RE: constraint deduction bug?

Yes, looks odd. Please do give us a test case. Thank you! S | -----Original Message----- | From: ghc-devs-bounces@haskell.org [mailto:ghc-devs-bounces@haskell.org] | On Behalf Of Dimitrios Vytiniotis | Sent: 22 March 2013 10:01 | To: Richard Eisenberg; Gabor Greif | Cc: ghc-devs@haskell.org | Subject: RE: constraint deduction bug? | | Is Intersect (or some other of the constructors involved, maybe Empty?) | kind-polymorphic and instantiated in the two sites (wanted vs. given) | with different kind variables which end up being unconstrained, or | something like that? Then it might be the case that we don't get a match | (which is rather unintuitive, I | agree) and the constraint is not solved. | | Even if it's a case like this it's probably best to do submit a small | reproducible example and we will have a look. | | Thanks | d- | | | | > -----Original Message----- | > From: ghc-devs-bounces@haskell.org [mailto:ghc-devs- | > bounces@haskell.org] On Behalf Of Richard Eisenberg | > Sent: Friday, March 22, 2013 1:11 AM | > To: Gabor Greif | > Cc: ghc-devs@haskell.org | > Subject: Re: constraint deduction bug? | > | > It certainly looks trivial to me. | > | > Richard | > | > On Mar 21, 2013, at 7:59 PM, Gabor Greif wrote: | > | > > In context of a bigger source file I got this error from GHC (HEAD) | > > | > > Could not deduce (Intersect | > > [KeySegment] (BuriedUnder sub k ('Empty | > > [KeySegment])) inv | > > ~ 'Empty [KeySegment]) | > > from the context (Intersect | > > [KeySegment] (BuriedUnder sub k ('Empty | > > [KeySegment])) inv | > > ~ 'Empty [KeySegment]) | > > bound by a pattern with constructor | > > Nil :: forall (k :: BOX). Sing (Inventory k) ('Empty | k), | > > in a pattern binding in | > > 'do' block | > > | > > Can somebody confirm that this constraint should be trivially | > > deducible from the context? | > > | > > Then I'll try to come up with a reduced repro case. | > > | > > Cheers, | > > | > > Gabor | > > | > > _______________________________________________ | > > ghc-devs mailing list | > > ghc-devs@haskell.org | > > http://www.haskell.org/mailman/listinfo/ghc-devs | > | > | > _______________________________________________ | > ghc-devs mailing list | > ghc-devs@haskell.org | > http://www.haskell.org/mailman/listinfo/ghc-devs | | _______________________________________________ | ghc-devs mailing list | ghc-devs@haskell.org | http://www.haskell.org/mailman/listinfo/ghc-devs