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|
{-# LANGUAGE CPP #-}
{-|
Module: Data.Functor.Classes.Generic
Copyright: (C) 2015-2016 Edward Kmett, Ryan Scott
License: BSD-style (see the file LICENSE)
Maintainer: Ryan Scott
Stability: Provisional
Portability: GHC
Functions to generically derive 'C.Eq1', 'C.Ord1', 'C.Read1', and 'C.Show1'
instances from "Data.Functor.Classes".
-}
module Data.Functor.Classes.Generic
( -- * Options
Options(..)
, defaultOptions
, latestGHCOptions
#if defined(TRANSFORMERS_FOUR)
-- * 'Eq1'
, eq1Default
, eq1Options
-- * 'Ord1'
, compare1Default
, compare1Options
-- * 'Read1'
, readsPrec1Default
, readsPrec1Options
-- * 'Show1'
, showsPrec1Default
, showsPrec1Options
#else
-- * 'Eq1'
, liftEqDefault
, liftEqOptions
-- * 'Ord1'
, liftCompareDefault
, liftCompareOptions
-- * 'Read1'
, liftReadsPrecDefault
, liftReadsPrecOptions
-- * 'Show1'
, liftShowsPrecDefault
, liftShowsPrecOptions
#endif
-- * 'GenericFunctorClasses'
, FunctorClassesDefault(..)
-- * Example
-- $example
) where
import qualified Data.Functor.Classes as C ()
import Data.Functor.Classes.Generic.Internal
#undef MIN_VERSION_transformers
{- $example
The most straightforward way to use the defaults in this module is to use
@DerivingVia@ on GHC 8.6 or later. For example:
@
{-# LANGUAGE DeriveGeneric, DerivingVia #-}
import Data.Functor.Classes
import Data.Functor.Classes.Generic
import GHC.Generics
data Pair a = Pair a a
deriving stock Generic1
deriving (Eq1, Ord1, Read1, Show1)
via FunctorClassesDefault Pair
@
If using an older version of GHC, then one can also define instances manually.
This is slightly trickier to accomplish since this module exports different
functions depending on which version of @transformers@ this library is built
against. Here is an example of how to define instances manually:
@
{-# LANGUAGE CPP, DeriveGeneric #-}
import Data.Functor.Classes
import Data.Functor.Classes.Generic
import GHC.Generics
data Pair a = Pair a a deriving Generic1
instance 'C.Eq1' Pair where
\#if MIN_VERSION_transformers(0,4,0) && !(MIN_VERSION_transformers(0,5,0))
'C.eq1' = 'eq1Default'
\#else
'C.liftEq' = 'liftEqDefault'
\#endif
instance 'C.Ord1' Pair where
\#if MIN_VERSION_transformers(0,4,0) && !(MIN_VERSION_transformers(0,5,0))
'C.compare1' = 'compare1Default'
\#else
'C.liftCompare' = 'liftCompareDefault'
\#endif
instance 'C.Read1' Pair where
\#if MIN_VERSION_transformers(0,4,0) && !(MIN_VERSION_transformers(0,5,0))
'C.readsPrec1' = 'readsPrec1Default'
\#else
'C.liftReadsPrec' = 'liftReadsPrecDefault'
\#endif
instance 'C.Show1' Pair where
\#if MIN_VERSION_transformers(0,4,0) && !(MIN_VERSION_transformers(0,5,0))
'C.showsPrec1' = 'showsPrec1Default'
\#else
'C.liftShowsPrec' = 'liftShowsPrecDefault'
\#endif
@
-}
|
