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{-# LANGUAGE DefaultSignatures #-}
{-# LANGUAGE DeriveAnyClass #-}
{-# LANGUAGE DeriveGeneric #-}
{-# LANGUAGE FlexibleContexts #-}
{-# LANGUAGE TypeFamilies #-}
{-# LANGUAGE TypeOperators #-}
{-# LANGUAGE UndecidableInstances #-}
module T10361b where
import GHC.Generics
---------------------------------------------------------------------
class Convert a where
type Result a
type instance Result a = GResult (Rep a)
convert :: a -> Result a
default convert
:: (Generic a, GConvert (Rep a), Result a ~ GResult (Rep a))
=> a -> Result a
convert x = gconvert (from x)
instance Convert Float where
type Result Float = Float
convert = id
instance Convert Int where
type Result Int = Int
convert = id
---------------------------------------------------------------------
class GConvert f where
type GResult f
gconvert :: f p -> GResult f
instance (Convert c) => GConvert (K1 i c) where
type GResult (K1 i c) = Result c
gconvert (K1 x) = convert x
instance (GConvert f) => GConvert (M1 i t f) where
type GResult (M1 i t f) = GResult f
gconvert (M1 x) = gconvert x
instance (GConvert f, GConvert g) => GConvert (f :*: g) where
type GResult (f :*: g) = (GResult f, GResult g)
gconvert (x :*: y) = (gconvert x, gconvert y)
---------------------------------------------------------------------
data Data1 = Data1 Int Float
deriving (Generic)
instance Convert Data1
val :: (Int, Float)
val = convert $ Data1 0 0.0
data Data2 = Data2 Int Float
deriving (Generic, Convert)
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