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Haskell Users in the West Michigan Area?
by John Van Enk 11 Feb '09

11 Feb '09

I'm wondering if there are people in the West Michigan, USA area who'd be interested in forming WMHUG (West Michigan Haskell Users Group). Any one on here from that area? /jve

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DPH Prelude
by James Swaine 11 Feb '09

11 Feb '09

I was wondering if anyone could point me to a more in-depth explanation of why we are (currently) restricted to using a special-purpose standard Prelude when writing vectorised code with DPH. We're prototyping using several data-parallel languages for a research project here at Northwestern University, and wanted to get a better idea how we might go about adding vectorisation support for addtional types/operations. There are certain simple operations which don't appear to be supported for primitive types yet (e.g. the ^ and ** operators for an Int type). These are the kinds of things we'd like to look into as a first step. Much thanks, James Swaine

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GHC development
by Andrew Coppin 11 Feb '09

11 Feb '09

OK, so I have a small question. I was just wondering what the current state of development with GHC is. So, I had a look at the developer wiki. Unfortunately, as best as I can tell, most of the status pages haven't been updated in many months. (Most of them still talk about what will or won't be in 6.10.1, which has been *released* for a while now.) What's the best way to find out what the "real" state of affairs is? What are the developers really working on? What's on hold? How far have people got with things? Etc. (Yes, I know. I'm nosey...)

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How outdated is Hugs?
by Rafael Gustavo da Cunha Pereira Pinto 11 Feb '09

11 Feb '09

Hi, I see Hugs last source code snapshot dates back to 2006. Was there any updates? Regards -- Rafael Gustavo da Cunha Pereira Pinto Electronic Engineer, MSc.

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Re: [Gtk2hs-users] Gtk2HS 0.10.0 Released
by Peter Verswyvelen 11 Feb '09

11 Feb '09

Nice. The demos are now included only in the source distri right? On Wed, Feb 11, 2009 at 1:40 PM, Axel Simon <Axel.Simon(a)ens.fr> wrote: > On Wed, 2009-02-11 at 13:36 +0100, Peter Verswyvelen wrote: > > Great job! I have been using the RC1 version for a while and it works > > well. > > > > > > - Full switch to the new model-view implementation using a Haskell > > model > > > > > > This is very interesting. Do demos exist to show this? > > > > Yes, all the demos under demo/treeList have been converted to use the > new ModelView (the directory name is stale, it should probably be > renamed to modelView since TreeList was the old interface). > > There's also a combo box demo in demo/menu. > > Cheers, > Axel. > > > On Wed, Feb 11, 2009 at 5:32 AM, Peter Gavin <pgavin(a)gmail.com> wrote: > > Hi everyone, > > > > I'd like to release the announcement of Gtk2HS 0.10.0. A lot > > of new > > stuff has gone into this release, including: > > > > - Support for GHC 6.10 > > - Bindings to GIO and GtkSourceView-2.0 > > - Full switch to the new model-view implementation using a > > Haskell model > > - Support for many more model-based widgets such as IconView > > and an > > updated binding for ComboBox > > - Full Drag-and-Drop support > > - Better support for Attributes in Pango > > - Replaced Event for EventM monad, thereby improving > > efficiency and > > convenience > > - Functions for interaction between Cairo and Pixbuf drawing > > - Lots of bug fixes, code cleanups, and portability > > improvements > > > > With this release, the bindings to GnomeVFS and > > GtkSourceView-1.0 have > > been deprecated. The TreeList modules have been deprecated > > from the > > Gtk+ bindings. > > > > Source and Win32 binaries are available at: > > > > > > > https://sourceforge.net/project/showfiles.php?group_id=49207&package_id=424… > > > > Thanks to everyone who submitted bug fixes and features this > > time around! > > > > Thanks, > > Peter Gavin > > Gtk2HS Release Manager > > > > > > > ------------------------------------------------------------------------------ > > Create and Deploy Rich Internet Apps outside the browser with > > Adobe(R)AIR(TM) > > software. With Adobe AIR, Ajax developers can use existing > > skills and code to > > build responsive, highly engaging applications that combine > > the power of local > > resources and data with the reach of the web. Download the > > Adobe AIR SDK and > > Ajax docs to start building applications > > today-http://p.sf.net/sfu/adobe-com > > _______________________________________________ > > Gtk2hs-users mailing list > > Gtk2hs-users(a)lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/gtk2hs-users > > > > > > > ------------------------------------------------------------------------------ > > Create and Deploy Rich Internet Apps outside the browser with > Adobe(R)AIR(TM) > > software. With Adobe AIR, Ajax developers can use existing skills and > code to > > build responsive, highly engaging applications that combine the power of > local > > resources and data with the reach of the web. Download the Adobe AIR SDK > and > > Ajax docs to start building applications today- > http://p.sf.net/sfu/adobe-com > > _______________________________________________ Gtk2hs-users mailing list > Gtk2hs-users(a)lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/gtk2hs-users > >

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Re: [Gtk2hs-users] Gtk2HS 0.10.0 Released
by Peter Verswyvelen 11 Feb '09

11 Feb '09

Great job! I have been using the RC1 version for a while and it works well. - Full switch to the new model-view implementation using a Haskell model This is very interesting. Do demos exist to show this? On Wed, Feb 11, 2009 at 5:32 AM, Peter Gavin <pgavin(a)gmail.com> wrote: > Hi everyone, > > I'd like to release the announcement of Gtk2HS 0.10.0. A lot of new > stuff has gone into this release, including: > > - Support for GHC 6.10 > - Bindings to GIO and GtkSourceView-2.0 > - Full switch to the new model-view implementation using a Haskell model > - Support for many more model-based widgets such as IconView and an > updated binding for ComboBox > - Full Drag-and-Drop support > - Better support for Attributes in Pango > - Replaced Event for EventM monad, thereby improving efficiency and > convenience > - Functions for interaction between Cairo and Pixbuf drawing > - Lots of bug fixes, code cleanups, and portability improvements > > With this release, the bindings to GnomeVFS and GtkSourceView-1.0 have > been deprecated. The TreeList modules have been deprecated from the > Gtk+ bindings. > > Source and Win32 binaries are available at: > > > > https://sourceforge.net/project/showfiles.php?group_id=49207&package_id=424… > > Thanks to everyone who submitted bug fixes and features this time around! > > Thanks, > Peter Gavin > Gtk2HS Release Manager > > > > ------------------------------------------------------------------------------ > Create and Deploy Rich Internet Apps outside the browser with > Adobe(R)AIR(TM) > software. With Adobe AIR, Ajax developers can use existing skills and code > to > build responsive, highly engaging applications that combine the power of > local > resources and data with the reach of the web. Download the Adobe AIR SDK > and > Ajax docs to start building applications today- > http://p.sf.net/sfu/adobe-com > _______________________________________________ > Gtk2hs-users mailing list > Gtk2hs-users(a)lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/gtk2hs-users >

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ANN: Data.Stream 0.3
by Wouter Swierstra 11 Feb '09

11 Feb '09

I've released a new version of the Data.Stream package, a modest library for manipulating infinite lists. Changes include: * Support for lazy SmallCheck; * Improved Show instance; * Stricter scans; * Various documentation fixes; * Several new functions from Data.List. Many of these features were based on patches by Bas van Dijk - thank you Bas! Haddock: http://www.cs.nott.ac.uk/~wss/repos/Stream/dist/doc/html/Stream/ Hackage: http://hackage.haskell.org/cgi-bin/hackage-scripts/package/Stream/ darcs: darcs get http://www.cs.nott.ac.uk/~wss/repos/Stream All the best, Wouter

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Re: [Haskell-cafe] evaluation semantics of bind
by Alberto G. Corona 11 Feb '09

11 Feb '09

forwarded: Yes! if no state is passed, the optimization makes sense and the term is not executed, like any lazy evaluation. For example, I used the debugger (that is, without optimizations) to verify it with the Maybe monad: op x= x+x print $ Just (op 1) >>= \y-> return (Just 2) does not evaluate op 1 but print $ Just (op 1) >>= \y-> return y does execute it. The trace of the first: [1 of 1] Compiling Main ( test.hs, interpreted ) Ok, modules loaded: Main. *Main> :set stop :list *Main> :step main Stopped at test.hs:4:6-43 _result :: IO () = _ 3 4 main= print $ Just (op 1) >>= \y-> return 2 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 5 [test.hs:4:6-43] *Main> :step Stopped at test.hs:4:14-43 _result :: Maybe Integer = _ 3 4 main= print $ Just (op 1) >>= \y-> return 2 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 5 [test.hs:4:14-43] *Main> :step Stopped at test.hs:4:14-24 _result :: Maybe Integer = _ 3 4 main= print $ Just (op 1) >>= \y-> return 2 ^^^^^^^^^^^ 5 [test.hs:4:14-24] *Main> :step Stopped at test.hs:4:35-43 _result :: Maybe Integer = _ 3 4 main= print $ Just (op 1) >>= \y-> return 2 ^^^^^^^^^ 5 [test.hs:4:35-43] *Main> :step Just 2 But in the second case op is executed: *Main> :step main Stopped at test.hs:4:6-43 _result :: IO () = _ 3 4 main= print $ Just (op 1) >>= \y-> return y ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 5 [test.hs:4:6-43] *Main> :step Stopped at test.hs:4:14-43 _result :: Maybe Integer = _ 3 4 main= print $ Just (op 1) >>= \y-> return y ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 5 [test.hs:4:14-43] *Main> :step Stopped at test.hs:4:14-24 _result :: Maybe Integer = _ 3 4 main= print $ Just (op 1) >>= \y-> return y ^^^^^^^^^^^ 5 [test.hs:4:14-24] *Main> :step Stopped at test.hs:4:35-43 _result :: Maybe Integer = _ y :: Integer = _ 3 4 main= print $ Just (op 1) >>= \y-> return y ^^^^^^^^^ 5 [test.hs:4:35-43] *Main> :step Just Stopped at test.hs:4:20-23 _result :: Integer = _ 3 4 main= print $ Just (op 1) >>= \y-> return y ^^^^ 5 [test.hs:4:20-23] *Main> :step Stopped at test.hs:6:0-8 _result :: Integer = _ 5 6 op x= x+x ^^^^^^^^^ 7 [test.hs:6:0-8] *Main> :step Stopped at test.hs:6:6-8 _result :: Integer = _ x :: Integer = _ 5 6 op x= x+x ^^^ 7 [test.hs:6:6-8] *Main> :step Just 2 2009/2/5 Gregg Reynolds <dev(a)mobileink.com>- Ocultar texto citado - > > On Thu, Feb 5, 2009 at 9:27 AM, Bulat Ziganshin <bulat.ziganshin(a)gmail.com> wrote: >> >> Hello Gregg, >> >> Thursday, February 5, 2009, 6:20:06 PM, you wrote: >> >> > An optimizer can see that the result of the first getChar is >> > discarded and replace the entire expression with one getChar without >> > changing the formal semantics. >> >> this is prohibited by using pseudo-value of type RealWorld which is >> passed through entire action stream. actually, order of execution is >> controlled by dependencies on this values >> >> http://haskell.org/haskellwiki/IO_inside >> > Thanks. I actually read that a few weeks ago and forgot all about it. So the gist is that type IO has special magic semantics. Formal, but hidden. Which means monad semantics are built in to the language, at least for that type. The Haskell Report doesn't seem to say anything about this, which seems odd. > > But then for non-IO monads, the optimization would be allowed, no? Of course; only the IO monad has external world behavior. > > Thanks, > > gregg > > _______________________________________________ > Haskell-Cafe mailing list > Haskell-Cafe(a)haskell.org > http://www.haskell.org/mailman/listinfo/haskell-cafe >

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Why does sleep not work?
by John Ky 11 Feb '09

11 Feb '09

Hi Haskell Cafe, I wrote very short program to sleep for 5 seconds compiled with the -threaded option in ghc on the Mac OS X 1.5. I am finding that using the sleep function doesn't sleep at all, whereas using threadDelay does: main = do putStrLn "Waiting for 5 seconds." threadDelay 5000000 -- works putStrLn "Done." main = do putStrLn "Waiting for 5 seconds." sleep 5 -- doesn't sleep at all putStrLn "Done." Anybody know what's happening? Thanks -John

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Painting logs to get a coloured tree
by Joachim Breitner 11 Feb '09

11 Feb '09

Hi, I have a problem that, it seems, I can not solve cleanly without resorting to imperative programming (via ST): Assume you have a tree (and you can think of a real tree here), defined by something like this: data Tree a = Bud | Branch a Double Tree Tree -- | ` Lenght of this branch -- ` General storage field for additional information Now, I have a nice algorithm that calulates something for each branch, but it only works on lists of branches, so I have to cut them apart first, remembering their position in space, and then work on these, well, logs. data Point = Point Double Double data Log = Log Point Point type Info = ... noInfo :: Info cutTreeApart :: Tree a -> [(Log, a)] someAlgorithm :: [(Log,a)] -> [(a, Info)] Conveniently, the algorithm allows me to tag the logs with something, to be able to keep track at least somewhat of the logs. Unfortunately, I need this information in the storage field in my Tree, as the list of logs is not sufficient for later calculations. Idea: Using ST ============== annotateTree :: Tree a -> Tree Info annotateTree tree = runSt $ do -- Put an STRef in each node treeWithPointer <- mapM const (newSTRef noInfo) tree -- Cut this tree apart let logsWithPointers = cutTreeApart treeWithPointer -- Run the algorithm let informations = someAlgorithm logsWithPointers -- Put the information back, via the ST ref mapM (\(stRef, info) -> writeSTRef stRef info) informations -- Read the ST refs mapM readIORef tree Note that I assume a instance Traversable Tree here, and mapM is Data.Traversable.mapM. Now while this works, and while ST is still somewhat pure, I’m wondering if there is no better way of expressing "This piece of information came from the point in a data structure, so something else can be put here easily". Some ideas where numbering the Nodes and then using this number as the tag on the log, but this is not much different from using STRefs, it seems. Thanks, Joachim -- Joachim "nomeata" Breitner mail: mail(a)joachim-breitner.de | ICQ# 74513189 | GPG-Key: 4743206C JID: nomeata(a)joachim-breitner.de | http://www.joachim-breitner.de/ Debian Developer: nomeata(a)debian.org

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