Performance regression on typechecking type families?
Dr. ERDI Gergo
gergo at erdi.hu
Sat Nov 29 10:17:30 UTC 2014
Prompted by this question:
I wrote some code today using closed type families and datakinds. Also, as
a baseline, I typechecked the code using open type families from
the original question.
The two files are here:
On GHC 7.8.3, typechecking took about 45 seconds for each. However, on a
'perf' build of GHC 7.9 d8c437b3, with ghc-stage2, the first one took 1m3s
and the second one 1m12s. A 40% and 60% increase in typechecking time,
Is this some known regression, something surprising, or is 'perf' simply
not the right build flavour for this kind of comparison?
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