- Glasgow-haskell-users

setCurrentDirectory and lightweight threads
by Niklas Broberg 24 Oct '04

24 Oct '04

Hello fellow Haskelleers, I've come upon a problem that sort of bites me. I'm writing a multithreaded webserver in which pages are dynamically loaded haskell applications. The main server loop listens for incoming requests and distributes these to request handlers, each running in a separate lightweight thread. Now, some of the most common operations used in dynamic web pages relate to directory listing/manipulation. I was happily thinking that System.Directory would provide the needed functionality. Indeed it does, but unfortunately setCurrentDirectory breaks the thread abstraction. What I mean is that if one page wants to change directory using setCurrentDirectory, this change affects all other (lightweight) threads as well, which is not how "ordinary" system threads works. Also it is clearly not what one would want in the kind of application I'm writing. Is this behavior of setCurrentDirectory intended? I can't see a situation in which you could take advantage of it, but that doesn't mean there can't be any. =) If it is not intended, is there any hope of it being "fixed"? Regards, /Niklas

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Change in ghc-6.2.2 distribution files
by Gregory Wright 23 Oct '04

23 Oct '04

Hi, Did the file ghc-6.2.2.tar.bz2 get changed without the version number being changed? The md5 sum of the files has changed, breaking the darwinports and presumably the *BSD ports builds as well. I didn't see any notice to the list, so I'm not sure if the change is intentional, or if the wrong file is being distributed. Best Wishes, Greg

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Mutable hash?
by Petter Egesund 23 Oct '04

23 Oct '04

Does anybody know about a mutable hash implementation for ghc? There is going to be a lot of updates in the hash (some millions adds and removes) so a non-mutable structure will not do?! Cheers, Petter ########################################### This message has been scanned by F-Secure Anti-Virus for Microsoft Exchange. For more information, connect to http://www.F-Secure.com/

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ANNOUNCE: GHC version 6.2.2
by Simon Marlow 22 Oct '04

22 Oct '04

============================================================= The (Interactive) Glasgow Haskell Compiler -- version 6.2.2 ============================================================= The GHC Team is pleased to announce the latest patchlevel release of GHC, 6.2.2. This is a bugfix release only, there are no new features. Code that worked with 6.2.1 will work unchanged with 6.2.2. A lot of bugfixes have gone into 6.2.2; we believe it is one of the most stable releases of GHC ever. Thanks to everyone who has been involved in testing pre-releases and submitting bug reports. This will also be the last release along the 6.2 branch, the next release (out "soon") will be 6.4 with plenty of new features. How to get it ~~~~~~~~~~~~~ The easy way is to go to the WWW page, which should be self-explanatory: http://www.haskell.org/ghc/ We supply binary builds in the native package format for various flavours of Linux and BSD, and in Windows Installer (MSI) form for Windows folks. Binary builds for other platforms are available as a .tar.gz which can be installed wherever you want. The source distribution is also available from the same place. Packages will appear as they are built - if the package for your system isn't available yet, please try again later. Background ~~~~~~~~~~ Haskell is a standard lazy functional programming language; the current language version is Haskell 98, agreed in December 1998 and revised December 2002. GHC is a state-of-the-art programming suite for Haskell. Included is an optimising compiler generating good code for a variety of platforms, together with an interactive system for convenient, quick development. The distribution includes space and time profiling facilities, a large collection of libraries, and support for various language extensions, including concurrency, exceptions, and foreign language interfaces (C, whatever). GHC is distributed under a BSD-style open source license. A wide variety of Haskell related resources (tutorials, libraries, specifications, documentation, compilers, interpreters, references, contact information, links to research groups) are available from the Haskell home page (see below). On-line GHC-related resources ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Relevant URLs on the World-Wide Web: GHC home page http://www.haskell.org/ghc/ Haskell home page http://www.haskell.org/ comp.lang.functional FAQ http://www.cs.nott.ac.uk/~gmh/faq.html System requirements ~~~~~~~~~~~~~~~~~~~ To compile programs with GHC, you need a machine with 64+MB memory, GCC and perl. This release is known to work on the following platforms: * i386-unknown-{linux,*bsd,mingw32} * sparc-sun-solaris2 * powerpc-apple-darwin (MacOS X) Ports to other platforms are possible with varying degrees of difficulty. The builder's guide on the web site gives a complete run-down of what ports work and how to go about porting to a new platform; it can be found at http://www.haskell.org/ghc/docs/latest/html/building/building-guide.html Mailing lists ~~~~~~~~~~~~~ We run mailing lists for GHC users and bug reports; to subscribe, use the web interfaces at http://www.haskell.org/mailman/listinfo/glasgow-haskell-users http://www.haskell.org/mailman/listinfo/glasgow-haskell-bugs There are several other haskell and ghc-related mailing lists on www.haskell.org; for the full list, see http://www.haskell.org/mailman/listinfo/ Please report bugs using our SourceForge page at http://sourceforge.net/projects/ghc/ or send them to glasgow-haskell-bugs(a)haskell.org. GHC users hang out on glasgow-haskell-users(a)haskell.org. Bleeding edge CVS users party on cvs-ghc(a)haskell.org.

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RE: Top level mutable data structures problem
by Simon Peyton-Jones 22 Oct '04

22 Oct '04

Lots of schemes have been discussed. The one I understand best is: * Modules can contain top-level bindings like x <- e where e:: IO t, and x::t * The IO actions from these bindings are composed, in order of appearance, and together comprise the "module initialisation action" * When a program is started, the module initialisation actions of its modules run, in an order that respects module dependencies. * "Respecting module dependencies" means that if M imports N (directly or indirectly) then N's initialisation is done before M's. Hi-boot recursive dependencies are not taken into account; that's where any module loops are broken That's simple, and easy to describe. It does not fully prescribe the initialisation order, but the programmer can constrain the order as much as required, by adding 'import' declarations. That's way better than the situation today, where the moment at which these actions take place is totally unpredictable. As Simon M says, don't hold your breath... but I'd be interested to know a) whether this story commands a consensus b) how much happier your life would be if it were implemented Simon | -----Original Message----- | From: glasgow-haskell-users-bounces(a)haskell.org [mailto:glasgow-haskell-users- | bounces(a)haskell.org] On Behalf Of Simon Marlow | Sent: 20 October 2004 15:47 | To: Adrian Hey; glasgow-haskell-users(a)haskell.org | Subject: RE: Top level mutable data structures problem | | On 20 October 2004 14:36, Adrian Hey wrote: | | > [Excuse me for moving this discussion to the ghc mailing list, | > but it seems the appropriate place, seeing as ghc is where | > any solution will happen first in all probability.] | > | > I've noticed that the neither of the two Simons has expressed an | > opinion re. the discussions on this issue that occurred on the | > Haskell mailing list over the weekend. So I'd like to ask what's | > happening (or likely to happen) about this, if anything? | | I liked the original idea. I'm not sure if I agree with the argument | that allowing fully-fledged IO actions in the initialisation of a module | is unsafe. I agree that it is a little opaque, in the sense that one | can't easily tell whether a particular init action is going to run or | not. | | On the other hand, instances currently have the same "problem": you | can't tell what instances are in scope in your module without looking | through the transitive closure of modules you import, including | libraries, which you might not have source code for. | | The proposed scheme wouldn't allow forcing an ordering on init actions | between two modules (eg. initialise the network library, then initialise | the HTTP library). | | In any case, we're not going to rush to implement anything. Discuss it | some more ;-) | | Cheers, | Simon | _______________________________________________ | Glasgow-haskell-users mailing list | Glasgow-haskell-users(a)haskell.org | http://www.haskell.org/mailman/listinfo/glasgow-haskell-users

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Profiling code using HaXml
by Carsten Schultz 22 Oct '04

22 Oct '04

Hi! Is there anybody who has compiled a profiling version of the HaXml libraries and might share a suitable make file? Greetings, Carsten -- Carsten Schultz (2:38, 33:47), FB Mathematik, FU Berlin http://carsten.codimi.de/ PGP/GPG key on the pgp.net key servers, fingerprint on my home page.

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TH2 bug
by MR K P SCHUPKE 22 Oct '04

22 Oct '04

Just reporting a bug, taking types using '' works fine for: ''Int ''[] But when you try: ''(->) you get: No match in record selector TyCon.algTcRhs Please report it as a compiler bug to glasgow-haskell-bugs(a)haskell.org, or http://sourceforge.net/projects/ghc/. Keean.

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template-haskell names in 6.3
by MR K P SCHUPKE 22 Oct '04

22 Oct '04

I have now read most of the notes on template-haskell2, but I still have a problem with naming (although I think my issues with types are adequately dealt with by the '' notation. I wish to create a declaration in template haskell, where the funtion name is supplied: something like: $(label "myLabel") However I wish the reference to this label to be globally specific to the generated instance... an example of this would be a function that prints its reified name: $(example "myLabel") would splice: myLabel :: String myLabel = "This_module.myLabel" mkName only returns the 'local' namem how can I get a global name from a string? Keean.

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CVS HEAD ghc fails with "Panic!"
by Peter Simons 21 Oct '04

21 Oct '04

Hi, the GHC version from the current CVS HEAD aborts with an internal error when doing this: $ darcs get http://cryp.to/hsemail $ cd hsemail $ ghc -O2 --make -o message-test message-test.hs | Chasing modules from: message-test.hs | Compiling Rfc2234 ( ./Rfc2234.hs, ./Rfc2234.o ) | ghc-6.3: panic! (the `impossible' happened, GHC version 6.3): | app_match: unbound tpl c{tv a1a9} Compiling with -O instead of -O2 works, though. Peter

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RE: Top level mutable data structures problem
by Simon Marlow 21 Oct '04

21 Oct '04

On 20 October 2004 14:36, Adrian Hey wrote: > [Excuse me for moving this discussion to the ghc mailing list, > but it seems the appropriate place, seeing as ghc is where > any solution will happen first in all probability.] > > I've noticed that the neither of the two Simons has expressed an > opinion re. the discussions on this issue that occurred on the > Haskell mailing list over the weekend. So I'd like to ask what's > happening (or likely to happen) about this, if anything? I liked the original idea. I'm not sure if I agree with the argument that allowing fully-fledged IO actions in the initialisation of a module is unsafe. I agree that it is a little opaque, in the sense that one can't easily tell whether a particular init action is going to run or not. On the other hand, instances currently have the same "problem": you can't tell what instances are in scope in your module without looking through the transitive closure of modules you import, including libraries, which you might not have source code for. The proposed scheme wouldn't allow forcing an ordering on init actions between two modules (eg. initialise the network library, then initialise the HTTP library). In any case, we're not going to rush to implement anything. Discuss it some more ;-) Cheers, Simon

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