performance regressions

Richard Eisenberg eir at
Sat Dec 13 15:03:15 UTC 2014

I think I've fixed this. I've pushed the fix to wip/rae, and waiting for validation results before pushing to master.

My hunch below was right -- it was the change to matchFam, which essentially evaluated type-level functions more strictly. I've now made it lazier again. I'd like to better understand the tradeoff here, and to see if there's a principled sweet spot. But that will happen in a few days.

Expect a push to master soon.

Again, sorry for the bother.


On Dec 13, 2014, at 8:32 AM, Joachim Breitner <mail at> wrote:

> Hi,
> Am Freitag, den 12.12.2014, 21:51 -0500 schrieb Richard Eisenberg:
>> Phab has shown up some performance regressions in my recent commits.
>> See The
>> failures except for haddock.base are new, and evidently my fault. They
>> didn't show up on Travis. Will look into it shortly, but I doubt over
>> the weekend.
> ghcspeed also observes this:
> Especially the T9872 benchmarks have a huge increase in allocations. But
> you seem to be aware of this, so that’s fine.
> Greetings,
> Joachim
> -- 
> Joachim “nomeata” Breitner
>  mail at joachim-breitner.de
>  Jabber: nomeata at  • GPG-Key: 0xF0FBF51F
>  Debian Developer: nomeata at
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