We deliberately took no more symbols than we needed in 7.10 from Prelude as part of the Foldable/Traversable Proposal. There are multiple combinators in Data.Foldable and Data.Traversable that we do not export. traverse_ is one of them as, strictly speaking, traverse_ was a symbol we didn't have to take.

If we had would anybody have complained any more loudly? Not sure... but it was a deliberate choice to not bring in any symbols into Prelude that weren't already there that weren't part of the definition of a class or needed to define instances that already existed.

-Edward

On Mon, Mar 30, 2015 at 11:33 PM, Fumiaki Kinoshita <fumiexcel@gmail.com> wrote:

Well, I see. It'd be nice.

That aside, the absence of traverse_ doesn't seem to be intended (even the documentation for mapM_ says "mapM_ is just traverse_"!)

2015-03-30 16:54 GMT+09:00 Herbert Valerio Riedel <hvr@gnu.org>:

On 2015-03-30 at 07:05:56 +0200, Fumiaki Kinoshita wrote:

[...]

> I found out that (<>) (in Data.Monoid) is missing, also. It would be nice
> to reexamine Prelude to export things we want to export.

Fwiw, (<>) was actually left-out as it wasn't required (it's just a an
alias for `mappend`), *and* to keep our options open (or at least not
make it more difficult) in terms of possible migration-plans available
for the case we'd be moving 'Semigroup' to base/Prelude at some point in
the future.

_______________________________________________
ghc-devs mailing list
ghc-devs@haskell.org
http://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-devs