Re: add concatMapM to base in control.monad

That does seem nice. I don’t actually have a horse in this race mind you , I was merely relaying a privately communicated from a friend proposal for feedback about its merits etc. On Fri, Feb 8, 2019 at 12:57 PM Evan Laforge wrote:

As long as we're playing the permutation game, I also frequently use mconcatMap, and mconcatMapM. Actually, my concatMapM is secretly '(Monad m, Monoid b) => (a -> m b) -> [a] -> m b', but I suppose you could argue that's inconsistent with the existing naming scheme.

I guess I don't mind it because unlike the generalization of [a] to Foldable a, I haven't had ambiguity problems with generalizing [a] to Monoid a. Just personal experience though.

On Fri, Feb 8, 2019 at 9:04 AM Carter Schonwald wrote:

...

friend asked me to raise this

previously https://ghc.haskell.org/trac/ghc/ticket/2042 seems like it iddn't happen last time because base lived outside of ghc?

-- | The 'concatMapM' function generalizes 'concatMap' to arbitrary

monads.

...

concatMapM :: (Monad m) => (a -> m [b]) -> [a] -> m [b] concatMapM f xs = liftM concat (mapM f xs)

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