Discussion: reconsider lens-like exports from containers

[rf at rufflewind.com]

On Tue, Apr 26, 2016, at 15:03, David Feuer wrote:
> Way back when, Shachaf Ben-Kiki suggested an efficient implementation
> of `at` for Data.Map in
> https://mail.haskell.org/pipermail/libraries/2013-May/019761.html but
> that was never approved for inclusion.

Funny thing, I just tried doing that not to long ago with `at`:

https://github.com/haskell/containers/pull/192

In the end, the results were mixed.  It was a small optimization in some
situations, and a moderate pessimization in others (esp. when the
Functor becomes too complex for GHC to optimize).

--
RF