[GHC] #15646: ghci takes super long time to find the type of large fractional number

[GHC]

#15646: ghci takes super long time to find the type of large fractional number
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        Reporter:  Johannkokos       |                Owner:
                                     |  JulianLeviston
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:  8.6.1
       Component:  GHCi              |              Version:  8.4.3
      Resolution:                    |             Keywords:  newcomer
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Compile-time      |  Unknown/Multiple
  performance bug                    |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by osa1):

 I think profiled GHC may not help that much because we already have a good
 idea of what's going wrong.

 I'd print `litI` and `litE` in the desugaring code you showed in
 comment:46 and see if any of the integers are huge. Remember that the root
 cause is that we build huge integers in compile time and we're trying to
 avoid that. If this is still taking too long then we somehow still build
 huge integers in compile time. Given that we only build two integers, one
 them them should be the culprit. Printing would show us which one, and
 then we can figure out the rest.

 Can you push your code on a git repo and give us the remote/branch?

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15646#comment:50>
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