#2855: Surprising type (family) type derived
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Reporter: guest | Owner:
Type: feature request | Status: new
Priority: normal | Milestone:
Component: Compiler | Version: 6.10.1
Severity: normal | Resolution:
Keywords: | Difficulty: Unknown
Testcase: | Os: Unknown/Multiple
Architecture: Unknown/Multiple |
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Comment (by guest):
So what about my attached last example? It's another one of these the
type that ghc reports cannot be inserted in the code. Very frustrating.
You say "At what type should we call the poymorphic function x?" Well, I
want it to be the x from the dictionary (C a) that I'm passing. So there
is no doubt at what type it should be called, it's at type (U a). I guess
there's no way to express that.
This is very annoying, because it means that the associated types simply
don't work for some of the tasks that I thought they were supposed to
solve.
I can provide a real life example if that helps.
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/2855#comment:3>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
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