[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
-------------------------------------+-------------------------------------
        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:  #5692             |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by JulianLeviston):

 Ah, after reporting those problems, I thought to myself... "let's try re-
 running `./boot` and `./configure` after moving the definitions of
 `mkRational`, `mkRationalWithExponentBase`, `FractionalExponentBase` and
 `rationalFromFractionalLit` to `GHC.Real` again to see if it actually
 bootstraps the files like I thought it might, and it seems it did (I
 obviously still have a lot to learn ;-)).

 Still, got many other compiler errors, but it at least it seems to be
 doing the right thing. I'm still fairly unsure about how exactly I can
 extract all the pieces I need to to put these functions into `GHC.Real`
 (or somewhere available)...

 Here are the errors (which make sense):

 {{{
 libraries/base/GHC/Real.hs:832:13: error:
     Not in scope: type constructor or class ‘Data’
     |
 832 |   deriving (Data, Show)
     |             ^^^^

 libraries/base/GHC/Real.hs:841:30: error:
     Not in scope: type constructor or class ‘FractionalLit’
     Perhaps you meant ‘Fractional’ (line 194)
     |
 841 | rationalFromFractionalLit :: FractionalLit -> Rational
     |                              ^^^^^^^^^^^^^

 libraries/base/GHC/Real.hs:842:28: error:
     Not in scope: data constructor ‘FL’
     Perhaps you meant ‘F#’ (imported from GHC.Base)
     |
 842 | rationalFromFractionalLit (FL _ _ i e expBase) =
     |                            ^^

 libraries/base/GHC/Real.hs:844:28: error:
     Not in scope: data constructor ‘THFL’
     |
 844 | rationalFromFractionalLit (THFL _ _ r) = r
     |                            ^^^^
 make[1]: *** [libraries/base/dist-install/build/GHC/Real.o] Error 1
 make: *** [all] Error 2

 }}}

 So, I'll keep pottering along and see if I can't make it compile.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15646#comment:68>
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