{-# LANGUAGE MonoLocalBinds #-}

import Type.Reflection
import Data.Type.Equality

data Eq3 = Equal | NotEqual | NotComparable
  deriving (Show, Eq, Enum, Bounded)

dynamicEq' :: (Eq a) => Maybe (a :~: b) -> a -> b -> Eq3
dynamicEq' Nothing _ _ = NotComparable
dynamicEq' (Just Refl) a b = if a == b then Equal else NotEqual
dynamicEq :: (Eq a, Typeable a, Typeable b) => a -> b -> Eq3
dynamicEq a b = dynamicEq' (testEquality (typeOf a) (typeOf b)) a b

scalar :: [Char]
scalar = "Hello"

maybe1 :: Maybe [Char]
maybe1 = Just "Hello"

maybe2 :: Maybe (Maybe [Char])
maybe2 = Just (Just "Hello")

main = do 
  print $ dynamicEq scalar "Hello"
  print $ dynamicEq maybe1 (Just "Hello")
  print $ dynamicEq maybe2 (Just (Just "Hello"))
  putStrLn ""
  print $ dynamicEq scalar "Jello"
  print $ dynamicEq maybe1 (Just "Mellow")
  print $ dynamicEq maybe2 (Just (Just "Fellow"))
  putStrLn ""
  print $ dynamicEq scalar maybe1
  print $ dynamicEq maybe1 maybe2
  print $ dynamicEq scalar maybe2