mapM_ for bytestring

Duncan Coutts duncan.coutts at
Wed Sep 11 15:35:05 CEST 2013

On Thu, 2013-09-05 at 18:51 -0400, Edward Kmett wrote:
> The maintainers for bytestring are still listed as Don Stewart and Duncan
> Coutts on the package, and it doesn't seem to fall the list of core
> packages per so I
> suppose it would come down to talking one of them into taking the patch.

Yes, I'm happy to consider pull requests.

I should say that I start off sceptical about any additions to this API.
As Raymond Chen says, each new feature starts off with -100 points.

For mapM etc, personally I think a better solution would be if
ByteString and Text and other specialised containers could be an
instance of Foldable/Traversable. Those classes define mapM etc but
currently they only work for containers that are polymorphic in their
elements, so all specialised containers are excluded. I'm sure there
must be a solution to that (I'd guess with type families) and that would
be much nicer than adding mapM etc to bytestring itself. We would then
just provide efficient instances for Foldable/Traversable.


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