Functional dependencies can return kinds, type families cannot

2014-02-13 Thread José Pedro Magalhães
Hello, Maybe this is well known already (or maybe it's a bug), but lately I've again found that functional dependencies are more versatile than type families. In particular, they can be used to compute kinds from types, whereas type families cannot. Consider the code below, which implements a

Re: [Solaris bindist] ANNOUNCE: GHC 7.8.1 Release Candidate 1

2014-02-13 Thread Christian Maeder
Am 06.02.2014 15:27, schrieb Páli Gábor János: On Thu, Feb 6, 2014 at 1:39 PM, Merijn Verstraaten mer...@inconsistent.nl wrote: On Feb 6, 2014, at 10:33 , Christian Maeder wrote: or (as I've seen elsewhere) better (?) #!/usr/bin/env bash Definitely use this, FreeBSD (for example) does not

[Typeable2] Re: ANNOUNCE: GHC 7.8.1 Release Candidate 1

2014-02-13 Thread Christian Maeder
Hi, with ghc-7.8.20140130 I get the compilation error: Not in scope: type constructor or class ‛Typeable2’ Perhaps you meant ‛Typeable’ (imported from Data.Typeable) What is the recommend way to adjust my code or my dependencies? Cheers Christian Am 03.02.2014 23:35, schrieb Austin

Re: [Typeable2] Re: ANNOUNCE: GHC 7.8.1 Release Candidate 1

2014-02-13 Thread Daniil Frumin
I think that the preferred solution is to get rid of the custom Typeable(2) instances and just derive Typeable On Thu, Feb 13, 2014 at 5:22 PM, Christian Maeder christian.mae...@dfki.de wrote: Hi, with ghc-7.8.20140130 I get the compilation error: Not in scope: type constructor or class

Re: Functional dependencies can return kinds, type families cannot

2014-02-13 Thread Richard Eisenberg
On Feb 13, 2014, at 4:28 AM, José Pedro Magalhães j...@cs.uu.nl wrote: The most interesting part here is the functional dependency fs - k, where k is a kind variable! If this is not a bug (and it does seem to work as I expect it to), then could we have type families return kinds too?...