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{-# LANGUAGE AllowAmbiguousTypes #-}
module Spec.Functor ( laws )
where
import Clothes (F, H, FG(..), GH(..), NatTransf(..))
import Data.Functor.Barbie (FunctorB(..))
import Data.Typeable (Typeable, typeRep, Proxy(..))
import Test.Tasty(testGroup, TestTree)
import Test.Tasty.QuickCheck(Arbitrary(..), testProperty, (===))
laws
:: forall b
. ( FunctorB b
, Eq (b F), Eq (b H)
, Show (b F), Show (b H)
, Arbitrary (b F)
, Typeable b
)
=> TestTree
laws
= testGroup (show (typeRep (Proxy :: Proxy b)))
[ testProperty "bmap id = id" $ \b ->
bmap id b === (b :: b F)
, testProperty "bmap (f . g) = bmap f . bmap g)" $
\b (GH (NatTransf f)) (FG (NatTransf g)) ->
bmap (f . g) b === (bmap f . bmap g) (b :: b F)
]
|
