[GHC] #10067: The Read Integer instance is too slow

[GHC]

#10067: The Read Integer instance is too slow
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        Reporter:  redneb            |                   Owner:
            Type:  feature request   |                  Status:  patch
        Priority:  high              |               Milestone:  7.10.1
       Component:  Core Libraries    |                 Version:  7.11
      Resolution:                    |                Keywords:
Operating System:  Unknown/Multiple  |            Architecture:
 Type of failure:  Runtime           |  Unknown/Multiple
  performance bug                    |               Test Case:
      Blocked By:                    |                Blocking:
 Related Tickets:                    |  Differential Revisions:  Phab:D645
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Comment (by hvr):

 Replying to [comment:6 redneb]:
 > Herbert, do you have any objection moving the `Read Natural` instance to
 `GHC.Read`? This will make it easier to treat `Natural` like any other
 type in the future.

 I have no hard objection, only a soft one:

 Right now, `GHC.Natural` is a neat independent leaf-module in the import-
 graph. By defining the Natural instance in `GHC.Read`, it would lose that
 property, and I'm not sure what else you'd need to transform in the import
 graph to make that happen.

 Is there a real benefit from moving the instance from the data-type module
 to the class module? Or is this just about aesthetics?

 > Otherwise, there will be an module import cycle and will require an hs-
 boot file.

 In any case, if possible make the `Natural` change a separate commit if
 possible so we can see more easily what import-related shuffling was
 needed to accomplish that.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10067#comment:9>
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