatch { unAdditivePatch :: p }
54instance Additive p => Patch (AdditivePatch p) where
55 type PatchTarget (AdditivePatch p) = p
56 apply (AdditivePatch p) q = Just $ p <> q
58instance (Ord k, Group q) => Group (MonoidalMap k q) where
59 negateG = fmap negateG
61instance (Ord k, Additive q) => Additive (MonoidalMap k q)
63-- | Trivial group.
64instance Group () where
65 negateG _ = ()
66 _ ~~ _ = ()
67instance Additive ()
69-- | Product group. A Pair of groups gives rise to a group
70instance (Group a, Group b) => Group (a, b) where
71 negateG (a, b) = (negateG a, negateG b)
72 (a, b) ~~ (c, d) = (a ~~ c, b ~~ d)
73instance (Additive a, Additive b) => Additive (a, b)
75-- See https://gitlab.haskell.org/ghc/ghc/issues/11135#note_111802 for the reason Compose is not also provided.
76-- Base does not define Monoid (Compose f g a) so this is the best we can
77-- really do for functor composition.
78instance Group (f (g a)) => Group ((f :.: g) a) where
79 negateG (Comp1 xs) = Comp1 (negateG xs)
80 Comp1 xs ~~ Comp1 ys = Comp1 (xs ~~ ys)
81instance Additive (f (g a)) => Additive ((f :.: g) a)
83-- | Product of groups, Functor style.
84instance (Group (f a), Group (g a)) => Group ((f :*: g) a) where
85 negateG (a :*: b) = negateG a :*: negateG b
86 (a :*: b) ~~ (c :*: d) = (a ~~ c) :*: (b ~~ d)
87instance (Additive (f a), Additive (g a)) => Additive ((f :*: g) a)
89-- | Trivial group, Functor style
90instance Group (Proxy x) where
91 negateG _ = Proxy
92 _ ~~ _ = Proxy
93instance Additive (Proxy x)
95-- | Const lifts groups into a functor.
96deriving instance Group a => Group (Const a x)
97instance Additive a => Additive (Const a x)
98-- | Identity lifts groups pointwise (at only one point)
99deriving instance Group a => Group (Identity a)
100instance Additive a => Additive (Identity a)
102-- | Functions lift groups pointwise.
103instance Group b => Group (a -> b) where
104 negateG f = negateG . f
105 (~~) = liftA2 (~~)
106instance Additive b => Additive (a -> b)