Runing type functions is too slow
Gergo reports, prompted by this question on Stack Overflow.
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 attached as slow1.hs and slow2.hs below.
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, respectively!
Is this some known regression, something surprising, or is 'perf' simply not the right build flavour for this kind of comparison?