[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 JulianLeviston):

 AFAICS, the only use-sites for `mkFractionalLit` are in HsSync/Convert.hs
 for the above function and also `cvtLit`.

 Does anyone have any thoughts about what a good approach to doing this
 might be? Should I be changing `mkFractionalLit` to `Integer -> Integer ->
 FractionalLit` or leave it as `Real a => a -> FractionalLit` as it already
 is? (the latter would imply doing some conversion to the number, the
 former would indicate the same conversion being moved up into the TH
 related code).

 Thoughts?

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15646#comment:28>
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