this looks quite pretty, though I must admit that im not the most savvy at quantified constraints yet

wouldn't this newtype also benefit from a semigroup and monoid instance too? (or am I overlooking some reason why you can't do them too?)

On Fri, Feb 15, 2019 at 7:05 PM theindigamer <theindigamer15@gmail.com> wrote:

Thoughts on adding a newtype with the following Alternative instance?

(The name chosen is a placeholder, I don't have any particular preference).

newtype Mon f a = Mon { unMon :: f a } 

instance (forall a. Monoid (f a)) => Alternative (Mon f) where
  empty = Mon mempty
  (<|>) (Mon m1) (Mon m2) = Mon (m1 <> m2)

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