[GHC] #10451: Constraint tuple regression in HEAD

[GHC]

#10451: Constraint tuple regression in HEAD
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        Reporter:  darchon           |                   Owner:
            Type:  bug               |                  Status:  new
        Priority:  normal            |               Milestone:
       Component:  Compiler          |                 Version:  7.11
      Resolution:                    |                Keywords:
Operating System:  Unknown/Multiple  |  ConstraintKinds
 Type of failure:  GHC rejects       |            Architecture:
  valid program                      |  Unknown/Multiple
      Blocked By:                    |               Test Case:
 Related Tickets:                    |                Blocking:
                                     |  Differential Revisions:
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Comment (by acowley):

 I ran into this with constraints. A
 [http://www.seas.upenn.edu/~acowley/papers/hocl.pdf paper] I submitted to
 Haskell Symposium describes a method of factoring an embedded language
 into various features. In the current state of things, a language that I
 use for writing GPU programs is defined like this:


 {{{#!hs
 type Hocl c repr = (Abstraction c repr,
                     ArrayFeatures c repr,
                     Bitwise c repr,
                     Boolean c repr,
                     Branch c repr,
                     Comp c repr,
                     Cast c repr,
                     Gather c repr,
                     Image c repr,
                     ImageM c repr,
                     Iteration c repr,
                     IterationM c repr,
                     Math c repr,
                     Statements c repr,
                     Swizzle c repr)
 }}}

 I've already done some nesting for `Math` and `ArrayFeatures`, and I can
 do more, so this isn't a deal breaker for me but a matter of convenience.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10451#comment:4>
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