Overlapping instances by turning Monads into Semigroups

Question

Monads define Semigroups via

instance Monad m => Semigroup (m a) where
    (<>) = (>>)

using FlexibleInstances.

If I wanted to make Maybe a into a Semigroup in that way I would run into an Intance overlap, because Data.Semigroup defines an

instance Semigroup a => Semigroup (Maybe a)

What is the Haskell-Way to resolve something like that?

Answer 1

The common way in which these problems are solved is with a newtype wrapper. You wouldn't define an instance Semigroup (m a), but rather

newtype WrappedMonad m a = WrappedMonad { getWrappedMonad :: m a }

instance Monad m => Semigroup (WrappedMonad m a) where
    WrappedMonad a <> WrappedMonad b = WrappedMonad (a >> b)