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Equality Constraints (a ~ b)

glasgow-user - Mon, 01/12/2015 - 1:04am
Hi, I am trying to find more background on these. They don’t exist in the Haskell 2010 Language Report, they didn’t exist in ghc 6.8.2 but make an appearance in 7.0.1. The documentation in the manual is rather sparse and doesn’t contain a reference: https://downloads.haskell.org/~ghc/latest/docs/users_guide.pdf section 7.11. Folk on #ghc referred me to http://research.microsoft.com/en-us/um/people/simonpj/papers/ext-f/. I can find papers that refer to ~ in F_C (aka FC?) but as far as I can tell not in the Haskell language itself. Many thanks Dominic Steinitz dominic< at >steinitz.org http://idontgetoutmuch.wordpress.com
Categories: Offsite Discussion

FLTK bindings near completion. Need communityassistance ...

haskell-cafe - Sun, 01/11/2015 - 8:39pm
Hi all, I've been working on bindings [1] to the FLTK GUI toolkit [2] and I've come to the point where it's mostly complete but I could use some help from the community before I put it up on Hackage. My hope is to eventually fill the need in the Haskell ecosystem for a native GUI library that: - runs on all platforms - is easily installable - is small and fast - has a minimum of dependencies. Currently this library uses only base, stm, bytestring and c2hs. - is conservative with extensions. Currently the most recent extension required is GADTs. If any of this sounds good to you, I could use some help with: - testing the build on Linux and OSX. This should be as simple as installing FLTK, cloning the repo [1] and running `cabal build`. Better instructions are in included README. - getting it to build on Windows. I unfortunately don't have access to a Windows machine. - getting it to build on older GHC's. I used 7.8.3 because that is what I have, but it should work back to the first version of GHC that intro
Categories: Offsite Discussion

Cabal: Specify multiple package databases in config file

libraries list - Sun, 01/11/2015 - 2:36am
Hi All, Is it possible to specify multiple package databases in Cabal's config file? Currently, I have two installed package databases. One is the system readonly package database, and the other is the system writable package database. This structure is due to how packaging works on Haiku, so can't be changed. A similar structure would also exist for user package databases. My Cabal config file currently looks like: package-db: /packages/ghc/.self/lib/package.conf.d I need this to be something like: package-db: /packages/ghc/.self/lib/package.conf.d; /system/non-packaged/lib/ghc/package.conf.d Is this possible with the Cabal config file? If so, what is the correct syntax to use? Many Thanks, Jessica
Categories: Offsite Discussion

System.Posix.IO.ByteString

libraries list - Sun, 01/11/2015 - 2:15am
Hi All, I'm playing around with some low level IO and found the following function: System.Posix.IO.fdRead :: Fd -> ByteCount -> IO (String, ByteCount) Ok, close, but what if I need a ByteString instead. I then found this: System.Posix.IO.ByteString.fdRead :: Fd -> ByteCount -> IO (String, ByteCount) which is identical to the one above. The ByteString in the module name suggests it would be using ByteString instead of String? Can anyone explain this for me? Cheers, Erik
Categories: Offsite Discussion

New gtk2hs 0.12.4 release

gtk2hs - Wed, 11/21/2012 - 12:56pm

Thanks to John Lato and Duncan Coutts for the latest bugfix release! The latest packages should be buildable on GHC 7.6, and the cairo package should behave a bit nicer in ghci on Windows. Thanks to all!

~d

Categories: Incoming News