Add MonadIO instance for EIO

[JonathanLorimer]

I am not sure if this is possible. The first hurdle is getting an applicative and monad instance. The naive applicative implementation gives this error:

src/EIO.hs:54:15-54: error:
    • Couldn't match type ‘e’ with ‘e <> e’
      Expected: EIO e b
        Actual: EIO (e <> e) b
      ‘e’ is a rigid type variable bound by
        the instance declaration
        at src/EIO.hs:53:10-28
    • In the expression: af >>= \ f -> ax >>= \ x -> return (f x)
      In an equation for ‘<*>’:
          af <*> ax = af >>= \ f -> ax >>= \ x -> return (f x)
      In the instance declaration for ‘Applicative (EIO e)’
    • Relevant bindings include
        ax :: EIO e a (bound at src/EIO.hs:54:10)
        af :: EIO e (a -> b) (bound at src/EIO.hs:54:3)
        (<*>) :: EIO e (a -> b) -> EIO e a -> EIO e b
          (bound at src/EIO.hs:54:6)
   |
54 |   af <*> ax = af >>= \ f -> ax >>= \ x -> return (f x)
   |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^