Make Eq type class single method

Joachim Breitner mail at
Fri Oct 22 10:11:24 UTC 2021


Am Mittwoch, dem 20.10.2021 um 22:28 +0200 schrieb Joachim Breitner:
> nofib might be too specialized; I think “ghc compiling Cabal” is a good
> benchmark. I’ll do that eventually, if GHC’s CI doesn’t do that already
> for me (I’ll ask Ben what kind of infrastructure we have for that –
> doing it manually and correctly is tedious and error-prone), maybe
> tomorrow. 

Thanks for Mortiz Angerman for giving me access to a quiet machine.
Here my crude setup to measure the time it takes GHC to compiler Cabal:

$ for branch in ghc ghc-single-method-eq; do echo $branch; cd $branch; for i in 1 2 3 4 5; do /run/current-system/sw/bin/time _build/stage1/bin/ghc -hidir tmp -odir tmp -fforce-recomp +RTS -t -ttmp/ghc.log -RTS -ilibraries/Cabal/Cabal/src -XNoPolyKinds Distribution.Simple -O2 -v0; done; cd ..; done
128.67user 2.03system 2:10.60elapsed
128.92user 2.00system 2:10.76elapsed
129.36user 2.07system 2:11.30elapsed
128.83user 2.02system 2:10.71elapsed
128.76user 2.13system 2:10.71elapsed
128.14user 2.04system 2:10.02elapsed
128.14user 2.02system 2:10.00elapsed
127.68user 2.12system 2:09.64elapsed
128.10user 2.05system 2:10.02elapsed
129.23user 1.95system 2:11.05elapsed

I guess that means no significant improvement…

(Such measurements always leave me wondering if I draw the right
conclusions, and my setup is good. I crave for some expertly-setup
measurement system where I don't have to worry about that, and I simply
get a result.)


Joachim Breitner
  mail at

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