[GHC] #11551: Get doctests into testsuite

[GHC]

#11551: Get doctests into testsuite
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        Reporter:  lwm               |                Owner:
            Type:  task              |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Core Libraries    |              Version:  7.10.3
      Resolution:                    |             Keywords:
                                     |  documentation, doctest
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Documentation     |  Unknown/Multiple
  bug                                |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by bgamari):

 lwm, is the trouble just integration into the build system or is there a
 deeper issue here? I quickly tried running `doctest` on some modules in
 `base` and very quickly ran into issues with multiple `base` versions
 (e.g. GHC desugared `do` syntax to imply a constraint of the `Monad` class
 provided by the compiler, not the `Monad` class provided by the `base`
 library which I was building.

 This suggests to me that even getting `doctest` running against `base`
 will take some effort by someone. Have you had different experiences, lwm?

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11551#comment:2>
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