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Diffstat (limited to 'testsuite/tests/generics/GEq/GEq2.hs')
-rw-r--r-- | testsuite/tests/generics/GEq/GEq2.hs | 78 |
1 files changed, 78 insertions, 0 deletions
diff --git a/testsuite/tests/generics/GEq/GEq2.hs b/testsuite/tests/generics/GEq/GEq2.hs new file mode 100644 index 0000000000..ac825aa71f --- /dev/null +++ b/testsuite/tests/generics/GEq/GEq2.hs @@ -0,0 +1,78 @@ +{-# LANGUAGE TypeOperators, DefaultSignatures, FlexibleInstances, DeriveGeneric #-} +{-# LANGUAGE FlexibleContexts #-} + +module Main where + +import GHC.Generics hiding (C, D) + +class GEq' f where + geq' :: f a -> f a -> Bool + +instance GEq' U1 where + geq' _ _ = True + +instance (GEq c) => GEq' (K1 i c) where + geq' (K1 a) (K1 b) = geq a b + +-- No instances for P or Rec because geq is only applicable to types of kind * + +instance (GEq' a) => GEq' (M1 i c a) where + geq' (M1 a) (M1 b) = geq' a b + +instance (GEq' a, GEq' b) => GEq' (a :+: b) where + geq' (L1 a) (L1 b) = geq' a b + geq' (R1 a) (R1 b) = geq' a b + geq' _ _ = False + +instance (GEq' a, GEq' b) => GEq' (a :*: b) where + geq' (a1 :*: b1) (a2 :*: b2) = geq' a1 a2 && geq' b1 b2 + + +class GEq a where + geq :: a -> a -> Bool + default geq :: (Generic a, GEq' (Rep a)) => a -> a -> Bool + geq x y = geq' (from x) (from y) + + +-- Base types instances (ad-hoc) +instance GEq Char where geq = (==) +instance GEq Int where geq = (==) +instance GEq Float where geq = (==) +{- +-- Generic instances +instance (GEq a) => GEq (Maybe a) +instance (GEq a) => GEq [a] +-} + +data C = C0 | C1 + deriving Generic + +data D a = D0 | D1 { d11 :: a, d12 :: (D a) } + deriving Generic + +data (:**:) a b = a :**: b + deriving Generic + +-- Example values +c0 = C0 +c1 = C1 + +d0 :: D Char +d0 = D0 +d1 = D1 'p' D0 + +p1 :: Int :**: Char +p1 = 3 :**: 'p' + +-- Generic instances +instance GEq C +instance (GEq a) => GEq (D a) +instance (GEq a, GEq b) => GEq (a :**: b) + +-- Tests +teq0 = geq c0 c1 +teq1 = geq d0 d1 +teq2 = geq d0 d0 +teq3 = geq p1 p1 + +main = mapM_ print [teq0, teq1, teq2, teq3] |