mconcat on semigroups

[viglioni]

Ciao! How are you?

I was wondering if adding mconcat functions on SemiGroups using ReadonlyArrays would be something that makes sense in the library

import { reduce } from 'fp-ts/lib/ReadonlyArray'

interface Monoid<A> extends Semigroup<A> {
  readonly empty: A,
  readonly mconcat: ReadonlyArray<A> => A
}

// Example of monoid sum implementation
const mconcat = reduce(MonoidSum.empty, MonoidSum.concat)

(it's not a feature request exactly, I can try to create a PR with this new feat, I just want to know if this is desirable)

[gcanti]

There's concatAll

[viglioni]

grazie!