diff options
Diffstat (limited to 'libraries')
| -rw-r--r-- | libraries/base/Data/Functor/Classes.hs | 79 | ||||
| -rw-r--r-- | libraries/base/Data/Functor/Compose.hs | 35 | ||||
| -rw-r--r-- | libraries/base/Data/Functor/Product.hs | 31 | ||||
| -rw-r--r-- | libraries/base/Data/Functor/Sum.hs | 28 | ||||
| -rw-r--r-- | libraries/base/changelog.md | 5 |
5 files changed, 111 insertions, 67 deletions
diff --git a/libraries/base/Data/Functor/Classes.hs b/libraries/base/Data/Functor/Classes.hs index e547dd12ad..92f3f89e1e 100644 --- a/libraries/base/Data/Functor/Classes.hs +++ b/libraries/base/Data/Functor/Classes.hs @@ -1,7 +1,10 @@ {-# LANGUAGE FlexibleContexts #-} +{-# LANGUAGE DefaultSignatures #-} {-# LANGUAGE InstanceSigs #-} {-# LANGUAGE Safe #-} +{-# LANGUAGE TypeOperators #-} {-# LANGUAGE UndecidableInstances #-} +{-# LANGUAGE QuantifiedConstraints #-} ----------------------------------------------------------------------------- -- | -- Module : Data.Functor.Classes @@ -91,8 +94,18 @@ import Text.Show (showListWith) -- | Lifting of the 'Eq' class to unary type constructors. -- +-- Any instance should be subject to the following law that canonicity +-- is preserved: +-- +-- @liftEq (==)@ = @(==)@ +-- +-- This class therefore represents the generalization of 'Eq' by +-- decomposing its main method into a canonical lifting on a canonical +-- inner method, so that the lifting can be reused for other arguments +-- than the canonical one. +-- -- @since 4.9.0.0 -class Eq1 f where +class (forall a. Eq a => Eq (f a)) => Eq1 f where -- | Lift an equality test through the type constructor. -- -- The function will usually be applied to an equality function, @@ -102,6 +115,10 @@ class Eq1 f where -- -- @since 4.9.0.0 liftEq :: (a -> b -> Bool) -> f a -> f b -> Bool + default liftEq + :: (f ~ f' c, Eq2 f', Eq c) + => (a -> b -> Bool) -> f a -> f b -> Bool + liftEq = liftEq2 (==) -- | Lift the standard @('==')@ function through the type constructor. -- @@ -111,8 +128,18 @@ eq1 = liftEq (==) -- | Lifting of the 'Ord' class to unary type constructors. -- +-- Any instance should be subject to the following law that canonicity +-- is preserved: +-- +-- @liftCompare compare@ = 'compare' +-- +-- This class therefore represents the generalization of 'Ord' by +-- decomposing its main method into a canonical lifting on a canonical +-- inner method, so that the lifting can be reused for other arguments +-- than the canonical one. +-- -- @since 4.9.0.0 -class (Eq1 f) => Ord1 f where +class (Eq1 f, forall a. Ord a => Ord (f a)) => Ord1 f where -- | Lift a 'compare' function through the type constructor. -- -- The function will usually be applied to a comparison function, @@ -122,6 +149,10 @@ class (Eq1 f) => Ord1 f where -- -- @since 4.9.0.0 liftCompare :: (a -> b -> Ordering) -> f a -> f b -> Ordering + default liftCompare + :: (f ~ f' c, Ord2 f', Ord c) + => (a -> b -> Ordering) -> f a -> f b -> Ordering + liftCompare = liftCompare2 compare -- | Lift the standard 'compare' function through the type constructor. -- @@ -131,6 +162,22 @@ compare1 = liftCompare compare -- | Lifting of the 'Read' class to unary type constructors. -- +-- Any instance should be subject to the following laws that canonicity +-- is preserved: +-- +-- @liftReadsPrec readsPrec readList@ = 'readsPrec' +-- +-- @liftReadList readsPrec readList@ = 'readList' +-- +-- @liftReadPrec readPrec readListPrec@ = 'readPrec' +-- +-- @liftReadListPrec readPrec readListPrec@ = 'readListPrec' +-- +-- This class therefore represents the generalization of 'Read' by +-- decomposing it's methods into a canonical lifting on a canonical +-- inner method, so that the lifting can be reused for other arguments +-- than the canonical one. +-- -- Both 'liftReadsPrec' and 'liftReadPrec' exist to match the interface -- provided in the 'Read' type class, but it is recommended to implement -- 'Read1' instances using 'liftReadPrec' as opposed to 'liftReadsPrec', since @@ -145,7 +192,7 @@ compare1 = liftCompare compare -- For more information, refer to the documentation for the 'Read' class. -- -- @since 4.9.0.0 -class Read1 f where +class (forall a. Read a => Read (f a)) => Read1 f where {-# MINIMAL liftReadsPrec | liftReadPrec #-} -- | 'readsPrec' function for an application of the type constructor @@ -219,14 +266,30 @@ liftReadListPrecDefault rp rl = list (liftReadPrec rp rl) -- | Lifting of the 'Show' class to unary type constructors. -- +-- Any instance should be subject to the following laws that canonicity +-- is preserved: +-- +-- @liftShowsPrec showsPrec showList@ = 'showsPrec' +-- +-- @liftShowList showsPrec showList@ = 'showList' +-- +-- This class therefore represents the generalization of 'Show' by +-- decomposing it's methods into a canonical lifting on a canonical +-- inner method, so that the lifting can be reused for other arguments +-- than the canonical one. +-- -- @since 4.9.0.0 -class Show1 f where +class (forall a. Show a => Show (f a)) => Show1 f where -- | 'showsPrec' function for an application of the type constructor -- based on 'showsPrec' and 'showList' functions for the argument type. -- -- @since 4.9.0.0 liftShowsPrec :: (Int -> a -> ShowS) -> ([a] -> ShowS) -> Int -> f a -> ShowS + default liftShowsPrec + :: (f ~ f' b, Show2 f', Show b) + => (Int -> a -> ShowS) -> ([a] -> ShowS) -> Int -> f a -> ShowS + liftShowsPrec = liftShowsPrec2 showsPrec showList -- | 'showList' function for an application of the type constructor -- based on 'showsPrec' and 'showList' functions for the argument type. @@ -248,7 +311,7 @@ showsPrec1 = liftShowsPrec showsPrec showList -- | Lifting of the 'Eq' class to binary type constructors. -- -- @since 4.9.0.0 -class Eq2 f where +class (forall a. Eq a => Eq1 (f a)) => Eq2 f where -- | Lift equality tests through the type constructor. -- -- The function will usually be applied to equality functions, @@ -268,7 +331,7 @@ eq2 = liftEq2 (==) (==) -- | Lifting of the 'Ord' class to binary type constructors. -- -- @since 4.9.0.0 -class (Eq2 f) => Ord2 f where +class (Eq2 f, forall a. Ord a => Ord1 (f a)) => Ord2 f where -- | Lift 'compare' functions through the type constructor. -- -- The function will usually be applied to comparison functions, @@ -302,7 +365,7 @@ compare2 = liftCompare2 compare compare -- For more information, refer to the documentation for the 'Read' class. -- -- @since 4.9.0.0 -class Read2 f where +class (forall a. Read a => Read1 (f a)) => Read2 f where {-# MINIMAL liftReadsPrec2 | liftReadPrec2 #-} -- | 'readsPrec' function for an application of the type constructor @@ -385,7 +448,7 @@ liftReadListPrec2Default rp1 rl1 rp2 rl2 = list (liftReadPrec2 rp1 rl1 rp2 rl2) -- | Lifting of the 'Show' class to binary type constructors. -- -- @since 4.9.0.0 -class Show2 f where +class (forall a. Show a => Show1 (f a)) => Show2 f where -- | 'showsPrec' function for an application of the type constructor -- based on 'showsPrec' and 'showList' functions for the argument types. -- diff --git a/libraries/base/Data/Functor/Compose.hs b/libraries/base/Data/Functor/Compose.hs index 813712f8dd..49955402a6 100644 --- a/libraries/base/Data/Functor/Compose.hs +++ b/libraries/base/Data/Functor/Compose.hs @@ -5,6 +5,7 @@ {-# LANGUAGE PolyKinds #-} {-# LANGUAGE ScopedTypeVariables #-} {-# LANGUAGE Trustworthy #-} +{-# LANGUAGE StandaloneDeriving #-} ----------------------------------------------------------------------------- -- | @@ -32,7 +33,7 @@ import Data.Coerce (coerce) import Data.Data (Data) import Data.Type.Equality (TestEquality(..), (:~:)(..)) import GHC.Generics (Generic, Generic1) -import Text.Read (Read(..), readListDefault, readListPrecDefault) +import Text.Read () infixr 9 `Compose` @@ -47,6 +48,17 @@ newtype Compose f g a = Compose { getCompose :: f (g a) } , Monoid -- ^ @since 4.16.0.0 ) +-- Instances of Prelude classes + +-- | @since 4.18.0.0 +deriving instance Eq (f (g a)) => Eq (Compose f g a) +-- | @since 4.18.0.0 +deriving instance Ord (f (g a)) => Ord (Compose f g a) +-- | @since 4.18.0.0 +deriving instance Read (f (g a)) => Read (Compose f g a) +-- | @since 4.18.0.0 +deriving instance Show (f (g a)) => Show (Compose f g a) + -- Instances of lifted Prelude classes -- | @since 4.9.0.0 @@ -77,27 +89,6 @@ instance (Show1 f, Show1 g) => Show1 (Compose f g) where sp' = liftShowsPrec sp sl sl' = liftShowList sp sl --- Instances of Prelude classes - --- | @since 4.9.0.0 -instance (Eq1 f, Eq1 g, Eq a) => Eq (Compose f g a) where - (==) = eq1 - --- | @since 4.9.0.0 -instance (Ord1 f, Ord1 g, Ord a) => Ord (Compose f g a) where - compare = compare1 - --- | @since 4.9.0.0 -instance (Read1 f, Read1 g, Read a) => Read (Compose f g a) where - readPrec = readPrec1 - - readListPrec = readListPrecDefault - readList = readListDefault - --- | @since 4.9.0.0 -instance (Show1 f, Show1 g, Show a) => Show (Compose f g a) where - showsPrec = showsPrec1 - -- Functor instances -- | @since 4.9.0.0 diff --git a/libraries/base/Data/Functor/Product.hs b/libraries/base/Data/Functor/Product.hs index 114ad6a699..efa6b9977a 100644 --- a/libraries/base/Data/Functor/Product.hs +++ b/libraries/base/Data/Functor/Product.hs @@ -2,6 +2,7 @@ {-# LANGUAGE DeriveGeneric #-} {-# LANGUAGE PolyKinds #-} {-# LANGUAGE Safe #-} +{-# LANGUAGE StandaloneDeriving #-} ----------------------------------------------------------------------------- -- | -- Module : Data.Functor.Product @@ -28,7 +29,7 @@ import Control.Monad.Zip (MonadZip(mzipWith)) import Data.Data (Data) import Data.Functor.Classes import GHC.Generics (Generic, Generic1) -import Text.Read (Read(..), readListDefault, readListPrecDefault) +import Text.Read () -- | Lifted product of functors. data Product f g a = Pair (f a) (g a) @@ -37,6 +38,15 @@ data Product f g a = Pair (f a) (g a) , Generic1 -- ^ @since 4.9.0.0 ) +-- | @since 4.18.0.0 +deriving instance (Eq (f a), Eq (g a)) => Eq (Product f g a) +-- | @since 4.18.0.0 +deriving instance (Ord (f a), Ord (g a)) => Ord (Product f g a) +-- | @since 4.18.0.0 +deriving instance (Read (f a), Read (g a)) => Read (Product f g a) +-- | @since 4.18.0.0 +deriving instance (Show (f a), Show (g a)) => Show (Product f g a) + -- | @since 4.9.0.0 instance (Eq1 f, Eq1 g) => Eq1 (Product f g) where liftEq eq (Pair x1 y1) (Pair x2 y2) = liftEq eq x1 x2 && liftEq eq y1 y2 @@ -60,25 +70,6 @@ instance (Show1 f, Show1 g) => Show1 (Product f g) where showsBinaryWith (liftShowsPrec sp sl) (liftShowsPrec sp sl) "Pair" d x y -- | @since 4.9.0.0 -instance (Eq1 f, Eq1 g, Eq a) => Eq (Product f g a) - where (==) = eq1 - --- | @since 4.9.0.0 -instance (Ord1 f, Ord1 g, Ord a) => Ord (Product f g a) where - compare = compare1 - --- | @since 4.9.0.0 -instance (Read1 f, Read1 g, Read a) => Read (Product f g a) where - readPrec = readPrec1 - - readListPrec = readListPrecDefault - readList = readListDefault - --- | @since 4.9.0.0 -instance (Show1 f, Show1 g, Show a) => Show (Product f g a) where - showsPrec = showsPrec1 - --- | @since 4.9.0.0 instance (Functor f, Functor g) => Functor (Product f g) where fmap f (Pair x y) = Pair (fmap f x) (fmap f y) a <$ (Pair x y) = Pair (a <$ x) (a <$ y) diff --git a/libraries/base/Data/Functor/Sum.hs b/libraries/base/Data/Functor/Sum.hs index affa4e5fc0..2ec25f5588 100644 --- a/libraries/base/Data/Functor/Sum.hs +++ b/libraries/base/Data/Functor/Sum.hs @@ -2,6 +2,7 @@ {-# LANGUAGE DeriveGeneric #-} {-# LANGUAGE PolyKinds #-} {-# LANGUAGE Safe #-} +{-# LANGUAGE StandaloneDeriving #-} ----------------------------------------------------------------------------- -- | -- Module : Data.Functor.Sum @@ -25,7 +26,7 @@ import Control.Applicative ((<|>)) import Data.Data (Data) import Data.Functor.Classes import GHC.Generics (Generic, Generic1) -import Text.Read (Read(..), readListDefault, readListPrecDefault) +import Text.Read () -- | Lifted sum of functors. data Sum f g a = InL (f a) | InR (g a) @@ -34,6 +35,15 @@ data Sum f g a = InL (f a) | InR (g a) , Generic1 -- ^ @since 4.9.0.0 ) +-- | @since 4.18.0.0 +deriving instance (Eq (f a), Eq (g a)) => Eq (Sum f g a) +-- | @since 4.18.0.0 +deriving instance (Ord (f a), Ord (g a)) => Ord (Sum f g a) +-- | @since 4.18.0.0 +deriving instance (Read (f a), Read (g a)) => Read (Sum f g a) +-- | @since 4.18.0.0 +deriving instance (Show (f a), Show (g a)) => Show (Sum f g a) + -- | @since 4.9.0.0 instance (Eq1 f, Eq1 g) => Eq1 (Sum f g) where liftEq eq (InL x1) (InL x2) = liftEq eq x1 x2 @@ -65,22 +75,6 @@ instance (Show1 f, Show1 g) => Show1 (Sum f g) where showsUnaryWith (liftShowsPrec sp sl) "InR" d y -- | @since 4.9.0.0 -instance (Eq1 f, Eq1 g, Eq a) => Eq (Sum f g a) where - (==) = eq1 --- | @since 4.9.0.0 -instance (Ord1 f, Ord1 g, Ord a) => Ord (Sum f g a) where - compare = compare1 --- | @since 4.9.0.0 -instance (Read1 f, Read1 g, Read a) => Read (Sum f g a) where - readPrec = readPrec1 - - readListPrec = readListPrecDefault - readList = readListDefault --- | @since 4.9.0.0 -instance (Show1 f, Show1 g, Show a) => Show (Sum f g a) where - showsPrec = showsPrec1 - --- | @since 4.9.0.0 instance (Functor f, Functor g) => Functor (Sum f g) where fmap f (InL x) = InL (fmap f x) fmap f (InR y) = InR (fmap f y) diff --git a/libraries/base/changelog.md b/libraries/base/changelog.md index 515e398798..a11b059000 100644 --- a/libraries/base/changelog.md +++ b/libraries/base/changelog.md @@ -31,6 +31,11 @@ as well as [the migration guide](https://github.com/haskell/core-libraries-committee/blob/main/guides/export-lifta2-prelude.md) * Update to Unicode 15.0.0. * Add `Eq` and `Ord` instances for `Generically1`. + * Relax instances for Functor combinators; put superclass on Class1 and Class2 + to make non-breaking. See [CLC + #10](https://github.com/haskell/core-libraries-committee/issues/10) for the + related discussion, as well as [the migration + guide](https://github.com/haskell/core-libraries-committee/blob/main/guides/functor-combinator-instances-and-class1s.md). ## 4.17.0.0 *August 2022* |