[GHC] #10603: Output of -ddump-splices is parenthesized incorrectly

4 Jul 2015


      #10603: Output of -ddump-splices is parenthesized incorrectly
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              Reporter:              |             Owner:
  RyanGlScott                        |            Status:  new
                  Type:  bug         |         Milestone:
              Priority:  normal      |           Version:  7.10.1
             Component:  Template    |  Operating System:  Unknown/Multiple
  Haskell                            |   Type of failure:  Other
              Keywords:              |        Blocked By:
          Architecture:              |   Related Tickets:
  Unknown/Multiple                   |
             Test Case:              |
              Blocking:              |
Differential Revisions:              |
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 Sometimes, Template Haskell splices lack necessary parentheses. Minimal
 example:

 {{{
 $ ghci -XTemplateHaskell -ddump-splices
 GHCi, version 7.10.1: http://www.haskell.org/ghc/  :? for help
 λ> :t $([| case Just 'a' of Just a -> Just ((\x -> x) a) |])
 <interactive>:1:3-53: Splicing expression
     [| case Just 'a' of {
          Just a_avZ -> Just ((\ x_aw0 -> x_aw0) a_avZ) } |]
   ======>
     case Just 'a' of {
       Just a_a3wI -> Just (\ x_a3wJ -> x_a3wJ a_a3wI) }
 $([| case Just 'a' of Just a -> Just ((\x -> x) a) |])
   :: Maybe Char
 }}}

 The suspect part is {{{case Just 'a' of { Just a_a3wI -> Just (\ x_a3wJ ->
 x_a3wJ a_a3wI) } }}}, which should be {{{case Just 'a' of { Just a_a3wI ->
 Just ((\ x_a3wJ -> x_a3wJ) a_a3wI) } }}}.

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Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10603
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