seq as type class method
ndmitchell at gmail.com
Mon Nov 9 06:32:01 EST 2009
> | -- | This makes GHC's optimiser happier; it sometimes produces really bad
> | -- code for single-method dictionaries
> | --
> | unlifted_dummy :: a
> | unlifted_dummy = error "unlifted_dummy"
> If you have such cases, please please boil it down and file it as a bug. We should get *better* code not worse for
> single-method dictionaries.
I benchmarked this when doing the Uniplate work - 1-member classes
gave a noticeable performance benefit over 2 or more members. I think
it was 6% or so in my setup, and as a result Uniplate has a single
member type class.
More information about the Libraries