type family Or
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{-# LANGUAGE AllowAmbiguousTypes, TypeApplications, ScopedTypeVariables, TypeFamilies, DataKinds #-}
import Data.Typeable
typeName :: forall a. Typeable a => String
typeName = show . typeRep $ Proxy @a
type family Or (x :: Bool) (y:: Bool) :: Bool where
Or 'True y = 'True
Or 'False y = y
type family And (x :: Bool) (y:: Bool) :: Bool where
And 'True y = y
And 'False y = 'False
type T = Or 'True 'False
domeSomething :: Proxy 'True -> IO ()
domeSomething p = putStrLn $ show p
main = domeSomething (Proxy :: Proxy (Or 'False (And 'True 'True))) >> putStrLn "..."
five :: (a ~ Int) => a
five = 5
Haskell
INFO