[GHC] #13177: Give Data.Functor.* its lifted void and unit

[GHC]

#13177: Give Data.Functor.* its lifted void and unit
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        Reporter:  Iceland_jack      |                Owner:
            Type:  feature request   |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  libraries/base    |              Version:  8.0.1
      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 RyanGlScott):

 Replying to [comment:4 Iceland_jack]:
 > Agreed but is merging them a realistic option?

 In the short term, probably not. But it is on my radar after ekmett
 pitched the idea in
 https://ghc.haskell.org/trac/ghc/ticket/11650#comment:11. It's possible
 that we might want to merge the datatypes in `GHC.Generics` with their
 `Data.Functor.*` counterparts someday with clever uses of pattern
 synonyms. I dunno.

 > > As another point of reference, the `trivia` package on Hackage calls
 lifted void and unit `Zero` and `One`, respectively.
 >
 > I like those names.

 If you like the names `Zero` and `One`, great! I don't think it'd be wise
 for me to just plop datatypes into `base` without warning, or else folks
 who care about this stuff might come after me with pitchforks :)

 That's why I always advise folks to consult the libraries mailing list if
 they're in doubt. It can be tedious, I know, but it's the best solution we
 have to make sure that what goes into the core libraries doesn't create a
 rift with those who actually use it.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13177#comment:5>
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