Re: [GHC] #13920: 自動選擇實例

[GHC]

#13920: 自動選擇實例
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        Reporter:  zaoqi             |                Owner:  (none)
            Type:  feature request   |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.0.2
      Resolution:                    |             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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Comment (by zaoqi):

 Replying to [comment:2 bgamari]:
 > I spent a few minutes looking at this: It seems like you want `(u 'c')
 :: U [Int,Char]` to behave like `t1 (uone 'c') :: U [Int,Char]`, but they
 are quite different.
 >
 > Can you provide some more description of the problem? What does GHC do
 and how does this differ from what you would want it to do?

 {{{#!hs
 (t1 . t1 . t1 . t1 . t1 . t1 . t1) :: a -> a -- t1 = id
 t1 :: U '[Char] -> U [Int, Char] -- t1 = USucc
 t :: U '[Char] -> U [Int, Char]
 t (uone 'c') :: U [Int,Char]
 (u 'c') :: U [Int,Char]
 }}}

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13920#comment:3>
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