[GHC] #12447: Pretty-printing of equality `~` without parentheses

[GHC]

#12447: Pretty-printing of equality `~` without parentheses
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        Reporter:  Iceland_jack      |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              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):

 It appears that this was fixed in GHC 8.2.2, since now the type signature
 has parentheses where it didn't before:

 {{{
 $ ghci -XTypeApplications Bug.hs
 GHCi, version 8.4.2: http://www.haskell.org/ghc/  :? for help
 Loaded GHCi configuration from /home/rgscott/.ghci
 [1 of 1] Compiling Main             ( Bug.hs, interpreted )
 Ok, one module loaded.
 λ> :t deferEither @(_ ~ _)
 deferEither @(_ ~ _)
   :: (Typeable w1, Typeable w2) =>
      proxy (w1 ~ w2) -> ((w1 ~ w2) => r) -> Either String r
 }}}

 I'll unmark the test case from its current `expected_broken` state.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12447#comment:4>
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