Add foldMapM to Data.Foldable

[Andreas Abel]

+1.

If I remember correctly, then Henning Thielemann has suggested this as 
the proper generalization of mapM_.

On 06.12.2017 15:28, Andrew Martin wrote:
> Several coworkers and myself have independently reinvented this function 
> several times:
> 
>      foldMapM :: (Foldable g, Monoid b, Monad m) => (a -> m b) -> g a -> m b
>      foldMapM f xs = foldlM (\b a -> mappend b <$> (f a)) mempty xs
> 
> I would like to propose that this be added to Data.Foldable. We have the 
> triplet foldr,foldl,foldMap in the Foldable typeclass itself, and 
> Data.Foldable provides foldrM and foldlM. It would be nice to provide 
> foldMapM for symmetry and because it seems to be useful in a variety of 
> applications.
> 
> -- 
> -Andrew Thaddeus Martin
> 
> 
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-- 
Andreas Abel  <><      Du bist der geliebte Mensch.

Department of Computer Science and Engineering
Chalmers and Gothenburg University, Sweden

andreas.abel at gu.se
http://www.cse.chalmers.se/~abela/