January 2009 - Haskell-Cafe

ANN: Wired 0.2
by Emil Axelsson 27 Jan '09

27 Jan '09

There is now a new release of Wired available: http://hackage.haskell.org/cgi-bin/hackage-scripts/package/Wired The most important news in this release is that it now contains a 45nm cell library, which means that you can use Wired to create and analyze modern VLSI designs[*] today! However... Wired is still in the experimentation phase, but is slowly stabilizing. The current status is further explained in the package text. There's very little documentation (basically only a few examples), so I expect it to be quite hard to use if you haven't seen it before. I hope to improve the documentation in the future. Feel free to mail me questions meanwhile. / Emil [*] Unfortunately, while the 45nm library is "realistic", it's not based on any actual process that can be fabricated. Contact me if you have access to any real cell library and are interested in using it with Wired.

1 0

ANN: filestore 0.1
by Gwern Branwen 26 Jan '09

26 Jan '09

ANN filestore 0.1 We are pleased to announce the first release of a new library, filestore. What is it? filestore provides a uniform, abstract, generic interface for storing versioned files on disk. It allows calling programs to use generic commands to store strings or binary data and perform various queries, such as 'what files are in this repository?' or 'what were the contents of this file at revision XXXXXXX?' or 'give me a diff of this file between revision XXXXXXX and revision YYYYYYY.' Because the interface is abstract, the calling program is insulated from the messy details of the backend (which might be a VCS or a database). What backends are supported? Darcs and Git are fully supported. There are plans for a SQLite backend. What is this good for? Currently it is used by two wikis, Gitit and Orchid. We hope it will see use in other applications as well that need to version data and would like the various advantages of DVCSs (such as easy collaboration, advanced merging, etc.). Where can you get it? Your local cabal-install, Hackage at http://hackage.haskell.org/cgi-bin/hackage-scripts/package/filestore and of course you can do 'darcs get http://johnmacfarlane.net/repos/filestore' for the very latest. filestore was written by John MacFarlane, Gwern Branwen, and Sebastiaan Visser -- gwern

16 22

bug in System.Mem.StableName
by Alberto G. Corona 26 Jan '09

26 Jan '09

Sometimes the StableName library gives different values for the samr function: Sometines gives two alternate values. I checked it in ghc-6.10.1 under windows and in ghc-6.8.2 under Linux: This is an example Prelude> System.Mem.StableName.hashStableName.System.IO.Unsafe.unsafePerformIO $ System.Mem.StableName.makeStableName (*) 15 Prelude> System.Mem.StableName.hashStableName.System.IO.Unsafe.unsafePerformIO $ System.Mem.StableName.makeStableName (*) 14 Prelude> System.Mem.StableName.hashStableName.System.IO.Unsafe.unsafePerformIO $ System.Mem.StableName.makeStableName (*) 15 Prelude> System.Mem.StableName.hashStableName.System.IO.Unsafe.unsafePerformIO $ System.Mem.StableName.makeStableName (*) 14

3 2

Haskell Web Framework
by Felix Martini 26 Jan '09

26 Jan '09

Hi Michael, May i suggest Johan Tibell's web application interface (see http://github.com/tibbe/hyena/tree/master) It is similar to WSGI. Hyena can then be used as an application server and frameworks won't have to create their own servers. Many people have different opinions about web frameworks but a single very robust Haskell server would be an asset for all frameworks. Felix

2 1

MySQL and HDBC?
by Galchin, Vasili 26 Jan '09

26 Jan '09

Hello, "Real World Haskell" seems to say that the abstraction layer HDBC doesn't support MySQL. If so, in what sense doesn't HDBC support MySQL?? Thanks, Vasili

7 10

Haskell Web Framework
by Michael Snoyman 26 Jan '09

26 Jan '09

I'm interested on starting a project with others to create a powerful Haskell web framework in the same league as Rails or Django. I've enumerated (perhaps ad nauseum) my ideas for it in this blog post: http://blog.snoyman.com/2009/01/25/haskell-web-framework/. If people are interested in this, please respond to me either directly or on this mailing list. Just as a quick summary of the post, I would say the most salient points are that the framework should work in a shared hosting environment and should automatically abstract away most of the issues of writing an Ajax web application. It should also leverage the strengths of Haskell, eg type safety and speed. I welcome all comments and critiques as well. Michael

3 3

Re: [Haskell-cafe] mapM_ -> Monoid.Monad.map
by George Pollard 26 Jan '09

26 Jan '09

On Fri, 2009-01-23 at 21:30 +0000, Joachim Breitner wrote: > Hi, > > Am Freitag, den 23.01.2009, 21:50 +0100 schrieb Henning Thielemann: > > However our recent Monoid discussion made me think about mapM_, > > sequence_, and friends. I think they could be useful for many monads if > > they would have the type: > > mapM_ :: (Monoid b) => (a -> m b) -> [a] -> m b > > I expect that the Monoid instance of () would yield the same efficiency > > as todays mapM_ > > will it? This is based on a naive, not well-founded understanding of > haskell evaluation, but looking at > > instance Monoid () where > > mempty = () > > _ `mappend` _ = () > > mconcat _ = () > I’d assume that evaluating > > mapM_ (putStrLn) lotsOfLargeStrings > with your proposed mapM_ will leave a thunk equivalent to > > () `mappend` () `mappend` () `mappend`... > in memory until the mapM_ has completely finished, where each () is > actually an unevalutated thunk that still has a reference to one of the > elements in the lotsOfLargeStrings list. Perhaps this is why the Monoid instance for () in GHC's source has the comment "should this be strict?" :)

18 57

ANN: Hayoo! beta 0.3
by Timo B. Hübel 25 Jan '09

25 Jan '09

Hello! We are pleased to announce the next beta version 0.3 of Hayoo!, the Haskell API search engine with find-as-you-type and suggestions. Visit Hayoo! here: http://holumbus.fh-wedel.de/hayoo Basically, there is one new major feature available: Hayoo! now works even if your browser does not support JavaScript. Of course, this means that you won't have the find-as-you-type functionality, but everything else will be available. Hence everybody who has been scared away from Hayoo! because of all this crazy AJAX stuff now has no excuse anymore for not using Hayoo! ;-) Along the way we fixed several minor bugs and slightly improved the ranking algorithm as well as the help page. Since the last official announcement we were also able to bring back the source links. Still to come in the next weeks is a major index update to reflect the incredible package growth on Hackage. Please let us know about any problems, hints and suggestions. Happy hacking, Timo

1 0

wxHaskell and XP-Themes
by Günther Schmidt 25 Jan '09

25 Jan '09

Hi, my app is using wxHaskell for the gui part, how can I make it use XP-Themes? On XP it's using the Win2k themes. Günther

2 1

how to implement daemon start and stop directives?
by Belka 25 Jan '09

25 Jan '09

Hi! Could somebody please share some experience on how to implement daemon start and stop directives. In theory I need something like this: 1. "my_daemon start" - starts my app with an infinite loop of serving inside. 2. "my_daemon stop" - puts in some TVar a value signalizing, that stop is given - infinite loop brakes. 3. ...it on Linux platform. Thanks in advance! -- View this message in context: http://www.nabble.com/how-to-implement-daemon-start-and-stop-directives--tp… Sent from the Haskell - Haskell-Cafe mailing list archive at Nabble.com.

8 17