#1353: GHCi hangs when type checking
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Reporter: [EMAIL PROTECTED] | Owner:
Type: bug | Status: closed
Priority: normal | Milestone:
Component: GHCi | Version: 6.6
Severity: normal | Resolution: invalid
Keywords: | Difficulty: Unknown
Os: Linux | Testcase:
Architecture: x86 |
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Changes (by simonpj):
* resolution: => invalid
* status: new => closed
Comment:
You are using `-fallow-undecidable-instances`, and that flag means that
'''you''' are taking responsibility for making sure that type inference
doesn't get into a loop. Maybe the flag should be `-fif-type-inference-
loops-its-my-fault`.
Sure enough, it does. I traced it far enough to see that there was a
cycle in which some improvement happens, and then some context reduction,
and then more improvement. It's not impossible that there's a bug in GHC,
but I didn't look further.
Admittedly, the manual does not specify just '''what''' your proof
obligations are if you use `-fallow-undecidable-instances`. The best
place to start is our paper [http://research.microsoft.com/~simonpj/papers
/fd-chr "Understanding functional dependencies using CHRs"].
So I'm closing this one as 'invalid'.
Simon
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/1353>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
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