[GHC] #9194: Remove magic parsing of (~)

[GHC]

#9194: Remove magic parsing of (~)
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        Reporter:  goldfire          |            Owner:
            Type:  bug               |           Status:  new
        Priority:  normal            |        Milestone:
       Component:  Compiler          |          Version:  7.8.2
      Resolution:                    |         Keywords:
Operating System:  Unknown/Multiple  |     Architecture:  Unknown/Multiple
 Type of failure:  None/Unknown      |       Difficulty:  Unknown
       Test Case:                    |       Blocked By:
        Blocking:                    |  Related Tickets:
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Comment (by goldfire):

 Replying to [comment:2 simonpj]:
 > Yes, I suspect that `(~)` pre-dated `-XTypeOperators`.

 And, crucially, allowing type operators to skip the opening colon.

 Your comment does make me think that this change would then require users
 to specify `TypeOperators` whenever they use `(~)`. This would be a
 breaking change that would likely affect a lot of code, and perhaps for
 little gain. We could just special-case `(~)` not to require
 `TypeOperators`, but is that any better than the status quo?

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9194#comment:3>
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