[GHC] #11765: Allow documentary type signatures

[GHC]

#11765: Allow documentary type signatures
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        Reporter:  dfeuer            |                Owner:
            Type:  feature request   |               Status:  new
        Priority:  normal            |            Milestone:  8.2.1
       Component:  Compiler (Type    |              Version:  7.10.3
  checker)                           |
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by dfeuer):

 Replying to [comment:1 simonpj]:
 > Not a bad idea; and easy to implement given syntax that everyone is
 happy with.  In SPECIALISE pragmas the type is inside the pragma, and this
 is a variant of `SPECIALISE`.
 >
 > Indeed, maybe it ''is'' `SPECIALISE`, except that GHC might notice that
 there was nothing to be gained from specialising and so discard the code
 and rule.

 It's certainly quite similar! It sometimes declines to generate code/rules
 (insufficient specialization, too complicated), and here we'd probably
 prefer to skip generation rather than generate and discard. But it seems
 likely that machinery could be shared.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11765#comment:2>
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