[GHC] #15522: Cannot bind symbolic names in a rule

[GHC]

#15522: Cannot bind symbolic names in a rule
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           Reporter:  goldfire       |             Owner:  (none)
               Type:  bug            |            Status:  new
           Priority:  normal         |         Milestone:  8.6.1
          Component:  Documentation  |           Version:  8.4.3
           Keywords:                 |  Operating System:  Unknown/Multiple
       Architecture:                 |   Type of failure:  None/Unknown
  Unknown/Multiple                   |
          Test Case:                 |        Blocked By:
           Blocking:                 |   Related Tickets:
Differential Rev(s):                 |         Wiki Page:
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 I assumed the following would be accepted:

 {{{
 {-# RULES "blah" forall (+++). id (+++) = (+++) #-}
 }}}

 But it's not, as the parser doesn't like my `+++`. I find this
 inconsistent with the way that GHC normally treats term-level variables,
 which can generally be symbolic.

 That said, I have no need for this feature, and allowing it creates more
 headaches (it potentially creates parsing challenges, especially with
 #2600; and soon people will want to specify fixities). I thus propose
 simply to document that we don't allow it and move on.

 If you agree (for any definition of "you"), please post, as I'd love other
 opinions.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15522>
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