[GHC] #9478: Partial type signatures

[GHC]

#9478: Partial type signatures
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        Reporter:  simonpj           |                Owner:
            Type:  feature request   |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  7.8.2
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:  partial-
                                     |  sigs/should_compile/PatBind2
                                     |  partial-
                                     |  sigs/should_compile/EqualityConstraint
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):  Phab:D168
       Wiki Page:                    |
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Comment (by Simon Peyton Jones <simonpj@…>):

 In [changeset:"e24b50c3a70a247a4695a80aceba0cf351eb1e9e/ghc"
 e24b50c3/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="e24b50c3a70a247a4695a80aceba0cf351eb1e9e"
 Use partial-sig constraints as givens

 In TcSimplify.simplifyInfer, use the context of a partial type
 signature as 'givens' when simplifying the inferred constraints of the
 group.  This way we get maximum benefit from them.  See
 Note [Add signature contexts as givens].

 This (finally) fixes test EqualityConstraints in Trac #9478.

 And it's a nice tidy-up.
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9478#comment:8>
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