We can't just upgrade those classes to be type family based, as this
destroys their support for polymorphic recursion.
We could write another class though.
The question is if that class belongs in base or in some other package, as
it takes is pretty far afield of anything purporting to be portable.
On Wed, Sep 11, 2013 at 9:35 AM, Duncan Coutts wrote: 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 http://www.haskell.org/haskellwiki/Library_submissions so I
suppose it would come down to talking one of them into taking the patch. Yes, I'm happy to consider pull requests. https://github.com/haskell/bytestring/ 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. Duncan