{-# LANGUAGE GHC2024 #-}
{-# LANGUAGE AllowAmbiguousTypes #-}
{-# LANGUAGE PatternSynonyms #-}
{-# LANGUAGE RequiredTypeArguments #-}

import Data.Typeable (Typeable, cast)

data SomeStorable where Storage :: MyStorable a => a -> SomeStorable
class Typeable a => MyStorable a where sizeOf :: forall b -> b ~ a => Int
instance MyStorable Bool where sizeOf _ = 1
instance MyStorable Int where sizeOf _  = 8

testMe :: forall a. MyStorable a => a -> Int;   testMe _ = sizeOf a
testMe2 :: forall a. MyStorable a => Int;       testMe2 = sizeOf a
testMe3 :: SomeStorable -> Int;                 testMe3 (Storage (_ :: a)) = sizeOf a
pattern MyInt :: Int;                           pattern MyInt = 42

main :: IO ()
main = do
    print $ testMe True
    print $ testMe MyInt
    print $ testMe2 @Bool
    print $ testMe2 @Int
    print $ testMe3 (Storage True)
    print $ testMe3 (Storage MyInt)