38 lines
966 B
Haskell
38 lines
966 B
Haskell
{-# LANGUAGE TypeOperators, FlexibleContexts #-}
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{- | Pulled from
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https://stackoverflow.com/questions/10112733/haskell-simple-constructor-comparison-function
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-}
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module SameConstr where
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import GHC.Generics
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import Data.Function (on)
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--class EqC a where
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-- eqConstr :: a -> a -> Bool
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-- default eqConstr :: (Generic a, GEqC (Rep a)) => a -> a -> Bool
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-- eqConstr = geqConstr `on` from
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eqConstr :: (Generic a, GEqC (Rep a)) => a -> a -> Bool
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eqConstr = geqConstr `on` from
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class GEqC f where
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geqConstr :: f p -> f p -> Bool
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{-# INLINE geqConstr #-}
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geqConstr _ _ = True
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instance GEqC f => GEqC (M1 i c f) where
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{-# INLINE geqConstr #-}
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geqConstr (M1 x) (M1 y) = geqConstr x y
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instance GEqC (K1 i c)
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instance GEqC (f :*: g)
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instance GEqC U1
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instance GEqC V1
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instance (GEqC f, GEqC g) => GEqC (f :+: g) where
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{-# INLINE geqConstr #-}
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geqConstr (L1 x) (L1 y) = geqConstr x y
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geqConstr (R1 x) (R1 y) = geqConstr x y
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geqConstr _ _ = False
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