[GHC] #13734: Code requires ScopedTypeVariables, possibly erroneously

[GHC]

#13734: Code requires ScopedTypeVariables, possibly erroneously
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        Reporter:  Iceland_jack      |                Owner:  (none)
            Type:  bug               |               Status:  closed
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.0.1
      Resolution:  invalid           |             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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Changes (by simonpj):

 * status:  new => closed
 * resolution:   => invalid


Comment:

 Without `ScopedTypeVariables` the type variables mentioned in are, well,
 not in scope.  (As specified in the Haskell 2010 report.)  We get
 {{{
 T13734.hs:16:18: error: Not in scope: type variable ‘a’
    |
 16 |   size _ = size @a  + size @b
    |                  ^
 }}}


 So I agree with Ryan.  Please re-open if you disagree.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13734#comment:2>
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