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{-# LANGUAGE CPP #-}
module Control.Applicative.OrphansSpec (main, spec) where
import Test.Hspec
import Control.Applicative
import Data.Orphans ()
import Data.Monoid
import Prelude
-- simplest one to use
newtype Identity a = Identity { runIdentity :: a }
instance Functor Identity where
fmap f = Identity . f . runIdentity
instance Applicative Identity where
pure = Identity
Identity f <*> x = f <$> x
instance Monad Identity where
#if !(MIN_VERSION_base(4,11,0))
return = Identity
#endif
m >>= k = k (runIdentity m)
main :: IO ()
main = hspec spec
spec :: Spec
spec = do
describe "Monoid (Const a b)" $ do
it "mempty returns an empty const" $
getConst (mempty :: (Const String Int)) `shouldBe` ""
it "mappends const part" $
getConst ((Const "aaa" :: Const String Int) `mappend` (Const "bbb" :: Const String Int))
`shouldBe` "aaabbb"
describe "Monad (WrappedMonad m)" $
it "allows to use a Monad interface in a WrappedMonad" $
(runIdentity . unwrapMonad
$ (WrapMonad (return 1 :: Identity Int))
>> (WrapMonad (return 2 :: Identity Int)))
`shouldBe` (2::Int)
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