#4226: Lifting constraints is questionably correct for implicit parameters.
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Reporter: dolio | Owner:
Type: bug | Status: new
Priority: normal | Milestone:
Component: Compiler (Type checker) | Version: 6.12.1
Keywords: implicit parameters | Difficulty:
Os: Linux | Testcase:
Architecture: x86_64 (amd64) | Failure: Other
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Changes (by ezyang):
* cc: ezy...@… (added)
Comment:
Some more interesting behavior:
{{{
Prelude> let ?p = 5 in (let ?p = 1 in ((\ () -> ?p + 1) :: (() -> ((?p ::
Int) => Int)))) ()
2
Prelude> let ?p = 5 in (((let ?p = 1 in \ () -> ?p + 1) :: (() -> ((?p ::
Int) => Int)))) ()
6
}}}
As far as I can tell, we need to tell the type-checker about the higher-
rank as close to the desired location as possible in order to see this
behavior.
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/4226#comment:3>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
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