[GHC] #11835: ApplicativeDo failed to desugar last line with pure $ <expr>

[GHC]

#11835: ApplicativeDo failed to desugar last line with pure $ <expr>
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        Reporter:  Cosmia            |                Owner:  simonmar
            Type:  bug               |               Status:  merge
        Priority:  normal            |            Milestone:  8.0.2
       Component:  Compiler          |              Version:  8.0.1-rc2
      Resolution:                    |             Keywords:  ApplicativeDo
Operating System:  MacOS X           |         Architecture:
 Type of failure:  GHC rejects       |  Unknown/Multiple
  valid program                      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #11607            |  Differential Rev(s):  Phab:D2345
       Wiki Page:                    |
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Comment (by Simon Marlow <marlowsd@…>):

 In [changeset:"0ba34b6bac988228948c65ae11d9e08afe82c878/ghc" 0ba34b6/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="0ba34b6bac988228948c65ae11d9e08afe82c878"
 ApplicativeDo: allow "return $ e"

 Summary:
 There's a precedent for special-casing $, as we already have special
 typing rules for it.

 Test Plan: validate; new test cases

 Reviewers: ezyang, austin, niteria, bgamari, simonpj, erikd

 Subscribers: thomie

 Differential Revision: https://phabricator.haskell.org/D2345

 GHC Trac Issues: #11835
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11835#comment:9>
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