August 2006 - Libraries

RE: Idea to allow people to comment on Haskell docs
by Simon Peyton-Jones 09 Jan '07

09 Jan '07

| I've had a go at patching Haddock to put a link on the page for each | module. It's controlled by an optional --wiki=URL flag. | | As an example, I used this with the (devel version of the) Gtk2Hs docs: | | http://haskell.org/gtk2hs/docs/devel/ | | For example this page: | | http://haskell.org/gtk2hs/docs/devel/Graphics-Rendering-Cairo-SVG.html It looks great! But I'd never have found the link if you hadn't pointed me at it. Rather than "Wiki" say "User comments". And I think the per-entry [User comment] link is essential. Typically people are going to be looking at a particular thing. For example, here http://haskell.org/gtk2hs/docs/devel/Graphics-Rendering-Cairo-SVG.html#v %3AsvgRenderFromString is where I'd look for the link for svgRenderFromString. Does MediaWiki support anchors in the middle of a page? That's essential here -- we want one Wiki page for one Haddock page. On a closely related matter, Benjamin Pierce told me how often he wished that there was a link from the Haddock documentation to the source code for a function. Especially for Prelude functions, he's dead right. So another really useful Haddock enhancement would be the ability to add links to the source code from the Haddock docs --- again on a per-function basis. Do you feel like adding that too? Where should the code live? I'd suggest snap-shoting it at the moment that the Haddock docs are generated, and putting the files with the Haddock docs. Simon

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Success Story: Cabal and Dlls
by Jason Dagit 01 Dec '06

01 Dec '06

Hello, I would like to report that I was able to use Cabal with Visual Haskell to build Dlls in windows. I have posted the details about this on the Haskell wiki (and started an extremely minimal Cabal page). If my content is in the wrong place, please feel free to move it (or edit it or whatever). http://www.haskell.org/haskellwiki/Cabal The trick was to take the final HSfoo-0.1.o file generated by the normal build process (and linked with the DllMain.c code) and tell ghc to build a dll. I use -package with each of the dependencies in the cabal file to link with the needed libraries. The resulting dll seems to be working. This approach is a bit hackish and while I've tried to implement as much of it as I can in a general way it requires you to hack your Setup.lhs file if you want to 1) build static 2) specify your exports 3) specify the name of the resulting dll. Also, it's only been tested on my setup which uses Visual Haskell so it may not be fit for general consumption. Finally, I just started really looking at Cabal yestarday so I may not have considered things which an experienced Cabal user would think about. Is it possible to get this functionality built directly into Cabal so that I tell it I want a DLL built from a library and it knows how to make it happen? Thanks, Jason

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darcs patch: Improve Control.Monad.filterM:
by Spencer Janssen 24 Oct '06

24 Oct '06

Fri Aug 4 13:49:57 CDT 2006 Spencer Janssen <sjanssen(a)cse.unl.edu> * Improve Control.Monad.filterM: * filterM is defined in terms of foldr, making it a good consumer in GHC's fusion framework * filterM uses linear stack space with respect to the number of items that the predicate returns true, rather than the total number of elements in the input.

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Portable keyboard signal handling
by Robert Dockins 04 Sep '06

04 Sep '06

Friends, I have a Haskell library that is currently GHC-only. However, I'm working on making it more portable, with the short-term goal of running on Hugs and the hope of being Haskell' compliant when the time comes. One problem I've run into is that I need a way to portably handle Ctrl-C. On Posix systems, this can be done in a pretty straightforward manner using System.Posix.Signals. However, for win32, I've been relying on the GHC.ConsoleHandler module, which is obviously GHC-specific. Because the module is short, I've attached the complete code text to the end of this message. So, my question is, what should my strategy be? I could snarf the entire contents of GHC.ConsoleHandler into my project (yuck!). I could try to get the ConsoleHandler module out of the GHC walled garden. I could try to get the 'withControlCHandler' function into a future release of the standard libs . Or... What do you think? Have I missed some other option? Rob Dockins Speak softly and drive a Sherman tank. Laugh hard; it's a long way to the bank. -- TMBG module System.Console.Shell.ConsoleHandler ( withControlCHandler ) where import qualified Control.Exception as Ex #ifndef mingw32_HOST_OS import qualified System.Posix.Signals as PS withControlCHandler :: IO () -> IO a -> IO a withControlCHandler hdl m = Ex.bracket (PS.installHandler PS.keyboardSignal (PS.Catch hdl) Nothing) (\oldh -> PS.installHandler PS.keyboardSignal oldh Nothing) (\_ -> m) #else import qualified GHC.ConsoleHandler as CH handleCtrlC :: IO () -> CH.Handler handleCtrlC hdl = CH.Catch $ \ev -> case ev of CH.ControlC -> hdl _ -> return () withControlCHandler :: IO () -> IO a -> IO a withControlCHandler hdl m = Ex.bracket (CH.installHandler (handleCtrlC hdl)) (\oldh -> CH.installHandler oldh) (\_ -> m) #endif

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darcs patch: New function isInfixOf that searches a list for a give...
by John Goerzen 01 Sep '06

01 Sep '06

Thu Aug 31 10:15:56 CDT 2006 John Goerzen <jgoerzen(a)complete.org> * New function isInfixOf that searches a list for a given sublist Example: isInfixOf "Haskell" "I really like Haskell." -> True isInfixOf "Ial" "I really like Haskell." -> False This function was first implemented in MissingH as MissingH.List.contains

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System.Posix.User is inadequate
by John Goerzen 31 Aug '06

31 Aug '06

There are several problems with this module: 1) There is no way to get all users/groups on the system (getpwent) 2) The UserEntry type does not reflect the Gecos field (pw_gecos) 3) The UserEntry type does not reflect the password field (pw_passwd) 4) The GroupEntry type does not reflect the gr_passwd field This renders is unfortunately useless for some very basic Unix tasks. Is there still time to fix this for 6.6?

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darcs patch: Derive Show, Read, and Eq for UserEntry and GroupEntry
by John Goerzen 31 Aug '06

31 Aug '06

Thu Aug 31 09:50:22 CDT 2006 John Goerzen <jgoerzen(a)complete.org> * Derive Show, Read, and Eq for UserEntry and GroupEntry

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darcs patch: Added support for getpwent/getgrent (and 1 more)
by John Goerzen 31 Aug '06

31 Aug '06

Wed Aug 30 08:25:50 CDT 2006 John Goerzen <jgoerzen(a)complete.org> * Added support for getpwent/getgrent Wed Aug 30 08:45:17 CDT 2006 John Goerzen <jgoerzen(a)complete.org> * Fix compilation issues with new getgrent/getpwent code

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System.Posix.Signals
by Neil Mitchell 30 Aug '06

30 Aug '06

Hi, Why is System.Posix.Signals defined in base on Windows, but entirely blank, while System.Posix.Process is defined in Unix? If this is a dependancy issue, then shouldn't System.Posix.Internals.Signals be in the base, and then unix export System.Posix.Signals, which is just a reexport of this? This issue is annoying because I'm trying to at least write null stubs for the functions so I can compile a program requiring unix on Windows. It doesn't help that Windows ships a version of Signals with an entirely different interface... Thanks Neil

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darcs patch: Added pw_passwd and pw_gecos fields to U... (and 3 more)
by jgoerzen＠complete.org 29 Aug '06

29 Aug '06

Tue Aug 29 13:50:51 CDT 2006 John Goerzen <jgoerzen(a)complete.org> * Added pw_passwd and pw_gecos fields to UserEntry structure System.Posix.User was missing pw_gecos and pw_passwd in UserEntry. I have added them, so now the full struct passwd is represented. Tue Aug 29 13:53:00 CDT 2006 John Goerzen <jgoerzen(a)complete.org> * Whitespace changes for better alignment in unpackUserEntry Tue Aug 29 13:55:36 CDT 2006 John Goerzen <jgoerzen(a)complete.org> * Add missing field gr_passwd to GroupEntry Tue Aug 29 13:59:32 CDT 2006 John Goerzen <jgoerzen(a)complete.org> * Added some Haddock docs for UserEntry and GroupEntry

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