[GHC] #11451: Inconsistent warnings for unused binders

[GHC]

#11451: Inconsistent warnings for unused binders
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        Reporter:  simonpj           |                Owner:
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  7.10.3
      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 ekmett):

 It is worth noting that we've developed a sort of culture of signaling
 intent with the names of those variables, when a Haskell programmer sees
 'a' or 'b' they usually expect something of kind *, f as something of kind
 * -> *, etc.

 Is it right? Arguably not, but it is useful. If we're forced to replace
 all of those with _'s a lot of signal will be lost.

 There is also a concern that a warning here is something users won't be
 able to act on if they want to work at all on older compilers that didn't
 allow _s there.

 I don't have a concrete counter-proposal, but I do feel ill at ease.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11451#comment:8>
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