Re: [Haskell-cafe] deriving Data.HashTable - stack overflow
Ah, thanks, folks! I'll just implement my own hashing by generating a string and calling the hash function on that. That's what I was doing in the old version of my code, anyway. It's just that in the core Data.HashTable, you had to provide a hash function, so the point where I used the hash table was able to call a string conversion function that was defined elsewhere. With the hashtable package, you have to define a Hashable instance in the same package as your datatype definition - which is not where the string conversion is implemented. Calling the string conversion function leads to a cyclic dependency that I wanted to avoid. So I'll have to maybe move it to live with the datatype definition, or duplicate it, or use some other means of hashing. In other words, package A defines datatype A. Package B defines A - String. Package C creates a HashTable that indexes by As, and also imports package B, so it can build a hash function as the composition of the string conversion and the provided string hashing. But now I need to define the Hashable instance in A, which doesn't have access to package B, since package B also depends on A, and I don't like circular dependencies. - Lyle ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] deriving Data.HashTable - stack overflow
I chose not to introduce another dependency. I just implemented the hash function by delegating to the Show instance of the nested type: data ValType = FloatType | IntType | StringType deriving (Show,Eq) data VarName = VarName ValType String deriving (Show,Eq) instance Hashable VarName where hash (VarName t n) = hash (show t ++ n) Not super-efficient, but it'll be fine. The printString function (defined in that other package) uses a single character prefix for each ValType. - Lyle ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] deriving Data.HashTable - stack overflow
Here's another way to do it: data ValType = FloatType | IntType | StringType deriving (Show,Eq) instance Hashable ValType where hash FloatType = 0 hash IntType = 1 hash StringType = 2 data VarName = VarName ValType String deriving (Show,Eq) instance Hashable VarName where hash (VarName t n) = hash (t, n) ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] deriving Data.HashTable - stack overflow
Hi folks,
In GHC 7.6.3, the base Data.HashTable is deprecated, so I installed the
hashtables package. In order to work on your datatype, you need an instance
of Data.Hashable.Hashable.
So I went to the Data.Hashable page and looked up examples on how to derive
a Hashable instance for my datatype:
http://hackage.haskell.org/packages/archive/hashable/latest/doc/html/Data-Hashable.html
The problem occurs even when using the sample code on the page:
{-# LANGUAGE DeriveGeneric #-}
import GHC.Generics (Generic)
import Data.Hashable
data Colour = Red | Green | Blue
deriving Generic
instance Hashable Colour
If I then type `hash Red` I get a stack overflow.
I am using the Haskell Platform, so I have hashable-1.1.2.5, but I notice
the docs are for hashable-1.2.0.10. If I install 1.2.0.10 though, other
code in my project breaks - seems like one part doesn't recognize the
instances from another part. So I'll stick with the platform version.
I am running the 32-bit Windows GHC 7.6.3. Haskell Platform 2013.2.0.0.
Any thoughts?
Thanks,
Lyle
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[Haskell-cafe] Unable to install Haskell Platform without readline
Hi folks, I just installed GHC 6.10.4 on Ubuntu 9.04 32-bit, and then tried to install the Haskell Platform from source. It built quite a bit of stuff, with many warnings but no errors, and then finally died with the error below. To install editline, I need cabal, which is of course why I installed the Platform. I read an earlier thread from May that said that editline came with GHC 6.10.2, so the Platform didn't work with 6.10.3, but was soon to be updated. Now the web sitehttp://hackage.haskell.org/platform/contents.htmlfor the Platform says it comes with 6.10.4, so I assumed it should work with 6.10.4, but apparently it still has this problem of still missing editline. Am I doing something wrong? checking editline/readline.h usability... no checking editline/readline.h presence... no checking for editline/readline.h... no checking editline/editline.h usability... no checking editline/editline.h presence... no checking for editline/editline.h... no checking readline/readline.h usability... yes checking readline/readline.h presence... yes checking for readline/readline.h... yes checking for sign of read_history result on error... negative checking for rl_completion_matches... no checking for completion_matches... no configure: error: editline not found, so this package cannot be built See `config.log' for more details. Error: Configuring the editline-0.2.1.0 package failed make: *** [build.stamp] Error 2 - Lyle ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: Unable to install Haskell Platform without editline
I mean editline, not readline. On Fri, Sep 11, 2009 at 11:46 AM, Lyle Kopnicky li...@qseep.net wrote: Hi folks, I just installed GHC 6.10.4 on Ubuntu 9.04 32-bit, and then tried to install the Haskell Platform from source. It built quite a bit of stuff, with many warnings but no errors, and then finally died with the error below. To install editline, I need cabal, which is of course why I installed the Platform. I read an earlier thread from May that said that editline came with GHC 6.10.2, so the Platform didn't work with 6.10.3, but was soon to be updated. Now the web sitehttp://hackage.haskell.org/platform/contents.htmlfor the Platform says it comes with 6.10.4, so I assumed it should work with 6.10.4, but apparently it still has this problem of still missing editline. Am I doing something wrong? checking editline/readline.h usability... no checking editline/readline.h presence... no checking for editline/readline.h... no checking editline/editline.h usability... no checking editline/editline.h presence... no checking for editline/editline.h... no checking readline/readline.h usability... yes checking readline/readline.h presence... yes checking for readline/readline.h... yes checking for sign of read_history result on error... negative checking for rl_completion_matches... no checking for completion_matches... no configure: error: editline not found, so this package cannot be built See `config.log' for more details. Error: Configuring the editline-0.2.1.0 package failed make: *** [build.stamp] Error 2 - Lyle ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Unable to install Haskell Platform without editline
On Fri, Sep 11, 2009 at 12:01 PM, Judah Jacobson judah.jacob...@gmail.comwrote: The above editline requirement is for the editline C library, not the Haskell bindings: http://www.thrysoee.dk/editline My guess is that you need to install a recent version of the libedit-dev package. After installing libedit-dev, the rest of the build worked. Thanks! Now I'm having a new problem, that I'll post in another thread. - Lyle ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Haskell Platform install fails on mtl
OK, I was able to build the Haskell Platform on Ubuntu 9.04 with GHC 6.10.4. But when I try to install it, I get an error: Registering haskell-platform-2009.2.0.2... Reading package info from dist/inplace-pkg-config ... done. Writing new package config file... done. ** * Building each component completed successfully. * * Now do sudo make install ** l...@lwk-desktop:~/downloads/haskell-platform-2009.2.0.2$ sudo make install [sudo] password for lwk: scripts/install.sh Installing mtl-1.1.0.2... Error: The mtl-1.1.0.2/Setup script does not exist or cannot be run make: *** [install] Error 2 - Lyle ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: Haskell Platform install fails on mtl
It's a bug in the install.sh script. Here's the fix:
36a37,42
# Is this exact version of the package already installed?
is_pkg_installed () {
PKG_VER=$1
grep ${PKG_VER} installed.packages /dev/null 21
}
40,43c46,53
cd ${pkg} || die The directory for the component ${PKG} is missing
echo Installing ${pkg}...
install_pkg ${pkg}
cd ..
---
if is_pkg_installed ${pkg}; then
echo Platform package ${pkg} is already installed. Skipping...
else
cd ${pkg} || die The directory for the component ${PKG} is
missing
echo Installing ${pkg}...
install_pkg ${pkg}
cd ..
fi
On Fri, Sep 11, 2009 at 1:04 PM, Lyle Kopnicky li...@qseep.net wrote:
OK, I was able to build the Haskell Platform on Ubuntu 9.04 with GHC
6.10.4. But when I try to install it, I get an error:
Registering haskell-platform-2009.2.0.2...
Reading package info from dist/inplace-pkg-config ... done.
Writing new package config file... done.
**
* Building each component completed successfully.
*
* Now do sudo make install
**
l...@lwk-desktop:~/downloads/haskell-platform-2009.2.0.2$ sudo make install
[sudo] password for lwk:
scripts/install.sh
Installing mtl-1.1.0.2...
Error:
The mtl-1.1.0.2/Setup script does not exist or cannot be run
make: *** [install] Error 2
- Lyle
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[Haskell-cafe] Build 32-bit apps on 64-bit Windows?
If I am running GHC on 64-bit Windows, do I have a choice of building a 32-bit or 64-bit app? On a cursory glance through the command-line options, I didn't find anything. - Lyle ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell] The speed, size and dependability of programming languages
On Tue, Jun 2, 2009 at 1:03 PM, Paul Johnson p...@cogito.org.uk wrote: Lyle Kopnicky wrote: I think it's a combination of 1) the expressiveness measure is too simplistic, measuring number of lines alone, or counting comments, and 2) the problem set is skewed toward number-crunching, which is not (say) Prolog's strong suit. Also there is a strong tendency to optimise the code for performance rather than conciseness (concision?). In the past this tended to bloat (e.g.) Haskell entries as simple intuitive code was replaced by arrays of unboxed integers and similar C-like constructs. Well, they're supposedly measuring performance as well. If concise Haskell is non-performant, and performant Haskell is verbose, this ought to be reflected in the charts. But it managed to perform pretty well in both. I don't think Haskell got short shrift in this analysis. Perhaps other languages suffered a more written verbosely for performance problem. - Lyle ___ Haskell mailing list Haskell@haskell.org http://www.haskell.org/mailman/listinfo/haskell
Re: [Haskell] The speed, size and dependability of programming languages
Thanks for the link. I find the expressiveness results odd. How can SML/NJ be among the least expressive languages, while MLTON and OCAML are among the most expressive? How is Smalltalk less expressive than Java? Why are Prolog and Mercury among the least expressive? I think it's a combination of 1) the expressiveness measure is too simplistic, measuring number of lines alone, or counting comments, and 2) the problem set is skewed toward number-crunching, which is not (say) Prolog's strong suit. On Mon, Jun 1, 2009 at 1:18 AM, Bulat Ziganshin bulat.zigans...@gmail.comwrote: Hello haskell, Interesting blog post comparing speed and expressiveness of many languages: http://gmarceau.qc.ca/blog/2009/05/speed-size-and-dependability-of.html -- Best regards, Bulat mailto:bulat.zigans...@gmail.com ___ Haskell mailing list Haskell@haskell.org http://www.haskell.org/mailman/listinfo/haskell
[Haskell-cafe] lift in TemplateHaskell?
Hi folks, I'm having trouble reading the TemplateHaskell docs and trying to do something that seems like it should be simple. In MetaML, there is a 'lift' function which does exactly what I want to do. Here's an example function: let double n = [| 2 * $( litE (integerL n) ) |] This works as intended, but instead of writing litE (integerL n) I just want to write lift n, or something similar. I expect that would involve a type class called something like Liftable that would lift literals using the appropriate functions. Does this exist? Thanks, Lyle ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: lift in TemplateHaskell?
OK, I figured it out. The class is Language.Haskell.TH.Syntax.Lift. The function is Language.Haskell.TH.Syntax.lift. And I can rewrite my function as: let double n = [| 2 * n |] I wish this were explained in the TemplateHaskell documentation. - Lyle On Tue, Apr 14, 2009 at 2:51 PM, Lyle Kopnicky li...@qseep.net wrote: Hi folks, I'm having trouble reading the TemplateHaskell docs and trying to do something that seems like it should be simple. In MetaML, there is a 'lift' function which does exactly what I want to do. Here's an example function: let double n = [| 2 * $( litE (integerL n) ) |] This works as intended, but instead of writing litE (integerL n) I just want to write lift n, or something similar. I expect that would involve a type class called something like Liftable that would lift literals using the appropriate functions. Does this exist? Thanks, Lyle ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Missing dependency?
Hi folks, Since the time package is not included in ghc-6.10.2, I installed it via cabal. Then I tried to configure my project, and it says that the dependency is missing. Mysterious. Can anyone explain? l...@lwk-desktop:~/devel/vintage-basic$ ghc-pkg list /usr/local/lib/ghc-6.10.2/./package.conf: Cabal-1.6.0.3, HUnit-1.2.0.3, QuickCheck-1.2.0.0, array-0.2.0.0, base-3.0.3.1, base-4.1.0.0, bytestring-0.9.1.4, containers-0.2.0.1, directory-1.0.0.3, (dph-base-0.3), (dph-par-0.3), (dph-prim-interface-0.3), (dph-prim-par-0.3), (dph-prim-seq-0.3), (dph-seq-0.3), editline-0.2.1.0, filepath-1.1.0.2, (ghc-6.10.2), ghc-prim-0.1.0.0, haddock-2.4.2, haskell-src-1.0.1.3, haskell98-1.0.1.0, hpc-0.5.0.3, html-1.0.1.2, integer-0.1.0.1, mtl-1.1.0.2, network-2.2.1, old-locale-1.0.0.1, old-time-1.0.0.2, packedstring-0.1.0.1, parallel-1.1.0.1, parsec-2.1.0.1, pretty-1.0.1.0, process-1.0.1.1, random-1.0.0.1, regex-base-0.72.0.2, regex-compat-0.71.0.1, regex-posix-0.72.0.3, rts-1.0, stm-2.1.1.2, syb-0.1.0.1, template-haskell-2.3.0.1, unix-2.3.2.0, xhtml-3000.2.0.1 /home/lwk/.ghc/i386-linux-6.10.2/package.conf: HTTP-4000.0.4, time-1.1.2.3, zlib-0.5.0.0 l...@lwk-desktop:~/devel/vintage-basic$ runhaskell Setup.hs configure Configuring vintage-basic-1.0.1... Setup.hs: At least the following dependencies are missing: time =1.1 l...@lwk-desktop:~/devel/vintage-basic$ Thanks, Lyle ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell] ANNOUNCE: GHC version 6.10.2
Great! But what happened to the time package? It was in 6.10.1. Has it been intentionally excluded from 6.10.2? On Wed, Apr 1, 2009 at 1:21 PM, Ian Lynagh ig...@earth.li wrote: == The (Interactive) Glasgow Haskell Compiler -- version 6.10.2 == The GHC Team is pleased to announce a new patchlevel release of GHC. This release contains a number of bugfixes relative to 6.10.1, including some performance fixes, so we recommend upgrading. Release notes are here: http://haskell.org/ghc/docs/6.10.2/html/users_guide/release-6-10-2.html ___ Haskell mailing list Haskell@haskell.org http://www.haskell.org/mailman/listinfo/haskell
Re: [jhc] Re: [Haskell] ANNOUNCE: jhc 0.6.0 Haskell Compiler
Those are impressive results. Typically on programming language benchmarks, the speed of ghc-generated code fares well against C, sometimes outperforming it, at best being 20x faster, at worst being 3x slower. Since it already seems fast enough, I'm astonished that jhc could make it even faster. http://shootout.alioth.debian.org/u32q/benchmark.php?test=alllang=ghclang2=gccbox=1 Where ghc-generated code fares poorly against other languages is memory usage. Has there been an effort in jhc to reduce the memory footprint of generated code? How does it fare against ghc in this area? Thanks, Lyle On Mon, Mar 23, 2009 at 1:09 AM, John Meacham j...@repetae.net wrote: On Mon, Mar 23, 2009 at 08:40:02AM +0100, Ketil Malde wrote: I had done that, actually, before even my first post, and knew that it changes little to the picture, at least on my system. I think Bulat was right on the money here: you're essentially testing the efficiency of writing integers. Presumably, JHC is better than GHC at specializing/inlining this library function. Indeed, but isn't being better at specializing/inlining exactly what an optimizing compiler should do. :) In any case, these results are not atypical, generally, if jhc can compile something, it ends up being 2-3x faster than ghc. After all, C-comparable (or even superior) speed is the main goal of jhc development. And if anything, I am more convinced than when I started that the goal is achievable. With jhc today, C comparable performance from numerical code is not difficult to achieve with some attention to strictness annotations. John -- John Meacham - ⑆repetae.net⑆john⑈ ___ Haskell mailing list Haskell@haskell.org http://www.haskell.org/mailman/listinfo/haskell ___ Haskell mailing list Haskell@haskell.org http://www.haskell.org/mailman/listinfo/haskell
Re: [Haskell-cafe] ANNOUNCE: Vintage BASIC 1.0
I've posted a new version, 1.0.1, that has a usage message if you run it with no arguments. There is a package for Windows now (not just a binary) as well as Linux. Both packages include documentation and example programs. Thanks for pointing that out! On Fri, Mar 13, 2009 at 1:31 AM, Wolfgang Jeltsch jelt...@informatik.tu-cottbus.de wrote: When running the executable, nothing happens. The executable should show a usage message instead. Where are the BASIC programs? I think, you have to grab them from the source. They should be installed, too. Best wishes, Wolfgang ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ANNOUNCE: Vintage BASIC 1.0
On Fri, Mar 13, 2009 at 1:31 AM, Wolfgang Jeltsch jelt...@informatik.tu-cottbus.de wrote: When running the executable, nothing happens. The executable should show a usage message instead. Where are the BASIC programs? I think, you have to grab them from the source. They should be installed, too. Thanks for your feedback, and for checking out Vintage BASIC! I will add a usage message, as you suggested. Currently the usage is only described in the User's Guide. There are no options; you just give it the name of one or more BASIC source files. (Naturally this extends to doing nothing when supplied with zero source files.) The BASIC games are at http://www.vintage-basic.net/games.html. There is a tarball of all the games (bcg.tar.gzhttp://www.vintage-basic.net/downloads/bcg.tar.gz) as well. These are separated from the Vintage BASIC distribution for legal reasons. Vintage BASIC is copyrighted by me under a BSD license. The games were written by many authors and compiled into a book copyrighted by Creative Computing. I have secured permission from the editor to post the games. I do not wish to imply that they are covered by the same license as the interpreter. If anyone has any suggestions as to how to make the process simpler, I'd be happy to hear it. Thanks, Lyle P.S. I need to get my other e-mail account subscribed to this list ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] ANNOUNCE: Vintage BASIC 1.0
I am pleased to announce the initial release of Vintage BASIC, an interpreter for microcomputer-era BASIC. Fully unit-tested, it faithfully implements the common elements of the language. On the web site, you can find 102 games from the classic book BASIC Computer Games, all of which run flawlessly. Have fun! This is a standalone interpreter, operating on text files. Although not an embedding, like Lennart Augustsson's clever implementation, it does use a custom BASIC monad in order to execute the code. A unique feature of this implementation is that control structures such as FOR are implemented using resumable exceptions: FOR is a handler and NEXT throws an exception. A Developer's Guide is included with the source. This is my first public release of open source software. I have been working on this project since 2003. Home page: http://www.vintage-basic.net Also available on Hackagehttp://hackage.haskell.org/cgi-bin/hackage-scripts/package/vintage-basicand patch-tag.com http://patch-tag.com/repo/vintage-basic/home. Please e-mail me at l...@vintage-basic.net with any questions/comments. - Lyle ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Distributing Linux binaries
Thanks, folks. I have decided for now just to release a tarball with an executable and some docs, that can be expanded where the user deems appropriate. I'll try a static link if people are having problems with it. - Lyle ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Distributing Linux binaries
Thanks folks for your replies. I did learn, from your e-mails and from the cabal documentation (example 9 on page http://www.haskell.org/cabal/release/cabal-latest/doc/users-guide/builders.htm), how to build a tarball with an executable and LICENSE file, via cabal copy. It would have been nice to include the documentation (user's guide) as well, but I don't know how to get cabal copy to put that into the bundle. Unfortunately, I don't feel it's of great use to the end user. Now they have a tarball with paths like /usr/local/bin/vintbas and /usr/local/share/doc/vintage-basic-1.0/LICENSE.txt. Untarring it gives a warning and strips the leading /, so it won't untar in root unless you CD to root first. And of course you have to have root access to do that. If you want to install it in your user dir, you'll have to make a substitution for the paths. You suggested I write my own install script. But certainly this is a common situation, and someone has made a generic install script for this sort of thing? As I've said I tried to make a Debian package, folowing two different cabal-to-debian instructions, and neither one worked. If it is a hurdle for me, I can imagine a lot of people are getting frustrated at trying to distribute their binaries on Linux. - Lyle ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Distributing Linux binaries
Hi folks, I've got an application to release. I'm releasing the source, but I also wanted to release binary versions for people that don't have GHC. I developed on Windows, so making a Windows executable was simple. I also have access to an Ubuntu Linux box, on which I can easily build and test my app. But, I'm a bit confused about how to release binaries for Linux. It's not so simple as on Windows. Or, maybe it is but I don't know it. What do people recommend as a way of distributing Linux binaries? I tried to make a Debian package and couldn't figure it out, but maybe that's overkill. GHC itself has some kind of tarball for the binary distributions, one for Debian and one for Red Hat. How would I make such a package and what would go into it? There's only one executable, so it shouldn't be too complicated. I figure the main issue on Linux is that when you compile it, it's linked to specific shared libraries. Don't have a Mac myself but I'm happy to have Mac folks submit binaries. I'll worry about that later. - Lyle ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Haskell Fest
Looks like a lot of fun! http://www.haskellchamber.com/page6.html ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] GHC 6.11 missing time package?
OK, I was able to get it to build. I just had to install MinGW and put its bin directory in my path. Thanks for the help! (Actually, I ended up building time-1.1.2.3 for 6.10.1.20090110.) On Sun, Feb 1, 2009 at 2:38 AM, Krzysztof Skrzętnicki gte...@gmail.comwrote: It looks that you need MSYS or Cygwin to complete this build. Here you can find instructions regarding MSYS (and also GLUT, but you can ignore that part): http://www.haskell.org/pipermail/haskell-cafe/2007-September/031535.html All best Christopher Skrzętnicki 2009/2/1 Lyle Kopnicky li...@qseep.net I tried building it from hackage. I got an error: Setup.hs: sh: createProcess: does not exist (No such file or directory) ...which is very similar to the error I get if I try to build it using 6.10: Setup.hs: sh: runGenProcess: does not exist (No such file or directory) I don't know if there's something wrong with the package, or I don't have something set up right to build it on Windows. On Sat, Jan 31, 2009 at 10:13 PM, Antoine Latter aslat...@gmail.comwrote: 2009/1/31 Lyle Kopnicky li...@qseep.net: Hi folks, I'm getting ready to release a piece of software. Unfortunately due to a bug in GHC 6.10 on Windows it does not handle Ctrl+C properly. Since the bug has been fixed (thank you Simon Marlow), I figured I'd download a 6.11 build (I grabbed the 2009-01-29 version). Unfortunately, my project won't build with it because it's missing the time-1.1 package. This is sad because I had gone through the trouble to rewrite my use of oldtime to use time, thinking it was more future-proof. Is this an oversight in the nightly build, or is this package going out of GHC? Thanks, Lyle Hackage seems to have it: http://hackage.haskell.org/cgi-bin/hackage-scripts/package/time Does that work? -Antoine ___ 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] GHC 6.11 missing time package?
I tried building it from hackage. I got an error: Setup.hs: sh: createProcess: does not exist (No such file or directory) ...which is very similar to the error I get if I try to build it using 6.10: Setup.hs: sh: runGenProcess: does not exist (No such file or directory) I don't know if there's something wrong with the package, or I don't have something set up right to build it on Windows. On Sat, Jan 31, 2009 at 10:13 PM, Antoine Latter aslat...@gmail.com wrote: 2009/1/31 Lyle Kopnicky li...@qseep.net: Hi folks, I'm getting ready to release a piece of software. Unfortunately due to a bug in GHC 6.10 on Windows it does not handle Ctrl+C properly. Since the bug has been fixed (thank you Simon Marlow), I figured I'd download a 6.11 build (I grabbed the 2009-01-29 version). Unfortunately, my project won't build with it because it's missing the time-1.1 package. This is sad because I had gone through the trouble to rewrite my use of oldtime to use time, thinking it was more future-proof. Is this an oversight in the nightly build, or is this package going out of GHC? Thanks, Lyle Hackage seems to have it: http://hackage.haskell.org/cgi-bin/hackage-scripts/package/time Does that work? -Antoine ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] GHC 6.11 missing time package?
Hi folks, I'm getting ready to release a piece of software. Unfortunately due to a bug in GHC 6.10 on Windows it does not handle Ctrl+C properly. Since the bug has been fixed (thank you Simon Marlow), I figured I'd download a 6.11 build (I grabbed the 2009-01-29 version). Unfortunately, my project won't build with it because it's missing the time-1.1 package. This is sad because I had gone through the trouble to rewrite my use of oldtime to use time, thinking it was more future-proof. Is this an oversight in the nightly build, or is this package going out of GHC? Thanks, Lyle ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] How does one use Text.Regex.Base.RegexLike?
I'm trying to migrate code from using the old Text.Regex to the new Text.Regex.Base. But, I'm getting type errors. I can't even create a regex. Looking at the docs, it seems like this should print bcd: import Data.Array import Text.Regex.Base import Text.Regex.Posix rx = makeRegex a(.*)A Just (_, mt, _) = matchOnceText rx abcdA main = putStrLn (fst (mt ! 0)) But I get an error: src\regex.hs:5:5: No instance for (RegexMaker regex compOpt execOpt [Char]) arising from a use of `makeRegex' at src\regex.hs:5:5-22 Possible fix: add an instance declaration for (RegexMaker regex compOpt execOpt [Char]) In the expression: makeRegex a(.*)A In the definition of `rx': rx = makeRegex a(.*)A src\regex.hs:7:18: No instance for (RegexLike regex [Char]) arising from a use of `matchOnceText' at src\regex.hs:7:18-41 Possible fix: add an instance declaration for (RegexLike regex [Char]) In the expression: matchOnceText rx abcdA In a pattern binding: Just (_, mt, _) = matchOnceText rx abcdA Why does it say there is no instance? Isn't the instance imported by Text.Regex.Posix? Why in the world is it so complicated just to get a matched substring out of the text? Is there an easier way? Thanks, Lyle ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] How does one use Text.Regex.Base.RegexLike?
Yes, sort of. It enables me to get some simple examples working with (=~). But I still don't know how to get makeRegex to work. You need it to specify options like case insensitivity, or to use functions like matchAllText. On Tue, Dec 23, 2008 at 11:29 AM, Jeremy Shaw jer...@n-heptane.com wrote: Hello, Does this help? http://www.serpentine.com/blog/2007/02/27/a-haskell-regular-expression-tutorial/ j. At Tue, 23 Dec 2008 11:21:41 -0800, Lyle Kopnicky wrote: [1 multipart/alternative (7bit)] [1.1 text/plain; ISO-8859-1 (7bit)] I'm trying to migrate code from using the old Text.Regex to the new Text.Regex.Base. But, I'm getting type errors. I can't even create a regex. Looking at the docs, it seems like this should print bcd: import Data.Array import Text.Regex.Base import Text.Regex.Posix rx = makeRegex a(.*)A Just (_, mt, _) = matchOnceText rx abcdA main = putStrLn (fst (mt ! 0)) But I get an error: src\regex.hs:5:5: No instance for (RegexMaker regex compOpt execOpt [Char]) arising from a use of `makeRegex' at src\regex.hs:5:5-22 Possible fix: add an instance declaration for (RegexMaker regex compOpt execOpt [Char]) In the expression: makeRegex a(.*)A In the definition of `rx': rx = makeRegex a(.*)A src\regex.hs:7:18: No instance for (RegexLike regex [Char]) arising from a use of `matchOnceText' at src\regex.hs:7:18-41 Possible fix: add an instance declaration for (RegexLike regex [Char]) In the expression: matchOnceText rx abcdA In a pattern binding: Just (_, mt, _) = matchOnceText rx abcdA Why does it say there is no instance? Isn't the instance imported by Text.Regex.Posix? Why in the world is it so complicated just to get a matched substring out of the text? Is there an easier way? Thanks, Lyle [1.2 text/html; ISO-8859-1 (7bit)] [2 text/plain; us-ascii (7bit)] ___ 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] How does one use Text.Regex.Base.RegexLike?
Yes, that worked, thanks. I just figured that out too. Here's a whole working program: import Text.Regex.Base import Text.Regex.Posix rx :: Regex rx = makeRegex a(.*)A mr = match rx abcdA text = head $ mrSubList mr main = putStrLn text On Tue, Dec 23, 2008 at 12:30 PM, Daniel Fischer daniel.is.fisc...@web.dewrote: Am Dienstag, 23. Dezember 2008 21:09 schrieb Lyle Kopnicky: Yes, sort of. It enables me to get some simple examples working with (=~). But I still don't know how to get makeRegex to work. You need it to specify options like case insensitivity, or to use functions like matchAllText. Your problem is that GHC can't know which instance to choose. You can help it by giving a type signature, e.g. rx :: Regex rx = makeRegex a(.*)A HTH, Daniel ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: TimeDiff to Int?
Thanks, but that doesn't seem to work. I got an answer of -3. I tried it again a minute later and it was still -3. I tried again a minute later and it was -1. It's just after 9am here, so I have no idea what to make of those numbers. I have settled on this code: secondsSinceMidnight :: IO Int secondsSinceMidnight = do zonedTime - getZonedTime return $ floor $ toRational $ timeOfDayToTime $ localTimeOfDay $ zonedTimeToLocalTime zonedTime On Thu, Nov 13, 2008 at 2:29 AM, Jon Fairbairn [EMAIL PROTECTED]wrote: Lyle Kopnicky [EMAIL PROTECTED] writes: I had some code using the oldtime package, and want to convert it to use the time package. One of the things I need to do is calculate the number of seconds since midnight. The easy part is getting a TimeDiff result: You mean DiffTime? utc - getCurrentTime tz - getCurrentTimeZone let td = timeOfDayToTime $ localTimeOfDay $ utcToLocalTime tz utc Now td is a TimeDiff representation of the number of seconds since midnight. It prints nicely, but I'm having a heck of a time figuring out how to truncate it to an Int. You could do something like fromEnum td `div` fromEnum (secondsToDiffTime 1) which says that you are computing a whole number of seconds. -- Jón Fairbairn [EMAIL PROTECTED] http://www.chaos.org.uk/~jf/Stuff-I-dont-want.html (updated 2008-04-26) ___ 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] TimeDiff to Int?
Hi folks, I had some code using the oldtime package, and want to convert it to use the time package. One of the things I need to do is calculate the number of seconds since midnight. The easy part is getting a TimeDiff result: utc - getCurrentTime tz - getCurrentTimeZone let td = timeOfDayToTime $ localTimeOfDay $ utcToLocalTime tz utc Now td is a TimeDiff representation of the number of seconds since midnight. It prints nicely, but I'm having a heck of a time figuring out how to truncate it to an Int. The floor function is only supported by the RealFrac class. Although TimeDiff has an instance of RealFrac and Fractional, it doesn't have an instance of RealFrac. I looked up the various to* and from* functions and have come up short. fromEnum yields an Int but it's the wrong value. I know I could use show and then use readS to get an Integer, or use formatTime (and reparse that), but that's a hack. I can convert it to a TimeOfDay which gives me hours, minutes, and seconds, but then I have to do arithmetic on it, and the seconds are of type Pico, which I can't call floor on either. I can convert it to a Rational via timeOfDayToDayFraction, but a TimeDiff is already a Rational those don't have floor. What am I missing? There has got to be an easy way to count seconds! Thanks, Lyle ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] TimeDiff to Int?
Thanks Philip and Roger, I think I'll use... floor $ toRational td ...although I could have sworn that didn't work last night. I don't see that TimeDiff has an instance of RealFrac, where floor is defined, though it does have a instances of Real and Fractional. Yes, the numeric classes are a bit hard to follow. Especially confusing is the conversions. I'm thinking of making a multiparameter Coercible class, with a coerce function, to help address that. - Lyle On Wed, Nov 12, 2008 at 9:43 AM, Philip Weaver [EMAIL PROTECTED]wrote: 2008/11/12 Lyle Kopnicky [EMAIL PROTECTED] Hi folks, I had some code using the oldtime package, and want to convert it to use the time package. One of the things I need to do is calculate the number of seconds since midnight. The easy part is getting a TimeDiff result: utc - getCurrentTime tz - getCurrentTimeZone let td = timeOfDayToTime $ localTimeOfDay $ utcToLocalTime tz utc Now td is a TimeDiff representation of the number of seconds since midnight. It prints nicely, but I'm having a heck of a time figuring out how to truncate it to an Int. The floor function is only supported by the RealFrac class. Although TimeDiff has an instance of RealFrac and Fractional, it doesn't have an instance of RealFrac. I looked up the various to* and from* functions and have come up short. fromEnum yields an Int but it's the wrong value. I know I could use show and then use readS to get an Integer, or use formatTime (and reparse that), but that's a hack. I can convert it to a TimeOfDay which gives me hours, minutes, and seconds, but then I have to do arithmetic on it, and the seconds are of type Pico, which I can't call floor on either. I can convert it to a Rational via timeOfDayToDayFraction, but a TimeDiff is already a Rational those don't have floor. What am I missing? There has got to be an easy way to count seconds! Well, you could always (read . takeWhile (not . (=='.')) . show), but here's a better way: let x = toRational td in numerator x `div` denominator x This was just the first thing I could come up with. I bet there's a nicer way. - Phil Thanks, Lyle ___ 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] getLine and ^C on Windows
Hi folks, I'm using System.IO.getLine to read input in my program. I've compiled it on Windows Vista with ghc-6.10.1. I've noticed that if I press Ctrl+C while the program is waiting for input, it will get stuck. No keypresses can get me out of the program - I have to kill the shell. I've tried cmd.exe, Powershell and cygwin - same behavior. I'm sure editline would work better, but it's overkill. I just want to read lines of text and don't need fancy edit behavior. And I think editline complicates the build process. I also want my program to work right in non-interactive mode, reading redirected input. Am I missing something? Thanks, Lyle ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] vector vs uvector
stefan kersten wrote: hi, what's the difference between the vector [1] and uvector [2] packages? should one of those preferred over the other? thanks, sk [1] http://hackage.haskell.org/cgi-bin/hackage-scripts/package/vector-0.1 [2] http://hackage.haskell.org/cgi-bin/hackage-scripts/package/uvector-0.1.0.1 You should use the most mature and stable package, which is of course, uvector, being a whole 0.0.0.1 versions past vector. ;) - Lyle ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] uvector and the stream interface
Don Stewart wrote: Yes, we have long been discussing a generic Stream library to which the various sequence structures can be translated to and from. Already it is useful to say, stream bytestrings into uvectors and out to lists. Isn't there already such a thing? http://www.haskell.org/haskellwiki/Library/Streams - Lyle ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Poor Parsec error message
Hi folks, I'm using Parsec to parse a stream of tokens. The token primitive takes, among other arguments, a function to print tokens. However, this function is not always applied. Try the code below: - import Text.ParserCombinators.Parsec import Text.ParserCombinators.Parsec.Pos(newPos) mytoken :: (Eq t, Show t) = t - GenParser (SourcePos,t) () t mytoken x = token showTok posFromTok testTok where showTok (pos,t) = ++ show t ++ posFromTok (pos,t) = pos testTok (pos,t) = if (x == t) then Just t else Nothing main = do putStrLn case parse the123Parser [(newPos 1 n, n) | n - [1,2,3,4]] of (Left err) - putStrLn (show err) (Right _) - putStrLn parsed correctly putStrLn case parse the123Parser [(newPos 1 n, n) | n - [1,3,4]] of (Left err) - putStrLn (show err) (Right _) - putStrLn parsed correctly the123Parser = do mytoken 1 mytoken 2 mytoken 3 eof return 123 --- The output I get looks like this: (line 1, column 4): unexpected [((line 1, column 4),4)] expecting end of input (line 1, column 3): unexpected 3 In the second parse case, it correctly uses my showTok function to show the token. But in the first case, it just uses the regular show method. I guess that's because the eof parser doesn't know anything about how to show the token it sees. Any ideas on how I can get the error message in the first case to look more like the second case? Thanks, Lyle ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Poor Parsec error message
I figured it out, but it's not pretty. The problem is that the eof
parser had no awareness of the showTok function. To fix the problem, I
had to replace eof with its definition in terms of notFollowedBy, then
replace notFollowedBy with its definition in terms of try and
unexpected. Then, I changed the show [c] into showToken c.
Passing a token shower to the token function isn't a very robust way of
guaranteeing your tokens display properly in error messages, because the
other combinators don't take the same option. Of course, you can
implement a Show instance for your tokens as you like. But, if you make
the Show instance show the pretty version for the user, you lose the
ability to see the real structure you get from a derived Show instance.
In my real code, I want debugging to show tokens using a derived Show
instance, so I can see all the structure. But when I show them to the
user, I don't want them to see the embedded SourcePos, or the
constructor names - I just want them to see a representation of what was
lexed in order to produce that token.
I think there should be a class called Token, with a method called
showToken, or unlex, or display, or displayInError, something like that.
This class should be a precondition of all the GenParser combinators. It
should use the provided method to show the token in error messages.
Here's the working version:
import Text.ParserCombinators.Parsec
import Text.ParserCombinators.Parsec.Pos(newPos)
showToken (pos,t) = ++ show t ++
myToken :: (Eq t, Show t) = (t - Bool) - GenParser (SourcePos,t) ()
(SourcePos,t)
myToken q = token showToken posFromTok testTok where
posFromTok (pos,t) = pos
testTok (pos,t) = if (q t) then Just (pos,t) else Nothing
main = do
putStrLn
case parse the123Parser [(newPos 1 n, n) | n - [1,2,3,4]] of
(Left err) - putStrLn (show err)
(Right _) - putStrLn parsed correctly
putStrLn
case parse the123Parser [(newPos 1 n, n) | n - [1,3,4]] of
(Left err) - putStrLn (show err)
(Right _) - putStrLn parsed correctly
the123Parser = do
myToken (==1)
myToken (==2)
myToken (==3)
try (do{ c - myToken (const True); unexpected (showToken c) } |
return ())
notFollowedBy (myToken (==4))
return 123
- Lyle
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Re: [Haskell-cafe] Aim Of Haskell
Taral wrote: On 12/11/06, Nia Rium [EMAIL PROTECTED] wrote: In my humble opinion, in this context, GUI doesn't mean a library to implement a GUI application. It rather means an interpreter/compiler that provides graphical interface. Windows users can use Visual Haskell... It's still in an early development phase. - Lyle ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Why so slow?
The code below is using way more RAM than it should. It seems to only
take so long when I build the 'programs' list - the actual
reading/parsing is fast. For a 5MB input file, it's using 50MB of RAM!
Any idea how to combat this?
Thanks,
Lyle
{-# OPTIONS_GHC -fglasgow-exts #-}
-- linear_importer.hs
import Control.Monad (unless)
import Data.ByteString.Char8 (ByteString)
import qualified Data.ByteString.Char8 as BS
import Text.Regex as RE
import Data.Time.Calendar
import Data.Time.LocalTime
import System.Environment
-- Consider adding strictness as necessary for performance.
-- STB time channel
data ChannelChange = ChannelChange Int LocalTime Int
deriving Show
-- channel program_no start
end network_no
data ScheduleProgram = ScheduleProgram Int IntLocalTime
LocalTime (Maybe Int)
deriving Show
main = do
fileNames - getArgs
ensure (length fileNames == 2) usageMessage
let [eventFileName,programFileName] = fileNames
putStrLn (Reading program schedule file from ' ++ programFileName
++ '...)
text - BS.readFile programFileName
programs - sequence $ map parseScheduleProgram (BS.lines text)
print (take 20 programs)
return ()
usageMessage = Usage: linear_importer channel change file schedule
file
parseScheduleProgram :: ByteString - IO ScheduleProgram
parseScheduleProgram s = do
let fields = BS.split '|' s
ensure (length fields == 7) (Wrong number of fields in schedule
program: ++ BS.unpack s)
let
[_,channelNoText,programNoText,_,startTimeText,endTimeText,networkNoText]
= fields
let channelNo = read $ BS.unpack channelNoText
programNo = read $ BS.unpack programNoText
startTime - parseProgramTime startTimeText
endTime - parseProgramTime endTimeText
let networkNo = if BS.null networkNoText then Nothing else Just
(read (BS.unpack networkNoText))
return $ ScheduleProgram channelNo programNo startTime endTime networkNo
parseProgramTime :: ByteString - IO LocalTime
parseProgramTime s = do
let parts = BS.split 'T' s
ensure (length parts == 2)
(Expected exactly one T in eventChannelChange time: ++
BS.unpack s)
let [datePart,timePart] = parts
ensure (BS.length datePart == 8)
(Expected 8 digits in date part of eventChannelChange time:
++ BS.unpack s)
let (yearPart, monthDayPart) = BS.splitAt 4 datePart
(monthPart, dayPart) = BS.splitAt 2 monthDayPart
year = read $ BS.unpack yearPart
month = read $ BS.unpack monthPart
day = read $ BS.unpack dayPart
let date = fromGregorian year month day
ensure (BS.length timePart == 6)
(Expected 6 digits in time part of eventChannelChange time:
++ BS.unpack s)
let (hoursPart,minutesSecondsPart) = BS.splitAt 2 timePart
(minutesPart,secondsPart) = BS.splitAt 2 minutesSecondsPart
hours = read $ BS.unpack hoursPart
minutes = read $ BS.unpack minutesPart
seconds = read $ BS.unpack secondsPart
let time = TimeOfDay hours minutes (fromInteger seconds)
return (LocalTime date time)
ensure :: Bool - String - IO ()
ensure x s = unless x $ ioError (userError s)
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[Haskell] Re: Streams 0.1 ported to GHC 6.6
Bulat Ziganshin wrote: Hello Lyle and all, i'm glad to inform you that Stream 0.1 library is now compatible with just released GHC 6.6. please download new version as http://www.haskell.org/library/Streams.tar.gz this archive contains file Streams.cabal.6.6 that is cabal file developed specially for new GHC. if you use ghc 6.6, just rename it to Streams.cabal and then build library as usual Following the instructions above, I'm still getting the following error when building Streams: [16 of 21] Compiling Data.AltBinary.Class ( Data/AltBinary/Class.hs, dist/build/Data/AltBinary/Class.o ) Data/AltBinary/Class.hs:526:0: Parse error in pattern make: *** [build] Error 1 l - Lyle ___ Haskell mailing list Haskell@haskell.org http://www.haskell.org/mailman/listinfo/haskell
[Haskell-cafe] Multiple stages in Template Haskell
Hi folks, I noticed that in Template Haskell, you can only have one level of splicing or quasi-quoting. E.g., you can't write: $(zipN ($(sel 2 3) (zip level,3,( ['a'..'Z'] [1..] (words now is the time) Because you can't have a splice inside a splice. But wouldn't it be handy to use all these macros when defining other macros? This would be like stages in MetaML, which have no such limitation. But all the stages but the last one would be evaluated at compile time. The compiler would look for the deepest level of nested splices and evaluate it first. On the other hand, I can understand why you wouldn't include splices and quasi-quotes in the Language.Haskell.TH.Syntax - programmers could write functions that dynamically created arbitrarily (even infinitely) nested splices - so it would be undecidable where to start. I'm wondering if there's some reason this restriction is imposed. Is it particularly difficult to implement, or are there more theoretical problems? Does that mean I'm volunteering? ;) - Lyle ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Error building Edison 1.2.0.1
Robert Dockins wrote: On Thursday 05 October 2006 16:51, Lyle Kopnicky wrote: Robert Dockins wrote: mtl is the Monad Transformer Library. It's a part of the standard libraries in 6.4.x. There's been a good deal of chatter recently about reducing the set of libraries the GHC ships with; it may be that mtl is on that list. I haven't really been following, so I'm not sure. Maybe there's something broken in this GHC snapshot. I've already noticed Template Haskell seems to be broken in it. Possible. I also notice that QuickCheck isn't in your list of installed packages. You'll need that to compile edison-core. OK, now I've uninstalled GHC 6.5.x, and installed 6.4.2, and now I can compile Edison without any problem. I think that 6.5.x snapshot was missing some libraries. Three cheers for stable releases. - Lyle ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Error building Edison 1.2.0.1
Robert Dockins wrote: On Wednesday 04 October 2006 16:16, Lyle Kopnicky wrote: Robert Dockins wrote: Whats the output of ghc-pkg -l ? [EMAIL PROTECTED]:~$ ghc-pkg -l /usr/local/lib/ghc-6.5.20060924/package.conf: Cabal-1.1.4, base-2.0, (ghc-6.5.20060924), haskell98-1.0, parsec-2.0, readline-1.0, regex-base-0.71, regex-compat-0.71, regex-posix-0.71, rts-1.0, stm-2.0, template-haskell-2.0, unix-1.0 l Hummm. Well, I confess that I'm confused. Cabal 1.1.4 should work, because that's what I have on my machines; I've just tested it here. The only thing I can think of is that the 'runhaskell' command is still bound to your old GHC, or to something else (Hugs maybe?). If that's the case, you can edit the makefile and set the 'RUNHS' variable in the first line to the full path to your 6.5 runghc. Or you can edit the .cabal files as suggested above. I don't have hugs installed, and I've uninstalled ghc 6.4.1, so it can only be running 6.5. I've pasted the error in again here for reference: [EMAIL PROTECTED]:~/devel/edison-1.2.0.1-source$ sudo make system Password: cd edison-api \ runhaskell Setup.hs configure \ runhaskell Setup.hs build \ runhaskell Setup.hs install Configuring EdisonAPI-1.2... configure: Dependency base=1.0: using base-2.0 configure: Dependency haskell98=1.0: using haskell98-1.0 Setup.hs: cannot satisfy dependency mtl=1.0 make: *** [api-system] Error 1 [EMAIL PROTECTED]:~/devel/edison-1.2.0.1-source$ Do you know what mtl is? Maybe there's something broken in this GHC snapshot. I've already noticed Template Haskell seems to be broken in it. - Lyle ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Error building Edison 1.2.0.1
Robert Dockins wrote: On Tuesday 03 October 2006 22:58, Lyle Kopnicky wrote: Robert Dockins wrote: On Tuesday 03 October 2006 22:00, Lyle Kopnicky wrote: Hi folks, I tried to build edison-1.2.0.1-sources with the command 'make system' but got: *** Exception: Line 10: Unknown field 'hs-source-dirs' I am using GHC 6.4.1. Any idea how to fix this? You are probably using an older version of Cabal. You can either upgrade Cabal or, from the Edison README*: This version of edison builds correctly with Cabal version 1.1.4, which is shipped with GHC 6.4.2. To build on earlier versions, it should suffice to: s/UndecidableInstances/AllowUndecidableInstances/ s/Hs-Source-Dirs:/Hs-Source-Dir:/ in the .cabal files. The 'hs-source-dir' cabal directive was depreciated in 1.1.4, but perhaps I should have waited a bit longer to change it. OTOH, there isn't any good way to deal with the change in the undecidable instances flag, since it was outright changed. G. *grumble* incompatible changes in minor releases *grumble*. (*) Further, g... in the above, I've fixed several embarrasing typos in the text of the README. Oh, OK, thanks! Well, now I'm running GHC 6.5.20060924, and getting the error mentioned in my previous message. Whats the output of ghc-pkg -l ? [EMAIL PROTECTED]:~$ ghc-pkg -l /usr/local/lib/ghc-6.5.20060924/package.conf: Cabal-1.1.4, base-2.0, (ghc-6.5.20060924), haskell98-1.0, parsec-2.0, readline-1.0, regex-base-0.71, regex-compat-0.71, regex-posix-0.71, rts-1.0, stm-2.0, template-haskell-2.0, unix-1.0 l ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Error building Edison 1.2.0.1
Hi folks, I tried to build edison-1.2.0.1-sources with the command 'make system' but got: *** Exception: Line 10: Unknown field 'hs-source-dirs' I am using GHC 6.4.1. Any idea how to fix this? Thanks, Lyle ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Error building Edison 1.2.0.1
Robert Dockins wrote: On Tuesday 03 October 2006 22:00, Lyle Kopnicky wrote: Hi folks, I tried to build edison-1.2.0.1-sources with the command 'make system' but got: *** Exception: Line 10: Unknown field 'hs-source-dirs' I am using GHC 6.4.1. Any idea how to fix this? You are probably using an older version of Cabal. You can either upgrade Cabal or, from the Edison README*: This version of edison builds correctly with Cabal version 1.1.4, which is shipped with GHC 6.4.2. To build on earlier versions, it should suffice to: s/UndecidableInstances/AllowUndecidableInstances/ s/Hs-Source-Dirs:/Hs-Source-Dir:/ in the .cabal files. The 'hs-source-dir' cabal directive was depreciated in 1.1.4, but perhaps I should have waited a bit longer to change it. OTOH, there isn't any good way to deal with the change in the undecidable instances flag, since it was outright changed. G. *grumble* incompatible changes in minor releases *grumble*. (*) Further, g... in the above, I've fixed several embarrasing typos in the text of the README. Oh, OK, thanks! Well, now I'm running GHC 6.5.20060924, and getting the error mentioned in my previous message. - Lyle ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Optimizing a title matcher
Ketil Malde wrote: Do you really need that to search for movie titles? At any rate, an exact-match finite-map implementation is a good start - to get good performance, you probably will need to use some kind of index to reduce the amount of data to search exhaustively (all-against-all). For text searching I think it is effective to use an index that maps from words (so that looking up a word gives you all the movies with that word in the title). Gotcha. That's exactly the approach I've switched to. It is possible to miss titles, if words are misspelled, but it's unlikely that all words in the title will be misspelled, so you can at least narrow your search to titles that have at least one matching (non-trivial) word. - Lyle ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: Getting the latest
Max Vasin wrote: Lyle I have no idea how it decides where to go. Right now ghc Lyle 6.4.1 is in /usr/local/bin/ghc. After I 'make install', will it Lyle be ghc 6.5? I don't want to screw up the installed package so it Lyle can't be updated later. It should be :-) It should be screwed up? Or it should be updated later? Ideally I'd like to keep the Ubuntu package where it is. I'd like to install the experimental GHC in a different place. Then I want to change my path to point to the experimental one for building. PS: It is better to build a custom package (dh_make will help you). I don't have a command called dh_make. I do have some other dh_* commands. What do I need to run dh_make? Where can I find documentation? Thanks, Lyle ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Unable to profile program using Data.ByteString.Lazy
Donald Bruce Stewart wrote: You're cabal version is too old then. Try updating either Cabal or GHC. -- Don It's the latest version (6.4.1) packaged for Ubuntu. I'll have to download and install a newer version manually. Unfortunately, the download site seems to be down again :( - Lyle ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Optimizing a title matcher
Hi folks,
I'm competing in a contest at work, and we're allowed to use whatever
language we want. I decided this was my chance to prove to people that
Haskell was up to the challenge. Unfortunately, I ran into performance
problems. Since the contest ends this Friday, I've decided to switch to
C++ (gasp!). But if any of you have advice on how to speed up this code,
it could help me advocate Haskell in the future.
It's supposed to match movie titles from an imported database to a
reference database. The version I've sent doesn't do anything very smart
- it's just doing literal title matches. The first argument to the
program is the filename of the table to be imported, and the second is
the filename of the reference table. The first line of each table is a
pipe-separated list of field names; the rest of the lines are records,
each a pipe-separated list of values.
The import files each have 3,000 records, and the reference table has
137,986 records.
Building the hash tables out of the files is quick - it just takes a few
seconds. But doing the matching of title_id in one table to title_id in
the other, in a nested loop between both tables, takes way too long.
It's matching two import titles (against each of the reference titles)
per second. It needs to do at least 20 per second to qualify for the
contest, and it's not doing anything fancy yet.
I tried various improvements to speed it up. One was to specifically
use ByteString, eliminating the AbsString class. Didn't make a
difference. Another was to use arrays instead of lists to store each
record, and precompute the indices of each of the fields within those
records. I also iterated over a list of keys instead of the list of
Maps, and only converted each record to a Map one at a time, hoping they
would be disposed of sooner. Instead of speeding up the program, this
slowed it down by a factor of 20!
I've profiled it, and I can't make much out of that. It seemed to be
spending 25% of its time doing scoring, and I though the problem must be
due to laziness, but I'm not sure.
So if anyone has any ideas how to speed this up by a factor of at least
10 times, it would be really appreciated! Even the Ruby solutions are
doing that, which is embarrassing.
Thanks,
Lyle
{-# OPTIONS_GHC -fglasgow-exts #-}
-- AbsString.hs
-- An abstract string class, which makes it easier to switch string representations.
module AbsString where
import Prelude as P
import Data.ByteString.Base (c2w, w2c)
import Data.ByteString.Char8 as BSC
import Data.ByteString.Lazy.Char8 as BSLC
import Text.Regex as RE
import Test.HUnit
class (Eq s, Ord s) = AbsString s where
s :: String - s
toString :: s - String
sLength :: s - Int
sAppend :: s - s - s
sConcat :: [s] - s
putStr :: s - IO ()
putStrLn :: s - IO ()
readFile :: String - IO s
lines :: s - [s]
split :: Char - s - [s]
(+++) :: AbsString s = s - s - s
(+++) = sAppend
instance AbsString String where
s = id
toString = id
sLength = P.length
sAppend = (++)
sConcat = P.concat
putStr = P.putStr
putStrLn = P.putStrLn
readFile fn = P.readFile fn
lines = P.lines
split c = RE.splitRegex (mkRegex (escapeRegexChar c))
regexMetaChars = \\|()[]^.*+?{}
escapeRegexChar :: Char - String
escapeRegexChar c = if c `P.elem` regexMetaChars then \\++[c] else [c]
instance AbsString BSC.ByteString where
s = BSC.pack
toString = BSC.unpack
sLength = fromIntegral . BSC.length
sAppend = BSC.append
sConcat = BSC.concat
putStr = BSC.putStr
putStrLn = BSC.putStrLn
readFile = BSC.readFile
lines = BSC.lines
split = BSC.split
instance AbsString BSLC.ByteString where
s = BSLC.pack
toString = BSLC.unpack
sLength = fromIntegral . BSLC.length
sAppend = BSLC.append
sConcat = BSLC.concat
putStr = BSLC.putStr
putStrLn = BSLC.putStrLn
readFile = BSLC.readFile
lines = BSLC.lines
split c s = BSLC.split c s
test_showString = TestCase $ do
let aStr = s Hello there :: String
assertEqual Hello there (toString aStr)
test_showByteString = TestCase $ do
let aStr = s Hello there :: BSC.ByteString
assertEqual Hello there (toString aStr)
test_showByteStringLazy = TestCase $ do
let aStr = s Hello there :: BSLC.ByteString
assertEqual Hello there (toString aStr)
runTests = runTestTT $
TestList [TestLabel test_showString test_showString,
TestLabel test_showByteString test_showByteString,
TestLabel test_showByteStringLazy test_showByteStringLazy]
{-# OPTIONS_GHC -fglasgow-exts #-}
-- TextTable.hs
-- Defines a TextTable type, which defines a map of strings to a record
-- of text fields.
module TextTable(TextTable(..),TextRecord,makeTable,lookupRecord,listKeys,listRecords) where
import Prelude hiding (putStr,putStrLn,readFile,lines)
import qualified Data.ByteString.Lazy as BSL (ByteString)
import Data.Array.Unboxed
import
[Haskell-cafe] Getting the latest
Hi folks, I am running GHC 6.4.1 on my Linux box at work, which is the latest packaged version for Ubuntu Dapper Drake. (They have a 6.4.2 package for Edgy, but I don't know how to install that. The Synaptic Package Manager seems to only want to install packages specifically labeled for Dapper Drake.) I tried downloading the latest binary snapshot. But when I try to unpack the archive, bzip2 tells me it's a bad archive. So, I downloaded the latest source version. That unpacked just fine, and I'm currently building it. My question is, when I do 'make install', will it just overwrite the version (6.4.1) I already have? Or will they go in separate places? I have no idea how it decides where to go. Right now ghc 6.4.1 is in /usr/local/bin/ghc. After I 'make install', will it be ghc 6.5? I don't want to screw up the installed package so it can't be updated later. Thanks, Lyle ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Optimizing a title matcher
Lemmih wrote: Do you have some test input online? I've attached some (very short) input files. Sorry I can't provide more - they're proprietary databases. I know that means you can't actually test the performance, but can only give me advice. At least you can run the program on them, and there is one match. - Lyle title_id|ref_title_id|importance|title|studio|run_time|rating|theatrical_release|home_video_release|box_office_gross|synopsis|actors|director 26246|157067|2|Sniper|TRI||R|29-JAN-93|04-AUG-93|18994653|A rebel leader and a wealthy drug lord are pursued in Panama by a marine sergeant and Oympic marksman.|Dale Dye;Aden Young;Tom Berenger;J.T. Walsh;Richard Lineback;Billy Zane|Luis Llosa 68308|174883|2|Northern Passage||97|||27-FEB-96|0|In the wilds of North America in the 1800s, Paul a young zoologist has pledged to keep as eye on his longtime friend's beautiful daughter, Nepeese. Nepeese and Paul fall in love, but their relationship is interrupted when an abusive fur trader kidnaps Nepeese. Starring Jeff Fahey.|Jeff Fahey;Neve Campbell| 68591|196655|2|Old Man And The Sea (1990)||97|||01-JUL-96||An old man heads out to sea, hooks a large fish, and battles a shark who has taken his catch.|Anthony Quinn;Alexis Cruz| 51506|190181|2|Shoot Out||95|||27-APR-99|||Gregory Peck;Robert F. Lyons| title_id|importance|title|studio|runtime|rating|theatrical_release|home_video_release|theatrical_box_office_gross|actors|director 214063|2|Elvis: His Best Friend Remembers|UNI||NR||30-JUL-02||Elvis Presley| 133868|2|Mighty Hercules, The - Speed Racer - V. 5||30|NR| 174883|2|Northern Passage|VMM|97|PG-13||18-JAN-00||Jeff Fahey;Neve Campbell;Jacques Weber;Lorne Brass;Genevieve Rochette|Arnaud Selignac 121430|2|Appointment With Death|WAR|||15-APR-88||960040|Peter Ustinov;Lauren Bacall;Carrie Fisher;Piper Laurie;John Gielgud;Hayley Mills;Jenny Seagrove;David Soul|Michael Winner ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Optimizing a title matcher
Robert Dockins wrote: Humm... well, double nested loops seems like the wrong approach. It may be. I had hoped it would be fast enough that way. Also, if you are using GHC, it's hashtable implementation has farily well-known performance problems. If all you care about is exact matching, then the operation is essentially a finite map intersection (if I've understood what you are trying to do). No, I don't just care about exact matching. I care about very fuzzy matching. It's just that the code I've implemented so far only does exact matching on the title strings. It's a first step. This is just a guess, but I suspect you will probably get much better performance (and better-looking code!) by just using Data.Map.intersection http://www.haskell.org/ghc/docs/latest/html/libraries/base/Data-Map.html#v%3Aintersection Thanks, but that won't help with the fuzzy matching. Alternately, there is the ternary trie implementation from Edison (http://www.eecs.tufts.edu/~rdocki01) that may also work for you. That may be useful. If you need to do prefix matching, then a trie is the way to go. You can probably code up a nice prefix-intersection operation using tries that should go pretty fast. If you have some other metric other than prefix in mind for partial matches, then things probably get a lot more complicated. You're probably looking at calculating minimum distances in some feature-space, which calls for pretty sophisticated algorithms if you need good performance. Yes, that's the kind of thing I'm looking at doing. Looking at edit distance. Thanks, Lyle ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Optimizing a title matcher
Bertram Felgenhauer wrote: Lyle Kopnicky wrote: [snip] listRecords :: AbsString s = TextTable s - IO [TextRecord s] listRecords (TextTable fields _ records) = do keyRecs - HT.toList records return $ map (fromList . zip fields . elems . snd) keyRecs Doing fromList again and again can't be good. Why don't you make tableFields a map that maps names to array indices? Then you can just pass the bare arrays along, and the later lookups will be cheaper, too. That might make a difference. It does spoil the interface a bit, since now the caller has to look up a field name to get an index, then use that to look up a value, instead of just using the field name to get the value. Now due to lazyness this will probably be evaluated in matchscore, because before that the resulting Map isn't used. Which is exactly where you said a lot (most?) of the time is spent. Yes, likely. I had to run on a small pair of files in order to get the profiling to work. So, probably more time was spent in matchScore than it admitted. (The overhead of the initial read would decrease as the table size increases.) Another thing is that you should compile your code with -O, but I guess you are already doing that. Yep. Thanks. - Lyle ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Optimizing a title matcher
Hi folks, It turns out Haskell is vindicated. It's my algorithm that was slow. As Robert Dockins pointed out, the double nested loop is just going to take a long time. As evidence, it turns out my C++ version is just as slow as the Haskell version. So, I'm going to go back to Haskell, but be more selective about which titles from the reference table I choose to match against, for any given import title. Thanks, Lyle ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Unable to profile program using Data.ByteString.Lazy
Donald Bruce Stewart wrote: Probably you didn't build fps with profiling as well? You can rebuild fps with: runhaskell Setup.hs configure -p as the first step. -- Don Thanks, I'll try it. Does that mean when I want to optimize my program, I'll need to rebuild fps without profiling? - Lyle ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Unable to profile program using Data.ByteString.Lazy
Hi folks, I wrote a program that uses some of the Data.ByteString libraries. I'm using GHC 6.4.1 and FPS 0.7. The program compiles and works just fine. But when I try to profile it, by compiling with -prof, I get: Failed to load interface for `Data.ByteString.Lazy': Could not find module `Data.ByteString.Lazy': locations searched: Data/ByteString/Lazy.hi Data/ByteString/Lazy.hi-boot /f/g/lib/fps-0.7/Data/ByteString/Lazy.p_hi Why can it find the module when it's compiling without -prof, but not when it's compiling with it? I would really like to get profiling to work. Thanks, Lyle ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] System threads?
Hi folks, I'm working on a project for which the solution is highly parallelizable. I've been writing it so far for GHC as a single-threaded app. I'd like to be able to split the job into multiple pieces, and spawn different system threads for each piece, so they will run on separate CPUs. Either each thread needs to write to the same IO handle, or else the results need to be collected when the threads are merged, so the results can all be printed. I'm working on Linux. What's the easiest way to accomplish this? Glasgow Parallel Haskell? Is there a Posix.Threads library? I understand that Haskell threads (Control.Concurrent) all run in one system thread, so would not take advantage of SMP. I suppose in the worst case I can write a shell program that divides up the problem, runs several worker processes to output intermediate results to files, then combines the results to the desired filehandle. Thanks, Lyle ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] SMTP, HTTP, Telnet
Hi all, Anybody know of some good Haskell libraries providing: an SMTP client, an HTTP client, or a Telnet client? There's a significant amount to these protocols, over and above the socket layer. Thanks, Lyle Kopnicky ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Bug in WinHugs?
Hi folks, I just installed the May 2006 release of Hugs. When I use the command-line version, the '$$' symbol to reference the last expression works fine. It does not work in WinHugs, but yields 'ERROR - Syntax error in expression (unexpected symbol $$)'. I typed ':set' to verify the '-r$$' option was set properly. Is this a known bug, or am I doing something wrong? Thanks, Lyle ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell] Mixing monadic and non-monadic functions
Bulat Ziganshin wrote:
Hello Ben,
Wednesday, September 14, 2005, 6:32:27 PM, you wrote:
BRG do { ... ; ... borrow E ... ; ... }
BRG is transformed into
BRG do { ... ; x - E ; ... x ... ; ... }
i strongly support this suggestion. actually, i suggest the same for
dealing with references (IORef/MVar/...), for example:
do x - newIORef 0
y - newIORef 0
z - newIORef 0
z := *x + *y -- translated to { x' - readIORef x; y' - readIORef y;
writeIORef z (x'+y') }
Right, I realize my suggestion is the same as Ben's. I just prefer a
more succinct notation, like special brackets instead of a keyword. I
like your idea about IORefs. I think it should work as well for
STRefs... perhaps it needs to belong to a type class, in a way?
- Lyle
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[Haskell] Re: Mixing monadic and non-monadic functions
It appears to me that:
* Many people don't like having to extract values from a monad on a
separate line, but would like to be able to mix monadic return values
into pure expressions, on the way to calculating a monadic result.
* Some people want to fix this by doing an implicit lifting operation on
functions, when their parameters are monadic
* It is not really clear what values are monadic and which aren't, so
the implicit lifting is a guessing game, and likely to produce
confounding errors.
* If you aren't going to be precise about what's in the monad and what's
not, you might as well use ML.
I propose instead an explicit, lightweight notation, with a simple
rewrite rule. Instead of:
do
putStr What is your name?
s - getLine
putStrLn (Hello ++ s)
I would like to write something like:
do
putStr What is your name?
putStrLn (Hello ++ {* getLine *})
In other words, we use some kind of special brackets (I don't care what)
to indicate that this value needs to be extracted from the monad on a
previous line, and inserted back here as a pure value. If these occur
multiply nested, they can be flattened out according to a dependency
rule. E.g.,
do
m1 {* m2 {* m3 *} v4 *} {* m5 *}
...would be rewritten as...
do
v3 - m3
v2 - m2 v3 v4
v5 - m5
m1 v2 v5
...and...
do
m1 {* {* m2 *} *}
...would become...
do
m2a - m2
v2 - m2a
m1 v2
I'm sure this has been suggested before... but what do folks think?
- Lyle
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[Haskell-cafe] Re: [Haskell] Haskell recruitment?
I think there are so few such opportunities that it would not overwhelm the list. I should also point out that you can post such openings at http://www.haskell.org/jobs.html by sending an e-mail to [EMAIL PROTECTED] and [EMAIL PROTECTED] Regards, Lyle Jochen L. Leidner wrote: Finally, would it be considered spam to post Haskell-realted job postings in this group? Thanks in advance. Regards, Jochen ___ Haskell-Cafe mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Partially-applied type synonyms?
Chung-chieh,
Well, I tried what you suggested, and it seems to work. Unfortunately,
it's not very useful. The point of creating MonadPCont, was, like
MonadCont or MonadState, to automatically provide features to a monad
built from a transformer, without having to redefine them. Since ContT
is the monad transformer, I want any monad created from it to
automatically support the MonadPCont operations. But they can't,
because I can't make ContT an instance of MonadPCont.
I can make FlipContT an instance of MonadPCont, but I can't make
FlipContT a monad transformer. So what you have to do is create your
layered monadwith ContT on top, and then apply the FlipCont constructor
to get a monad with the methods of MonadPCont. Now since FlipContT
isn't a monad transformer, you can't lift things into it. You can lift
them into ContT and then write a wrapper around that.
My point is that, unfortunately, I don't think it's very practical to
create this type class. I think the problem is that, although MonadCont
attempts to describe a monad as having certain operations, MonadPCont
attempts to describe a group of related monads as having certain
operations. They are related by being formed from the same type
constructor.
Here's the modified code:
module MonadPCont where
import Control.Monad
import Control.Monad.Cont
import Control.Monad.Trans
import Control.Monad.Reader
import Control.Monad.Writer
import Control.Monad.State
import Control.Monad.RWS
class (Monad (mc a), Monad (mc r)) = MonadPCont mc a r where
shift :: ((forall b. Monad (mc b) = a - mc b r) - mc r r) - mc r a
reset :: mc a a - mc r a
instance MonadPCont Cont a r where
shift f = Cont (\c - runCont (f (\x - Cont (\c' - c' (c x id)
reset m = Cont (\c - c (runCont m id))
data FlipContT m r a = FlipContT { unFlipContT :: (ContT r m a)}
instance Monad m = Monad (FlipContT m r) where
return x = FlipContT $ return x
(FlipContT m') = f = FlipContT $ m' = (unFlipContT . f)
runFlipContT :: FlipContT m r a - (a - m r) - m r
runFlipContT (FlipContT m) = runContT m
instance Monad m = MonadPCont (FlipContT m) a r where
shift f = FlipContT $ ContT $ \c -
runFlipContT (f (\x - FlipContT $ ContT $ \c' - c x
= c'))
return
reset m = FlipContT $ ContT $ \c - runFlipContT m return = c
- Lyle
Chung-chieh Shan wrote:
On 2004-08-31T09:55:10-0700, Lyle Kopnicky wrote:
Sorry, I don't think I made myself clear. I'm not defining PI, it's the
standard type binding operator, like lambda is the variable binding
operator. Maybe I could write it as 'II' so it looks more like a
capital pi. It's not a feature of Haskell, but part of type theory
(dependent types). I was mixing and matching and making it look like
Haskell. So instead of 'PI r - ContT r m', I could write 'flip ContT',
except that 'flip' needs to work on a type level instead of a value
level. Or I could write '(`ContT` m)', or 'ContT _ m', where the '_' is
a hole. Does this make sense now?
Yes, it makes sense now. You need to define
newtype FlipContT m r a = FlipContT (ContT r m a)
or more generally,
newtype Flip c (m :: * - *) r a = Flip (c r m a)
The rationale for disallowing matching partially-applied type synonyms
is that higher-order unification is undecidable.
See also:
Neubauer, Matthias, and Peter Thiemann. 2002. Type classes with
more higher-order polymorphism. In ICFP '02: Proceedings of the ACM
international conference on functional programming. New York: ACM Press.
http://www.informatik.uni-freiburg.de/~neubauer/papers/icfp02.pdf
http://www.informatik.uni-freiburg.de/~neubauer/papers/icfp02.ps.gz
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[Haskell-cafe] Partially-applied type synonyms?
Hi all, I'm trying to write a monad transformer class called MonadPCont, for partial continuations, which fits in with the Control.Monad libraries. I'm having a typing problem. What I have so far looks like this: module MonadPCont where import Control.Monad import Control.Monad.Cont import Control.Monad.Trans import Control.Monad.Reader import Control.Monad.Writer import Control.Monad.State import Control.Monad.RWS class (Monad (mc a), Monad (mc r)) = MonadPCont mc a r where shift :: ((forall b. Monad (mc b) = a - mc b r) - mc r r) - mc r a reset :: mc a a - mc r a instance MonadPCont Cont a r where shift f = Cont (\c - runCont (f (\x - Cont (\c' - c' (c x id) reset m = Cont (\c - c (runCont m id)) type ContT' m r a = ContT r m a instance Monad m = MonadPCont (ContT' m) a r where shift f = ContT (\c - runContT (f (\x - ContT (\c' - c x = c'))) return) reset m = ContT (\c - runContT m return = c) The error I get is: MonadPCont.hs:21: Type synonym `ContT'' should have 3 arguments, but has been given 1 In the instance declaration for `MonadPCont (ContT' m) i o' Failed, modules loaded: none. I guess it's not possible to partially apply a synonym for a type constructor. Essentially, I'm trying to do a 'flip', but at the type level. The underlying problem is that ContT is written to take the final result type (call it 'r') as the first parameter, and the underlying monad (call it 'm') as the second parameter, e.g. 'ContT r m a'. This is done so that 'ContT r' can be made an instance of the MonadTrans class. Unfortunately, I need 'PI r - ContT r m', along with a and r, to be a member of the MonadPCont class (PI is the type binding operator). So I thought I'd define ContT' to take the arguments the other way around. Unfortunately, it can't be partially applied. Any ideas, or is it just not feasible to work this class into the library? Thanks, Lyle Kopnicky ___ Haskell-Cafe mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Hiding functions
Simon, That makes good sense, as it's hard to read code that contains standard terms used in a nonstandard way. I was just concerned that the function name I wanted to use was already in the Prelude! Perhaps the Prelude 'catch', I reasoned, could be called 'catchIO', since it is specific to the IO monad, allowing people to write their own 'catch'. Or 'catch' could be a member of a type class, which could be overloaded for any new monad. But then I realized this argument could be made for practically every function in the Prelude. To dilute it with such abstraction would be a waste of resources. And there are loads of synonyms... I could use 'fling' and 'nab', 'punt' and 'snare', 'toss' and 'capture' Thanks for the point. - Lyle Simon Peyton-Jones wrote: It's an explicit Haskell 98 design choice http://haskell.org/onlinereport/modules.html 5.6.2 Shadowing Prelude Names The rules about the Prelude have been cast so that it is possible to use Prelude names for nonstandard purposes; however, every module that does so must have an import declaration that makes this nonstandard usage explicit. It's a decision one could debate, but it was an explicit choice. Simon | -Original Message- | From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Lyle | Kopnicky | Sent: 12 August 2004 20:23 | To: Haskell Cafe | Subject: [Haskell-cafe] Hiding functions | | Hi all, | | I'm working on a program that uses my own brand of exceptions, and I | created two functions called 'throw' and 'catch'. In order for this to | work, I hide the Prelude 'catch' in my module, called 'Cont.hs'. Thus: | | module Cont where | import Prelude hiding (catch) | ... | throw = ... | catch = ... | | This works hunky-dory until I create another file that imports Cont. I | get a conflict when I use 'catch', so I have to hide the Prelude one again: | | import Prelude hiding (catch) | import Cont | ... | ... throw ... | ... catch ... | | So I'm a bit annoyed by this 'propagation' of hiding clauses. Then I | created a new file, that redefined throw: | | module ResumableExceptions where | import Cont hiding (throw) | import qualified Cont (throw) | ... | throw = ... Cont.throw ... | | Finally, I created a file using ResumableExceptions: | | import Cont hiding (throw) | import ResumableExceptions | ... | ... throw ... | | If I wanted to also use 'catch' I'd have to hide that from the Prelude | as well. | | I can't use type classes to solve this problem, because the types of the | two 'throw' functions are different. | | Perhaps I should just make up new names for these things, eh? But there | might be code that uses 'throw' and doesn't really care which one is | used, and it would be nice to just modify the import line and be done | with it. | | Any opinions? | | Thanks, | Lyle | ___ | Haskell-Cafe mailing list | [EMAIL PROTECTED] | http://www.haskell.org/mailman/listinfo/haskell-cafe ___ Haskell-Cafe mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Hiding functions
Alistair, I'm throwing my own exceptions in my own monad, not the IO one. But thanks for pointing me to the stuff about dynamic types. I'm going to be creative and pick some new names. - Lyle Bayley, Alistair wrote: What is wrong with creating your own catch and throw with different names? e.g. data MyException = MyException ... deriving (Typeable, Show) catchMyEx :: IO a - (MyException - IO a) - IO a catchMyEx = catchDyn throwMyEx :: MyException - a throwMyEx = throwDyn But there might be code that uses 'throw' and doesn't really care which one is used, and it would be nice to just modify the import line and be done with it. Can you expand on this? (more example code?) If you want to throw your own exceptions, then you must use throwDyn/catchDyn, so you have to use something other than catch/throw anyway. Alistair. ___ Haskell-Cafe mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Combination-lock problem
Even shorter: c=mapM(\k-[0..k]) - Lyle Fritz Ruehr wrote: Well, as far as that goes, we can shave off a little bit (around 7%) this way: combs = mapM (\k-[0..k]) (As a bonus, it's even a bit more cryptic/symbolic, in the fine tradition of APL one-liner character-shavings.) But who's counting? :) :) :) -- Fritz Ruehr ___ Haskell-Cafe mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Closed Classes
Notwithstanding module Y, I don't think you should infer in module X that g::Int (or, rather, Int-Int). Since f is defined in a type class, it should be polymorphic, and so should g. When you apply g to a type, it will check to see what instances are available, and match only if Int is the type of the variable. But there's no reason to restrict the type of g itself. - Lyle [EMAIL PROTECTED] wrote: Informally, what I see as the defining rule for closed world is: an expression is typed according to the set of definitions that are visible in the context in which it is used. Other possibilities exist, but the nice thing about this is that it is an extension of what happens without overloading. With this definition, given _____ | module X (f,g) where | | module Y where | | | || | class A a where | | import X | | f :: a - a | || | instance A Int where | | instance A Float where | | f = id | | f x = x + 1.0| | | || | g x = f x | | h x = g x | - -- we would infer: g::Int (since the context in g's definition has only f:Int) and thus h::Int in Y (since the context in h's definition has only one g::Int). If h was defined as h x = f x in Y, *then* it would have a polymorphic type (because there are two instances of f in Y). Carlos ___ Haskell-Cafe mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell-cafe ___ Haskell-Cafe mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Combination-lock problem
Henning Thielemann wrote: On Wed, 11 Aug 2004, Lyle Kopnicky wrote: Here's my version: combs [] = [] combs [n] = [[i] | i - [0..n]] combs (n:r) = let combsr = combs r in [i:cr | i - [0..n], cr - combsr] Since there is one zero combination, it should be combs [] = [[]] Ah, yes. I knew I must be missing something. That would be a lock which has no numbers on it, but can be opened at any time. Then you can also remove the definition of combs [n] . What is the advantage of introducing 'combsr' instead of using 'combs r' immediately? I initially did that to save recalculation, but later shifted things around, and now I see there is no need for it. Thanks. Here is the improved version: combs [] = [[]] combs (n:r) = [i:cr | i - [0..n], cr - combs r] - Lyle ___ Haskell-Cafe mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Library sizes (was: Toy application advice wanted)
I don't want to pick on any particular library, as this issue can pop up with any library in any language. I feel it's an issue which has been addressed before, but the solutions are largely ignored. This is most likely because 1) people assume we have plenty of space or 2) the library isn't yet complete, and it's easier to statically link a big library for now, and worry about alternatives later. If I were writing a library, I probably wouldn't be too concerned with the issue myself. It seems there are two ways to address this problem: 1) Shared libraries. Why not link the library dynamically instead of statically? Is this possible with GHC? Then multiple applications using the library wouldn't balloon the memory use, but share a copy of the same library. For simple development and testing, it's easier to statically link, since we only have to worry about one file. But if we expect people to run many programs using this library, we ought to be more careful about space usage. Dynamic linking ought to be an option. 2) Linking in only what's used. If a simple 'Hello, World!' program only needs a window and some buttons, why link in all the code for other widgets? Is there a library format which allows pulling out only those operations which are needed? An alternative is to recompile the library code with the program each time, throwing away dead code - that is, the library code which is never called. Recompiling the library code with the application takes longer, but need only be done once the program is ready for distribution. If anyone knows of existing solutions in either of these areas, please inform us. - Lyle Kopnicky Duncan Coutts wrote: On Wed, 2004-05-05 at 16:24, Andrei de A. Formiga wrote: I'm finding wxHaskell very nice, and a wxWidgets binding is something many other "advanced" languages don't have (even OCaml). The only downside is having a 'Hello World' GUI application with 7 Mb... but it runs quite well and smooth once it's loaded. We have the same problem with gtk2hs. A stripped simple(ish) prog weighs in at about 2.5Mb. I'm not quite sure what's in there that makes it so big. Duncan ___ Haskell-Cafe mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell-cafe ___ Haskell-Cafe mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Toy application advice wanted
David Roundy wrote: I think that sounds like a good idea (not doing a GUI just yet) but would recommend that perhaps you could do something pretty impure in terms of file or directory browsing. That wouldn't involve going beyond the standard libraries, but might give you some idea of the expressive power of the languages in terms of IO actions. I'm thinking something like a recursive grep, or wc -l... except preferably a bit more tailored to the sort of IO you'll have to do in your actual application. I guess the trick would be in finding something tough enough, since wc -l would be something like a two-liner... A one-liner: main = interact (show . length . lines) - Lyle Kopnicky ___ Haskell-Cafe mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: How do I sleep in Ghc?
Here's a POSIX implementation of a sleep function in C, as found in the book "Advanced Programming in the UNIX Environment": http://www.yendor.com/programming/unix/apue/lib.svr4/sleep.c AFAIK, all the GHC platforms, including Windows, are POSIX compliant. You could compile this code separately and call it via the FFI. If it doesn't work on Windows, you could instead call: Win32::Sleep(TIME) [CORE] Pauses for TIME milliseconds. The timeslices are made available to other processes and threads. Hope that helps, Lyle Kopnicky BTW, you have a very interesting disclaimer in your message. I hope I will not go to jail for reading it. [EMAIL PROTECTED] wrote: Hi there, In Ghc, how do I sleep for say, 1 minute? I'm trying to write a simple file arrival listener and could not find the sleep api. Can haskell do it at all? Thanks. Ben. This message is intended only for the addressee and may contain information that is confidential or privileged. Unauthorized use is strictly prohibited and may be unlawful. If you are not the intended recipient, or the person responsible for delivering to the intended recipient, you should not read, copy, disclose or otherwise use this message, except for the purpose of delivery to the addressee. If you have received this email in error, please delete and advise us immediately. ___ Haskell mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell ___ Haskell mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell
