#1991: Improve GADT type inference
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Reporter: guest | Owner:
Type: feature request | Status: closed
Priority: normal | Milestone:
Component: Compiler (Type checker) | Version: 6.6.1
Severity: normal | Resolution: wontfix
Keywords: | Difficulty: Unknown
Testcase: | Architecture: Unknown
Os: Unknown |
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Changes (by simonpj):
* status: new => closed
* resolution: => wontfix
Comment:
I'm afraid this is never going to compile without a type signature for
`prIO`: in the presence of GADTs we lack principal types. See e.g.
[http://research.microsoft.com/%7Esimonpj/papers/gadt/index.htm Simple
unification-based type inference for GADTs] for more info.
The error message is a bit better in 6.8.
{{{
T1991.hs:11:6:
GADT pattern match in non-rigid context for `NewRef'
}}}
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/1991#comment:1>
GHC <http://www.haskell.org/ghc/>
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