[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:                    |  Differential Rev(s):
       Wiki Page:                    |
-------------------------------------+-------------------------------------
Changes (by simonpj):

 * cc: goldfire (added)


Comment:

 I think the Right Thing is to make TH syntax look like Hs syntax.  After
 all, rational literals in TH are (as you show) subject to precisely the
 problem of this ticket, and are amenable to precisely the same solution.

 When we complete the Trees That Grow epic that equivalence will become
 true by construction.

 Richard Eisenberg is the TH tzar; let's ask him.  Generally we have
 changed the details of TH syntax in every GHC release, and I don't think
 it's a major source of complaints.

 To get rolling, though, you could do some approximate way of converting a
 `Rational` to  literal in the form we have mapped out here.  The passage
 through TH would not be fully faithful, but it'd be close.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15646#comment:30>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler