October 2003 - Haskell

Re: Question abt num
by Pratik Bhadra 23 Oct '03

23 Oct '03

Thanks, Artie and thanks to Dr Richards! I figured it out. I was not correlating the Exprs properly. Now that I broke it up into Lit1 and Lit2 and am returning a Lit1 or a Lit2 which will return an Expr, it works! :) Pratik -------------------------------- Pratik Bhadra Undergraduate Section Leader The University of Texas at Austin College of Natural Sciences Junior BS Computer Sciences ---------------------------------

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Graduate Student
by htrego＠lancasterlabs.com 22 Oct '03

22 Oct '03

I am a graduate student who is interested in Haskell. I wanted to take a look at the Haskell Wish List but I get the error Warning: MySQL Connection Failed: Can't connect to MySQL server on 'marutea.pms.informatik.uni-muenchen.de' (113) in /usr/local/apache/pms/htdocs/forschung/haskell-wish-list/items.php3 on line 5 Is there anyone who has a copy of the Wish List? Holly Trego Senior Computer Specialist CONFIDENTIAL MATERIAL: This message is intended only for the use of the individual or entity to which it is addressed and may contain information that is privileged, confidential, and exempt from disclosure under applicable law. If received in error, please notify sender by return e-mail and destroy all copies of the original transmission and any attachments. Thank you. If you wish to view information about Lancaster Laboratories, Inc., please visit our website at www.lancasterlabs.com

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RE: Graduate Student
by Simon Peyton-Jones 22 Oct '03

22 Oct '03

So far as GHC is concerned, we're now keeping our "wish list" in SourceForge ,under "Tasks" http://sourceforge.net/pm/?group_id=8032 We've not been very assiduous in maintaining these lists, though. If more people used them, we might be more so. Did you have anything in mind? What sort of project are you looking for? Simon | -----Original Message----- | From: haskell-bounces(a)haskell.org [mailto:haskell-bounces@haskell.org] On Behalf Of | htrego(a)lancasterlabs.com | Sent: 20 October 2003 18:50 | To: haskell(a)haskell.org | Subject: Graduate Student | | I am a graduate student who is interested in Haskell. I wanted to take a | look at the Haskell Wish List but I get the error | | Warning: MySQL Connection Failed: Can't connect to MySQL server on | 'marutea.pms.informatik.uni-muenchen.de' (113) in | /usr/local/apache/pms/htdocs/forschung/haskell-wish-list/items.php3 on line | 5 | | Is there anyone who has a copy of the Wish List? | | Holly Trego | Senior Computer Specialist | | | | CONFIDENTIAL MATERIAL: This message is intended only for the use of the | individual or entity to which it is addressed and may contain information | that is privileged, confidential, and exempt from disclosure under | applicable law. If received in error, please notify sender by return e-mail | and destroy all copies of the original transmission and any attachments. | Thank you. If you wish to view information about Lancaster Laboratories, | Inc., please visit our website at www.lancasterlabs.com | _______________________________________________ | Haskell mailing list | Haskell(a)haskell.org | http://www.haskell.org/mailman/listinfo/haskell

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ANNOUNCE: HToolkit 1.2 released
by Krasimir Angelov 21 Oct '03

21 Oct '03

Dear Haskellers, I am pleased to announce HToolkit 1.2 for Haskell. The HToolkit is a platform independent package for Graphical User Interface. The package is split into two libraries GIO and Port. The Port is a low-level Haskell 98+FFI compatible API, while GIO is a high-level user friendly interface to Port. The current release supports all Windows based platforms and Linux/Unix platforms with GTK/GNOME toolkit. There are many new features and many bugfixes. The 1.2 release is a source incompatible with 1.0 release. Home page ~~~~~~~~~ http://htoolkit.sourceforge.net Incompatible changes: ~~~~~~~~~~~~~~~~~~~~~ 1. There is a new API for creating: - radio menu items (MenuRadioItem) - check boxes (CheckBox) - radio buttons (RadioBox) In the new API each widget is created idependently from the other widgets and after that they are linked together to form a group of related items. 2. The 'drawInWidget' function is renamed to 'paintIn' and the 'drawInBitmap' is renamed to 'paintInBitmap'. 3. The 'dialogFont' function is removed. Both windows and dialogs now use the same font (returned from the 'defaultFont' function). 4. The 'defaultFont', 'defaultFontDef', 'dialogColor', 'windowColor' and 'textColor' functions now return values which are system dependent. The returned values are given from the current theme selected in Windows/GNOME. 5. The 'itemCount' attribute of Menu is removed. There is a new 'count' attribute which is defined in the type class and instances are defined for Popup, ListBox, Notebook, Menu and ToolBar types. 6. The 'visible' attribute of Entry is renamed to 'password'. 7. The windows and the dialogs are created invisible by default and can be shown with the 'showWindow' or 'runDialog' (for dialogs) functions. New features ~~~~~~~~~~~~ 1. The implementation for the ToolBar is completed. Unfortunatelly in this release the toolbars for Linux don't work. The reason is that the CVS version of Port uses GTK 2.3. 2. Each window and dialog can be shown/hidden with the 'showWindow' and 'hideWindow' functions or by changing the value of the new attribute 'visible'. The attribute is read/write and its current value determines whether the window is visible. The windows and the dialogs are created invisible by default and can be shown with the 'showWindow' or 'runDialog' (for dialogs) functions. 4. In HToolkit 1.0 when the dialog size becomes smaller than the minimal size required to layout the controls, the dialog automatically shows scrollers. In HToolkit 1.2 the dialogs cannot be shrinked to a size smaller than the minimal. Under Windows a size gripper is drawn at the righthand bottom corner of the resizable dialogs just like the modern resizable dialogs under Windows. 5. The controls are created invisible by default and are shown only if they are included in the layout expression of their parent. In this way it is possible to dynamically hide/show and rearrange the controls. 6.Three new controls are added: Notebook, GroupBox and CompoundControl. The CompoundControl is a container for other controls with automatic scrollbars. The control supports 'mouse', 'keyboard' and 'paint' events just like the toplevel windows and dialogs. The primary purpose of CompoundControl is to create new custom controls. 7. The layout algorithm is extended with 'stretch', 'hstretch' and 'vstretch' functions in addition to 'fill', 'hfill' and 'vfill'. The new functions stretch only the specified control to fit the entire space without affecting the rest controls in the table. Cheers, Krasimir __________________________________ Do you Yahoo!? The New Yahoo! Shopping - with improved product search http://shopping.yahoo.com

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Re: Calling an external command from a Haskell program
by C.Reinke 21 Oct '03

21 Oct '03

> The function system works fine in Hugs except on windows where DOS limitations > cause the function to always return ExitSuccess. (ghc suffers from the same > problem on Windows.) Actually, that is not quite correct: ghc seems to suffer from this problem only on older Windows versions (such as Windows 98), whereas Hugs seems to have the bug also on newer Windows versions (such as XP), at least in its current binary release.. I reported the ghc/win98 problem earlier, below is what happens on Windows XP. So the bug seems even worse in Hugs than in GHC? Claus PS. why the differences in default access to standard modules? should GHC be more restrictive there? --------------------------------------------------- ___ ___ _ / _ \ /\ /\/ __(_) / /_\// /_/ / / | | GHC Interactive, version 6.0.1, for Haskell 98. / /_\\/ __ / /___| | http://www.haskell.org/ghc/ \____/\/ /_/\____/|_| Type :? for help. Loading package base ... linking ... done. Prelude> System.system "fail" >>= print 'fail' is not recognized as an internal or external command, operable program or batch file. ExitFailure 1 Prelude> --------------------------------------------------- || || || || || || ||__ Hugs 98: Based on the Haskell 98 standard ||___|| ||__|| ||__|| __|| Copyright (c) 1994-2002 ||---|| ___|| World Wide Web: http://haskell.org/hugs || || Report bugs to: hugs-bugs(a)haskell.org || || Version: Nov 2002 _________________________________________ Haskell 98 mode: Restart with command line option -98 to enable extensions Reading file "C:\Program Files\Hugs98\lib\Prelude.hs": Hugs session for: C:\Program Files\Hugs98\lib\Prelude.hs Type :? for help Prelude> :a System Reading file "C:\Program Files\Hugs98\lib\System.hs": Hugs session for: C:\Program Files\Hugs98\lib\Prelude.hs C:\Program Files\Hugs98\lib\System.hs System> system "fail" >>= print 'fail' is not recognized as an internal or external command, operable program or batch file. ExitSuccess

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RE: About Haskell Thread Model
by Simon Marlow 21 Oct '03

21 Oct '03

> On Mon, Oct 13, 2003 at 11:13:56AM +0200, Wolfgang Thaller wrote: > > The reason why we currently do not take advantage of SMP is > that the > > Haskell Heap is a shared data structure which is modified > whenever a > > thunk (an unevaluated expression) is evaluated. Using > synchronisation > > primitives like pthread_mutex_lock for every evaluation of a thunk > > would be deadly for performance. > > There is some old (1999) code in the GHC RTS that attempts > this (using > > intel cmpxchg instructions for synchronisation), but it's currently > > "bitrotted" and I don't know how successful it was. > > cmpxchg and then taking a blocking lock sounds like the 2-tier locking > supported with Linux' new futex system calls. I wonder how they chose > to block in the older GHC RTS. It was a spinlock. There was also an attempt to avoid having to lock every thunk entry and update by partitioning the allocation area per-thread, taking advantage of the fact that most thunk entries and updates are to objects created recently by the current thread. This is about where the experiment stalled - it was interesting, but even if the heap partitioning turned out to be effective, the gains weren't really going to be there without tackling multithreaded GC too (as Jan-Willem already pointed out). Cheers, Simon

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Re: Calling an external command from a Haskell program
by C.Reinke 21 Oct '03

21 Oct '03

> If you want access to its I/O streams as well, you can use > Posix.popen, which is not standard Haskell 98, I think, but it's > in GHC. Even worse, it is not portable (AFAICT)! I'm worried by the tendency towards Posix, at a time when, e.g., GHC by default no longer supports this on Windows (went missing in the move from cygwin to mingw). Some also thought Posix overkill, and wanted a portable replacement for the most-commonly-wanted functionality subset.. Could someone in the know please summarise the state of Posix-support in Haskell implementations in general? I've cc-ed to the libraries list - perhaps someone there could comment on the state of portable replacements for Posix functionality, especially for popen and friends? I seem to recall a very promising discussion about portable and flexible ways to start subprocesses a while ago - has that led to any concrete libraries? Cheers, Claus

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Calling an external command from a Haskell program
by Salvador Lucas 21 Oct '03

21 Oct '03

Dear all, I think this question is not new, but I am not able to find the answer. How to proceed to execute an external Linux command (e.g., 'ls') from a Haskell program? Thanks in advance, Salvador.

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Call for Contributions - HC&A Report (November 2003 edition)
by C.Reinke 20 Oct '03

20 Oct '03

Dear Haskellers, once again, we set out to get an overview of what is going on in all things Haskell, and *you* are invited to help with this effort! Please contribute to the forthcoming fifth edition of our ================================================================ Haskell Communities & Activities Report http://www.haskell.org/communities/ Submission deadline: 31 October 2003 (please send your contributions to me, in plain-ASCII or LaTeX format, keeping "HC&A Report" in the subject line) ================================================================ The Haskell Communities & Activities Reports are a bi-annual, birds-eye overview of Haskell development over the last 6 months, and perhaps an outlook over concrete plans for the next 6 months. If you have only recently joined the Haskell world, have a look through the May 2003 edition - it provides a useful overview, starting points and links that may answer many a FAQ. The current plan is to get contributions in by the end of October, and to get the collective report out early next month (you will find this an excellent opportunity to update your webpages, get out pending releases, announce new projects, summarize recent developments in sub-communities for all Haskellers, etc. ;-). The general idea is to update all existing summaries (these reports are really about *recent/current* activities), to drop any topics that haven't had any activity for two consecutive 6-month periods, and to add any new developments or topics for which no-one contributed summaries to the previous edition, while trying to keep the whole from blowing up (last time, we ended up with about 30 pages). Looking forward to your contributions, Claus (current editor) -- Haskell Communities and Activities Report (November 2003 edition) All contributions are due in by the end of October 2003! http://www.haskell.org/communities/ --------------------------------- topics New suggestions for current hot topics, activities, projects, .. are welcome - especially with names and addresses of potential contacts, but here is a non-exclusive list of likely topics (see also http://www.haskell.org/communities/topics.html ): General Haskell developments; Haskell implementations; Haskell extensions; Standardization and documentation; Haskell tutorials, how-tos and wikis; Organisation of Haskell tool and library development; Haskell-related projects and publications; new research, fancy tools, lonq-awaited libraries, cool applications; Feedback from specialist mailing lists to the Haskell community as a whole; Haskell announcements; .. all (recent) things Haskell Announcements: if you've announced anything new on the Haskell list over the last six months, you'll want to make sure that is reflected in this edition! Project pings: if you're maintaining a Haskell tool/library/.., you'll want to let everyone know that it is still alive and actively maintained, even if there may have been no new additions (and even more so if there have been new developments). Tutorials: if you've fought with some previously undocumented corner of Haskell, and have been kind enough to write down how you did manage to build that networking program, or if you've written a tutorial about some useful programming techniques/patterns, this is your opportunity to spread the word (btw, short, topic-specific, and hands-on tutorials that only show how to achieve a certain practical task would do a lot to make things easier for new Haskellers - Erlang and Perl folks seem to be good at this kind of thing, but why not have a similar effort for Haskell?) Applications: if you've been working quietly, using Haskell for some interesting project or application (commercial or otherwise), you might want to let others know about what you're using Haskell for, and about your experiences using the existing tools and libraries; are you using Haskell on your job? There was an interesting thread about using Haskell for non-Haskell things not too long ago - why not write a sentence or two about your use of Haskell for our report? Feedback: if you're on one of the many specialist Haskell mailing lists, you'll want to report on whatever progress has been made there (GUI API discussions, library organisation, etc.) If you're unsure whether a contact for your area of work has come forward yet, have a look at the report's potential topics page, or get in touch with me. I've contacted last time's contributors, hoping they will volunteer to provide updates of their reports, and will update the contacts on the topics page fairly regularly. But where you don't yet see contacts listed for your own subject of interest, you are very welcome to volunteer, or to remind your local community/project team/mailing list/research group/etc. that they really ought to get their act together and let the Haskell community as a whole know about what they've been doing!-) --------------------------------- what should I write? That depends on your topic, but as a general rule, it shouldn't take you long. A simple sentence or two about your use of Haskell could go into the "Individual Haskellers and their projects" section. If you're a company, or if you're working on a project using Haskell as the implementation language, a paragraph on that could go into the "Commercial Applications" and "Non-Commercial Applications" sections. A typical summary report about a tool/library/project/application/.. would be between 1 and 3 paragraphs of ASCII text (what's it about? major topics and results since the last report? current hot topics? major goals for the next six months?) plus pointers to material for further reading (typically to a home page, or to mailing list archives, specifications and drafts, implementations, meetings, minutes,..). For those who prefer templates to fill in, the report is edited in LaTeX, and an entry template might look something like this: \subsubsection{<MYSTUFF>} \report{<MY NAME}\\ <WHAT IS IT?> <WHAT IS ITS STATUS? / WHAT HAS HAPPENED SINCE LAST TIME?> <CAN OTHERS GET IT?> <WHAT ARE THE IMMEDIATE PLANS?> \FurtherReading \url{<PROJECT URL>} Browsing through previous editions should give you a good idea of the variety of possibilities, ranging from very brief to extensive.

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HaRe 0.1 updates, and ghc-6.0.1
by C.Reinke 20 Oct '03

20 Oct '03

Since releasing version 0.1 of the Haskell Refactorer HaRe, we've continued to update the HaRe snapshots on our webpage every now and then, in response to your feedback and bug reports. http://www.cs.kent.ac.uk/projects/refactor-fp/hare.html We do not usually announce every new snapshot here, but there have been several requests for making HaRe build with ghc-6.0.1, and, since last week, the snapshots include the necessary workarounds. Apart from several smaller things, the current snapshot (20/10/2003) also includes a fix for one rather substantial bug in introNewDef and generaliseDef; String and Char literals should also no longer cause problems (see README.txt). So, if this has been keeping you from playing with HaRe, you might want to check again (and please keep those experience/bug reports and suggestions coming!-). Happy Refactoring! The HaRe Team (Huiqing Li, Claus Reinke, Simon Thompson)

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