GHC 7.10 regression when using foldr

[Bryan O'Sullivan]

On Tue, Jan 20, 2015 at 3:45 AM, Edward Kmett <ekmett at gmail.com> wrote:

> Ultimately, there is, of course, a balancing act between flexibility and
> inference.
>
> I can at least say that the incident rate for cases seems to be very low,
> especially when it is contrasted against the pain users have had with using
> the existing Foldable/Traversable imports where virtually everything in
> them collided with less useful versions of the same combinator (e.g. mapM)
> from the Prelude that a dozen other modules (e.g. Control.Monad and
> virtually every module in mtl) insisted on re-exporting, making it a game
> of whack-a-mole to try to hide them.
>

For the record, it took me almost an hour to update attoparsec to fix all
the various regressions, or to put it more charitably changes, introduced
in GHC 7.10. I have twenty-something other packages to go through. I don't
keep track of the time sunk from release to release, but this feels
somewhat worse than average.

Basically, the more careful you are in writing a package, the more each
update of GHC and base costs in nickel-and-dime tweaks to keep a build
clean. It's not a very happy-making feedback loop. "Be a good citizen, and
your reward is to spend *even more* time cleaning up!"
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.haskell.org/pipermail/glasgow-haskell-users/attachments/20150120/4f74de5a/attachment.html>