[Haskell-cafe] Don't miss CUFP
Hey, guys, This list has zillions of people who use Haskell for day-to-day work. So you might want to come to the now-annual workshop for Commercial Users of Functional Programming (CUFP) http://cufp.galois.com 4 Sept 2009, Edinburgh Speakers from companies including Facebook, Barclays Capital, and EDF Trading, using Haskell, Scala, F#, among others. Better still, CUFP is preceded and followed by a day of developer-focused tutorials: Developer Tracks on Functional Programming http://www.defun2009.info/blog/ 3 and 5 Sept, Edinburgh Tutorials covering tools and libraries in Erlang, OCaml, Scala, PLT Scheme, and more. And if that isn't enough, all this is co-located with International Conference on Functional Programming (ICFP) Haskell Symposium ML Workshop Generic Programming Workshop Erlang Workshop Haskell Implementors Workshop Such a cornucopia of delights. It'll be fun. But you do have to register: http://www.cs.nott.ac.uk/~gmh/icfp09.html Simon ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Static linking
Hello, I wrote a small installer program which configures and installs some software packages. In order to be able to let it run on a different machine, where I possibly don't have the needed shared libraries, I tried to link it statically, following this advice: http://www.haskell.org/haskellwiki/Practical_web_programming_in_Haskell#Deployin g_statically_linked_applications However I get some linking errors: ghc --make Installer.hs -static -optl-static /usr/lib/ghc-6.10.3/unix-2.3.2.0/libHSunix-2.3.2.0.a(User__143.o)(.text+0xf1): In function `s7Tu_info': : warning: Using 'getgrnam_r' in statically linked applications requires at runtime the shared libraries from the glibc version used for linking /usr/lib/gcc-lib/i586-suse-linux/3.3.3/../../../libedit.a(readline.o)(.text+0x7b 2): In function `username_completion_function': /home/oswald/build/libedit-20090610-3.0/src/readline.c:1467:0: warning: Using 'getpwent' in statically linked applications requires at runtime the shared libraries from the glibc version used for linking src/dlmalloc.c:2486:0: undefined reference to `pthread_mutex_lock' /usr/lib/ghc-6.10.3/libffi.a(closures.o)(.text+0x132):src/dlmalloc.c:2493: undefined reference to `pthread_mutex_unlock' /usr/lib/ghc-6.10.3/libffi.a(closures.o)(.text+0x184):src/dlmalloc.c:2490: undefined reference to `pthread_mutex_init' /usr/lib/ghc-6.10.3/libffi.a(closures.o)(.text+0x227): In function `ffi_closure_free': Because of the undefined references to pthread_mutex_lock I then tried various versions of ghc --make Installer.hs -static -optl-static -lpthread -lrt and reordered the -l switches, but neither combination helped. I always get the same error. Does somebody know how to correctly specify the pthread library for this? lg, Michael ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: Static linking
Marcin Kosiba marcin.kosiba at gmail.com writes: Try: ghc --make Installer.hs -static -optl-static -optl-pthread Ah, that fixed it. Thanks a lot! If that doesn't work, you can always do a ghc -v, find the command it uses for linking, modify it and run it manually. Peter suggested this, but I ran into other problems. But since it works now, I'm happy with it! Thanks again! lg, Michael ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ANN: darcs 2.3.0
Great! Just a little note: MSYS isn't required to install Darcs with cabal on Windows, just to develop or run tests. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Static linking
On Friday 24 July 2009, Michael Oswald wrote: Hello, I wrote a small installer program which configures and installs some software packages. In order to be able to let it run on a different machine, where I possibly don't have the needed shared libraries, I tried to link it statically, following this advice: http://www.haskell.org/haskellwiki/Practical_web_programming_in_Haskell#Dep loyin g_statically_linked_applications However I get some linking errors: ghc --make Installer.hs -static -optl-static /usr/lib/ghc-6.10.3/unix-2.3.2.0/libHSunix-2.3.2.0.a(User__143.o)(.text+0xf 1): In function `s7Tu_info': : warning: Using 'getgrnam_r' in statically linked applications requires at runtime the shared libraries from the glibc version used for linking /usr/lib/gcc-lib/i586-suse-linux/3.3.3/../../../libedit.a(readline.o)(.text +0x7b 2): In function `username_completion_function': /home/oswald/build/libedit-20090610-3.0/src/readline.c:1467:0: warning: Using 'getpwent' in statically linked applications requires at runtime the shared libraries from the glibc version used for linking src/dlmalloc.c:2486:0: undefined reference to `pthread_mutex_lock' /usr/lib/ghc-6.10.3/libffi.a(closures.o)(.text+0x132):src/dlmalloc.c:2493: undefined reference to `pthread_mutex_unlock' /usr/lib/ghc-6.10.3/libffi.a(closures.o)(.text+0x184):src/dlmalloc.c:2490: undefined reference to `pthread_mutex_init' /usr/lib/ghc-6.10.3/libffi.a(closures.o)(.text+0x227): In function `ffi_closure_free': Because of the undefined references to pthread_mutex_lock I then tried various versions of ghc --make Installer.hs -static -optl-static -lpthread -lrt and reordered the -l switches, but neither combination helped. I always get the same error. Does somebody know how to correctly specify the pthread library for this? Hi, Try: ghc --make Installer.hs -static -optl-static -optl-pthread If that doesn't work, you can always do a ghc -v, find the command it uses for linking, modify it and run it manually. Thanks! Marcin Kosiba signature.asc Description: This is a digitally signed message part. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: ANN: darcs 2.3.0
Salvatore Insalaco kirb...@gmail.com writes: Great! Just a little note: MSYS isn't required to install Darcs with cabal on Windows, just to develop or run tests. Oh, good to know. I had no idea you could use cmd.exe to run cabal and darcs and that it would work. Yours, Petr. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] ANN: Leksah 0.6
Hi, Just a quick note to let people know we released a new version of Leksah this week. Thanks for the help and feedback on the previous version. We have done our best to add the features we thought were most pressing. Please give it a go and let us know what features you would like to see most in the future. http://leksah.org/ __ What's New __ * Integrated GHCi based debugging * Multi-window support (View - Detach) * Improved layout control (drag drop and nesting) * Regular expression find and replace * Grep files in the current package * Improved Mac OS X integration __ Known Bugs and Problems __ * The package editor works only for cabal files without configurations. * MS Windows: The check for external modifications of source files does not work. * MS Windows: Interruption of a background build does not work. * Navigation in Trace history does not work. Mac OSX users can install using Mac Ports as usual or use the provided Intel binary (tested on Leopard only). http://leksah.org/Leksah-0.6.1.0.dmg Hamish ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ANN: Leksah 0.6
On 24 Jul 2009, at 15:52, Hamish Mackenzie wrote: Hi, Just a quick note to let people know we released a new version of Leksah this week. Thanks for the help and feedback on the previous version. We have done our best to add the features we thought were most pressing. Please give it a go and let us know what features you would like to see most in the future. http://leksah.org/ __ What's New __ * Integrated GHCi based debugging * Multi-window support (View - Detach) * Improved layout control (drag drop and nesting) * Regular expression find and replace * Grep files in the current package * Improved Mac OS X integration __ Known Bugs and Problems __ * The package editor works only for cabal files without configurations. * MS Windows: The check for external modifications of source files does not work. * MS Windows: Interruption of a background build does not work. * Navigation in Trace history does not work. Mac OSX users can install using Mac Ports as usual or use the provided Intel binary (tested on Leopard only). http://leksah.org/Leksah-0.6.1.0.dmg The new detach feature is great, it makes it much more usable for OS X users, but there's a small problem – if you detach the main source window (from the default config), you end up with a window containing just the package management/documentation stuff, which is great, but I'd like to be able to shrink it down. You can't unfortunately because of the toolbar. Would it be possible to move the toolbar onto the document windows rather than the package window.___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ANN: Leksah 0.6
The Mac Binary is a great addition! :-) Thanks! On Fri, Jul 24, 2009 at 6:52 AM, Hamish Mackenzie ham...@firestream.co.ukwrote: Hi, Just a quick note to let people know we released a new version of Leksah this week. Thanks for the help and feedback on the previous version. We have done our best to add the features we thought were most pressing. Please give it a go and let us know what features you would like to see most in the future. http://leksah.org/ __ What's New __ * Integrated GHCi based debugging * Multi-window support (View - Detach) * Improved layout control (drag drop and nesting) * Regular expression find and replace * Grep files in the current package * Improved Mac OS X integration __ Known Bugs and Problems __ * The package editor works only for cabal files without configurations. * MS Windows: The check for external modifications of source files does not work. * MS Windows: Interruption of a background build does not work. * Navigation in Trace history does not work. Mac OSX users can install using Mac Ports as usual or use the provided Intel binary (tested on Leopard only). http://leksah.org/Leksah-0.6.1.0.dmg Hamish ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: System.Mem.performGC leaks?
On 23/07/2009 11:53, Simon Marlow wrote: On 22/07/2009 02:51, Neal Alexander wrote: Neal Alexander wrote: Compiled with ghc -O2 -fvia-C -optc-O2 -funbox-strict-fields -threaded btw. GHC 6.10.3 on 64bit windows7. Interesting. It's completely flat on Linux, but gobbles up about 1MB/s on Windows. I'm investigating. Found it - there was a CriticalSection being re-initialised at each GC. Cheers, Simon ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: [Haskell] ANN: yices 0.0.0.1 - Haskell programming interface to Yices SMT solver
You may want to take a look at this, as well: http://www.sivity.net/projects/smt-yices Aaron On Jul 23, 2009, at 5:32 PM, Ahn, Ki Yung wrote: http://hackage.haskell.org/package/yices Incomplete (no bitvectors) syntax, parser, and inter process communication to Yices from Haskell through pipe. Purpose for building and using this library was to generate test cases from constraints that SMT solvers can solve. I only used it for that particular purpose, so the code in general is not yet fully tested. Use at your own risk and error reports are welcomed. See http://yices.csl.sri.com/ for further information on Yices. Note: this package does not include Yices. You should get it from the Yices homepage and install it before using this library. @ If you already have a better API for Yices or other SMT solvers, and if you can open the source please upload it to hacakage. That would be great help for some people. -- Ahn, Ki Yung ___ Haskell mailing list hask...@haskell.org http://www.haskell.org/mailman/listinfo/haskell -- Aaron Tomb Galois, Inc. (http://www.galois.com) at...@galois.com Phone: (503) 626-6616 ext. 156 Fax: (503) 350-0833 ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ANN: Leksah 0.6
2009/7/25 Thomas Davie tom.da...@gmail.com: The new detach feature is great, it makes it much more usable for OS X users, but there's a small problem – if you detach the main source window (from the default config), you end up with a window containing just the package management/documentation stuff, which is great, but I'd like to be able to shrink it down. You can't unfortunately because of the toolbar. Would it be possible to move the toolbar onto the document windows rather than the package window. Try this... start with the default layout (rm ~/.leksah/Current.session) click on the Modules tab (make sure it says Modules in the status bar) View - Collapse (this will combine the two panes on the right into one) View - Detach (this will detach them leaving the main toolbar behind) Hamish ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ANN: Leksah 0.6
Now updating metadata ... Why does it need more than 3GB of RAM at this point (I have 4GB and see 70% going to Leksah before I kill it)? I didn't point it at _that_ much Haskell code to parse though. Does it read everything into some bloated internal format before parsing? Thomas On Fri, Jul 24, 2009 at 6:52 AM, Hamish Mackenzieham...@firestream.co.uk wrote: Hi, Just a quick note to let people know we released a new version of Leksah this week. Thanks for the help and feedback on the previous version. We have done our best to add the features we thought were most pressing. Please give it a go and let us know what features you would like to see most in the future. http://leksah.org/ __ What's New __ * Integrated GHCi based debugging * Multi-window support (View - Detach) * Improved layout control (drag drop and nesting) * Regular expression find and replace * Grep files in the current package * Improved Mac OS X integration __ Known Bugs and Problems __ * The package editor works only for cabal files without configurations. * MS Windows: The check for external modifications of source files does not work. * MS Windows: Interruption of a background build does not work. * Navigation in Trace history does not work. Mac OSX users can install using Mac Ports as usual or use the provided Intel binary (tested on Leopard only). http://leksah.org/Leksah-0.6.1.0.dmg Hamish ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ANN: Leksah 0.6
On 24 Jul 2009, at 18:01, Hamish Mackenzie wrote: 2009/7/25 Thomas Davie tom.da...@gmail.com: The new detach feature is great, it makes it much more usable for OS X users, but there's a small problem – if you detach the main source window (from the default config), you end up with a window containing just the package management/documentation stuff, which is great, but I'd like to be able to shrink it down. You can't unfortunately because of the toolbar. Would it be possible to move the toolbar onto the document windows rather than the package window. Try this... start with the default layout (rm ~/.leksah/Current.session) click on the Modules tab (make sure it says Modules in the status bar) View - Collapse (this will combine the two panes on the right into one) View - Detach (this will detach them leaving the main toolbar behind) Perfect :) Leksah is looking really rather impressive, I look forward to seeing what else you do with it. Bob___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ANN: Leksah 0.6
thomas.dubuisson: Now updating metadata ... How many packages do you have installed? :-) Why does it need more than 3GB of RAM at this point (I have 4GB and see 70% going to Leksah before I kill it)? I didn't point it at _that_ much Haskell code to parse though. Does it read everything into some bloated internal format before parsing? ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] QuickCheck behaving strange
Hey Guys! I was writing a small implementation of the earliest-end-first algorithm for the Interval Scheduling problem just now. When I was done, I thought it would be a nice thing to have a QuickCheck property for my code. This is what I came up with: -- Intervals are just triplets type Interval a t = (a,t,t) end :: Interval a t - t end (_,_,t) = t begin :: Interval a t - t begin (_,t,_) = t And so the property: prop_schedule :: Ord t = [Interval a t] - Bool prop_schedule []= True prop_schedule [a] = True prop_schedule (x:y:ys) = end x = begin y prop_schedule (y:ys) Essentially, it looks up wheather the given list is sorted (given the constraints of the problem). However, in this property I forgot to add that the lists should have been run through my algorithm, which I noticed only after this strange problem appeared: *Interval quickCheck prop_schedule +++ OK, passed 100 tests. How come QuickCheck passes 100 tests of random lists? One would think that at least one of the generated lists would be unsorted. It also passes 1000 and even 1 tests. It also seems that changing the type helps: prop_schedule :: [Interval a Int] - Bool ... *Interval quickCheck prop_schedule *** Failed! Falsifiable (after 5 tests and 1 shrink): [((),0,0),((),-1,0)] -- Tobias Olausson tob...@gmail.com ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] QuickCheck behaving strange
On Fri, Jul 24, 2009 at 08:11:12PM +0200, Tobias Olausson wrote: prop_schedule :: Ord t = [Interval a t] - Bool prop_schedule []= True prop_schedule [a] = True prop_schedule (x:y:ys) = end x = begin y prop_schedule (y:ys) [..] How come QuickCheck passes 100 tests of random lists? One would think that at least one of the generated lists would be unsorted. It also passes 1000 and even 1 tests. Probably it was defaulting to 'Interval () ()'. Try to do :s -Wall on your GHCi prompt to see when these things happen. -- Felipe. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] QuickCheck behaving strange
On Fri, Jul 24, 2009 at 11:29 AM, Felipe Lessa felipe.le...@gmail.comwrote: On Fri, Jul 24, 2009 at 08:11:12PM +0200, Tobias Olausson wrote: prop_schedule :: Ord t = [Interval a t] - Bool prop_schedule []= True prop_schedule [a] = True prop_schedule (x:y:ys) = end x = begin y prop_schedule (y:ys) [..] How come QuickCheck passes 100 tests of random lists? One would think that at least one of the generated lists would be unsorted. It also passes 1000 and even 1 tests. Probably it was defaulting to 'Interval () ()'. Try to do Cases like this make me feel as though the instance of Ord for () was a mistake. Jason ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] QuickCheck behaving strange
It seems this was the case, thank you! /Tobias 2009/7/24 Felipe Lessa felipe.le...@gmail.com: On Fri, Jul 24, 2009 at 08:11:12PM +0200, Tobias Olausson wrote: prop_schedule :: Ord t = [Interval a t] - Bool prop_schedule [] = True prop_schedule [a] = True prop_schedule (x:y:ys) = end x = begin y prop_schedule (y:ys) [..] How come QuickCheck passes 100 tests of random lists? One would think that at least one of the generated lists would be unsorted. It also passes 1000 and even 1 tests. Probably it was defaulting to 'Interval () ()'. Try to do :s -Wall on your GHCi prompt to see when these things happen. -- Felipe. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe -- Tobias Olausson tob...@gmail.com ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ANN: Leksah 0.6
On Fri, Jul 24, 2009 at 11:08 AM, Don Stewartd...@galois.com wrote: thomas.dubuisson: Now updating metadata ... How many packages do you have installed? :-) 90 packages - so no more than most other devs I think. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] QuickCheck behaving strange
I've felt a bit stupid using instance Monoid ()... but it seemed quite natural. On 24 Jul 2009, at 22:33, Jason Dagit wrote: On Fri, Jul 24, 2009 at 11:29 AM, Felipe Lessa felipe.le...@gmail.com wrote: On Fri, Jul 24, 2009 at 08:11:12PM +0200, Tobias Olausson wrote: prop_schedule :: Ord t = [Interval a t] - Bool prop_schedule []= True prop_schedule [a] = True prop_schedule (x:y:ys) = end x = begin y prop_schedule (y:ys) [..] How come QuickCheck passes 100 tests of random lists? One would think that at least one of the generated lists would be unsorted. It also passes 1000 and even 1 tests. Probably it was defaulting to 'Interval () ()'. Try to do Cases like this make me feel as though the instance of Ord for () was a mistake. Jason ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Haskell on a VPS
On Thu, Jul 23, 2009 at 6:12 PM, John Van Enkvane...@gmail.com wrote: No, I just want to know if there are any gotchas in the typical VPS setups that for some strange reason wouldn't like Haskell binaries. I couldn't think of any, but I miss details some times. There used to be problems with ghci running under the virtualization software Xen on x86_64 which is a common setup for VPS. As far as I can tell these problems have been resolved. http://hackage.haskell.org/trac/ghc/ticket/2512 http://hackage.haskell.org/trac/ghc/ticket/2063 ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re:Haskell-Cafe Digest, Vol 71, Issue 30
On Tue, 21 Jul 2009 09:39:59 +0200, silent_stream silent_str...@126.com wrote: When I compile curl-1.3.5 on Windows xp. I run the prompt runghc Setup.hs configure I got the following error Setup.hs: Missing dependency on a foreign library: * Missing C library: curl This problem can usually be solved by installing the system package that provides this library (you may need the -dev version). If the library is already installed but in a non-standard location then you can use the flags --extra-include-dirs= and --extra-lib-dirs= to specify where it is. I don't know how to fix this problem. Who knows? Please come to help me . This message means that the curl package depends on the curl package written in C; to get the C curl package, go to http://curl.haxx.se/download.html and download the proper package (for example http://curl.haxx.se/download/curl-7.19.5-win32-ssl-sspi.zip ) and unpack it into a directory with no space in the path name, e.g.: C:\temp\curl-7.19.5 If you do not have MingW/MSYS installed, do it now[1], you will need it for other packages as well. Open a DOS shell and go to the curl C package directory, give command: make ; it will take several minutes to build. Copy the contents of directory C:\temp\curl-7.19.5\include\curl to a directory where you collect .h files for linking, e.g.: C:\usr\local\include\curl Copy the contents of directory C:\temp\curl-7.19.5\lib\.libs to a directory where you collect library files for linking, e.g.: C:\usr\local\lib\curl To let the compiler find the necessary files, set environment variables: set C_INCLUDE_PATH=C:\usr\local\include set LIBRARY_PATH=C:\usr\local\lib;C:\usr\local\lib\curl Now you will be able to compile the Haskell curl package. [1] http://www.haskell.org/haskellwiki/Windows#Tools_for_compilation -- Met vriendelijke groet, Henk-Jan van Tuyl -- http://functor.bamikanarie.com http://Van.Tuyl.eu/ -- ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] lifting restrictions on defining instances
David Menendez wrote: wren ng thornton wrote: John Lask wrote: Can anyone explain the theoretical reason for this limitation, ie other than it is a syntactical restriction, what would it take to lift this restriction ? There are a couple of theoretical concerns, mainly that full type-level lambdas can lead down a rocky path (though simple combinators like `flip` and `const` are fine, and that's all we'd need for most cases). But by and large it's just a syntactic restriction. I wouldn't say it's just a syntactic restriction. I'm pretty sure unrestricted type lambdas are incompatible with Haskell's class system. Otherwise, you might end up with Functor instances for /\b. (a,b) and /\a. (a,b), at which point fmap (+1) (1,2) is ambiguous. This is essentially the same problem as arises with overlapping instances. It is a new version of that problem since it introduces new places for overlapping (by highlighting the fact that instances on a *-* kind are actually instances on type-level lambdas), but the problem isn't exactly a new one. A tweak of the overlap detector should be able to catch these too; eta expand and check for overlap of the type-level terms. The definition of overlap is somewhat different since it must respect abstraction, but it's not too much different than the current version. It is still possible to use type signatures to clear things up, albeit much uglier than usual. If we were to head down the road of type-level lambdas then we would want some mechanism for making it easier to deal with bifunctors like (,) and similar issues. The easiest thing, perhaps, would be to expose some of the explicit type passing that happens in the System F core[1], though we'd want to massage the dictionary-passing so that we could say things like (fmap @A) to mean the fmap of the instance for A. So yes, implementing type-level lambdas is more than just changing the parser (so more than just syntax), but provided the right restrictions on what type-level lambdas are acceptable I don't think there are any substantial theoretical issues (so I'd say it's just syntax, rather than theoretical concerns). And these restrictions are the obvious ones, mainly blocking recursion to prevent the compiler from hanging or generating infinite types. [1] In System F the capital-lambda binder is used for the term-level abstraction of passing type representations. So for example we have, id :: forall a. a - a id = /\a. \(x::a). x Thus, the forall keyword is serving as the type-level abstraction. Perhaps this is suboptimal syntax, but it is the standard. We could, of course, have both a term-level /\ and a type-level /\ where the latter is the type of the former (since the namespaces are separate) though that's also dubious. Capital-pi is the canonical type-level abstraction, though that evokes the idea of dependent types which are much more complex. -- Live well, ~wren ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ANN: Leksah 0.6
BTW, it works better when I don't give it a directory with numerous branches of Xen and the Linux kernel - somewhat unfortunate that this causes massive memory use. Now to figure out how to get it to properly configure/build projects! Thomas On Fri, Jul 24, 2009 at 11:44 AM, Thomas DuBuissonthomas.dubuis...@gmail.com wrote: On Fri, Jul 24, 2009 at 11:08 AM, Don Stewartd...@galois.com wrote: thomas.dubuisson: Now updating metadata ... How many packages do you have installed? :-) 90 packages - so no more than most other devs I think. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ANN: Leksah 0.6
Oh, so it is scanning all the files and not finalizing them? thomas.dubuisson: BTW, it works better when I don't give it a directory with numerous branches of Xen and the Linux kernel - somewhat unfortunate that this causes massive memory use. Now to figure out how to get it to properly configure/build projects! Thomas On Fri, Jul 24, 2009 at 11:44 AM, Thomas DuBuissonthomas.dubuis...@gmail.com wrote: On Fri, Jul 24, 2009 at 11:08 AM, Don Stewartd...@galois.com wrote: thomas.dubuisson: Now updating metadata ... How many packages do you have installed? :-) 90 packages - so no more than most other devs I think. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ANN: Leksah 0.6
Don Stewartd...@galois.com wrote: Oh, so it is scanning all the files and not finalizing them? That's the implication, but I can't seem to trigger the case short of [re]moving the .leksah directory and redoing the config that way... when I do that... A brief black-box view of it shows that it opens and closes all the files quite quickly (observed via lsof) then the CPU is pegged for a while (and I notice it's single threaded - any plans to process this stuff in parallel?). It remains pegged as the memory use gradually climbs up in steps of ~ 6% it looks like. Eventually I kill it before it becomes all knowing and breaks into our nuclear command and control under the name of 'SkyNet'. Thomas thomas.dubuisson: BTW, it works better when I don't give it a directory with numerous branches of Xen and the Linux kernel - somewhat unfortunate that this causes massive memory use. Now to figure out how to get it to properly configure/build projects! Thomas On Fri, Jul 24, 2009 at 11:44 AM, Thomas DuBuissonthomas.dubuis...@gmail.com wrote: On Fri, Jul 24, 2009 at 11:08 AM, Don Stewartd...@galois.com wrote: thomas.dubuisson: Now updating metadata ... How many packages do you have installed? :-) 90 packages - so no more than most other devs I think. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ANN: Leksah 0.6
thomas.dubuisson: Don Stewartd...@galois.com wrote: Oh, so it is scanning all the files and not finalizing them? That's the implication, but I can't seem to trigger the case short of [re]moving the .leksah directory and redoing the config that way... when I do that... A brief black-box view of it shows that it opens and closes all the files quite quickly (observed via lsof) then the CPU is pegged for a while (and I notice it's single threaded - any plans to process this stuff in parallel?). It remains pegged as the memory use gradually climbs up in steps of ~ 6% it looks like. Eventually I kill it before it becomes all knowing and breaks into our nuclear command and control under the name of 'SkyNet'. Yeah, I've had similar issues (but I have upwards of 500 packages installed). ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: Curl error message
On Fri, 24 Jul 2009 21:16:15 +0200, Henk-Jan van Tuyl hjgt...@chello.nl wrote: On Tue, 21 Jul 2009 09:39:59 +0200, silent_stream silent_str...@126.com wrote: When I compile curl-1.3.5 on Windows xp. I run the prompt runghc Setup.hs configure I got the following error Setup.hs: Missing dependency on a foreign library: * Missing C library: curl This problem can usually be solved by installing the system package that provides this library (you may need the -dev version). If the library is already installed but in a non-standard location then you can use the flags --extra-include-dirs= and --extra-lib-dirs= to specify where it is. I don't know how to fix this problem. Who knows? Please come to help me . This message means that the curl package depends on the curl package written in C; to get the C curl package, go to http://curl.haxx.se/download.html and download the proper package (for example http://curl.haxx.se/download/curl-7.19.5-win32-ssl-sspi.zip ) and unpack it into a directory with no space in the path name, e.g.: C:\temp\curl-7.19.5 If you do not have MingW/MSYS installed, do it now[1], you will need it for other packages as well. Open a DOS shell and go to the curl C package directory, give command: make ; it will take several minutes to build. Copy the contents of directory C:\temp\curl-7.19.5\include\curl to a directory where you collect .h files for linking, e.g.: C:\usr\local\include\curl Copy the contents of directory C:\temp\curl-7.19.5\lib\.libs to a directory where you collect library files for linking, e.g.: C:\usr\local\lib\curl To let the compiler find the necessary files, set environment variables: set C_INCLUDE_PATH=C:\usr\local\include set LIBRARY_PATH=C:\usr\local\lib;C:\usr\local\lib\curl Now you will be able to compile the Haskell curl package. [1] http://www.haskell.org/haskellwiki/Windows#Tools_for_compilation The Haskell curl package must also be in a directory without spaces in the name; the script used for installation cannot handle spaces in path. After moving the package to C:\temp, the package installs. -- Met vriendelijke groet, Henk-Jan van Tuyl -- http://functor.bamikanarie.com http://Van.Tuyl.eu/ -- ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] generalize RecordPuns and RecordWildCards to work with qualified names?
Hello,
I think that Even refers to an example like this:
module A where
data A = A { a :: Int }
The following works:
{-# LANGUAGE NamedFieldPuns #-}
module B where
import A
f (A { a }) = a
However, if we import A qualified, then punning does not seem to work:
{-# LANGUAGE NamedFieldPuns #-}
module B where
import qualified A
f (A.A { a }) = a
This results in: Not in scope: `a'
{-# LANGUAGE NamedFieldPuns #-}
module B where
import qualified A
f (A.A { A.a }) = a
This results in: Qualified variable in pattern: A.a
Even is suggesting that instead of reporting an error, in the second
case we could use the translation:
f (A.A { A.a }) = a
--
f (A.A { A.a = a })
(i.e., when punning occurs with a qualified name, use just the
unqualified part of the name in the pattern)
Hope that this helps,
-Iavor
On Thu, Jul 23, 2009 at 12:51 PM, Simon
Peyton-Jonessimo...@microsoft.com wrote:
Can you give a concrete program to illustrate your point, please? I'm not
getting it.
Simon
| -Original Message-
| From: haskell-cafe-boun...@haskell.org
[mailto:haskell-cafe-boun...@haskell.org] On
| Behalf Of Evan Laforge
| Sent: 17 July 2009 23:57
| To: haskell
| Subject: [Haskell-cafe] generalize RecordPuns and RecordWildCards to work
with
| qualified names?
|
| Record punning is not all that useful with qualified module names. If
| I write '(M.Record { M.rec_x })' it says Qualified variable in
| pattern and if I write '(M.Record { rec_x })' it says 'Not in scope:
| `rec_x''. Could it be this extension be further extended slightly so
| that 'f (M.Record { M.rec_x })' will desugar to 'f (M.Record { M.rec_x
| = rec_x })'?
|
| Similarly, RecordWildCards could support this too.
|
| It seems simple and useful to me... am I missing anything fatally
| problematic about this? Would anyone else use it?
| ___
| Haskell-Cafe mailing list
| Haskell-Cafe@haskell.org
| http://www.haskell.org/mailman/listinfo/haskell-cafe
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Re: [Haskell-cafe] Haskell on a VPS
At Thu, 23 Jul 2009 10:53:40 -0400, John Van Enk wrote: Has any one used a service similar to (or equivelant to) Slicehost or Linode to run Haskell network applications? Ok, I discovered an issue with some VPSes. There are two virtualization technologies in common use, OpenVZ and Xen. With Xen you can have swap, but with OpenVZ you don't. In my experience, apps compiled with GHC like to allocate a lot of virtual memory that they don't really seem to use. With Xen that is not a big deal, if you allocate memory, but don't actually use it, that's ok, because in theory it could be swapped out if you actually did use it. But with OpenVZ, just allocating the memory counts against your memory quota, even if you aren't actually using it for anything. So, in practice, I think you will get a lot more milege out of your VPS memory if you use Xen instead of OpenVZ, even if you never *actually* swap to disk on the Xen platform. There is some more information here: http://hostingfu.com/article/xen-or-openvz - jeremy ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: System.Mem.performGC leaks?
Simon Marlow wrote: On 23/07/2009 11:53, Simon Marlow wrote: On 22/07/2009 02:51, Neal Alexander wrote: Neal Alexander wrote: Compiled with ghc -O2 -fvia-C -optc-O2 -funbox-strict-fields -threaded btw. GHC 6.10.3 on 64bit windows7. Interesting. It's completely flat on Linux, but gobbles up about 1MB/s on Windows. I'm investigating. Found it - there was a CriticalSection being re-initialised at each GC. Cheers, Simon Cool, thanks for checking it out. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
