[GHC] #9872: Runing type functions is too slow
GHC
ghc-devs at haskell.org
Mon Dec 8 11:45:08 UTC 2014
#9872: Runing type functions is too slow
-------------------------------------+-------------------------------------
Reporter: simonpj | Owner:
Type: bug | Status: new
Priority: normal | Milestone:
Component: Compiler | Version: 7.8.3
Keywords: | Operating System:
Architecture: Unknown/Multiple | Unknown/Multiple
Difficulty: Unknown | Type of failure:
Blocked By: | None/Unknown
Related Tickets: | Test Case:
| Blocking:
| Differential Revisions:
-------------------------------------+-------------------------------------
Gergo reports, prompted by
[http://stackoverflow.com/questions/26538595/more-efficient-type-level-
computations-using-type-families 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?
--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9872>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
More information about the ghc-tickets
mailing list