Re: [Haskell-cafe] Markdown extension for Haddock as a GSoC project
How's about Creole? http://wikicreole.org/ Found it via this: http://www.wilfred.me.uk/blog/2012/07/30/why-markdown-is-not-my-favourite-language/ If you go with Markdown, I vote for one of the Pandoc implementations, probably Pandoc (strict): http://johnmacfarlane.net/babelmark2/ (at least then we're not creating yet another standard...) Alistair On 24 April 2013 07:23, Mateusz Kowalczyk wrote: > -BEGIN PGP SIGNED MESSAGE- > Hash: SHA1 > > Greetings, > > In light of fairly recent discussion, on this mailing list, I decided > to investigate the topic of Markdown support for Haddock. The archives > of the recent discussion can be seen at [1]. This post aims to > summarise the current state of discussion. I do aim to file a proposal > for a GSoC project on this issue but it'd be foolish to file a > proposal for a project aiming to benefit the community without > consulting the community itself. > > Here are some main points and ideas gathered: > * reSt seems to have a small following - quite a bit smaller than the > Markdown community. In fact, there seems to be a significant amount of > people pushing for Markdown which contrasts what we can read in a > topic from 2008 at [2]. I guess it just shows how much Markdown has > gained in popularity in recent years. > * There are issues with using Markdown even before we attempt to use > it for Haskell documentation: > * There exists no formal specification or semantics. It would seem > that a significant number of Markdown parsers are creating by reverse > engineering an already existing parser. This is bad because we end up > propagating the bugs and workarounds around ambiguity that the > original parser has. > * As a follow-up to the previous point, the (vanilla) Markdown is > ambiguous and there is nothing to resolve it. As Richard A. O'Keefe > pointed out, there exist situations where it's not possible to infer > the semantics of Markdown from its official implementation and the > result is parser/writer-specific [6]. > * John MacFarlane has already written a Markdown parser in Haskell. It > can be read at [3]. This means that the new extension would not need > to rely on Pandoc. He says ``I have an experimental thing here that > could be used as a basis (it's 7x faster than pandoc and uses 1/5 the > memory, BSD licensed)''. This is great! The post can be seen in full > at [4]. > * An alternative idea was to simply write a writer module for Pandoc > for Haddock. > * A reader module is already present. > * According to John MacFarlane, Haddock is not expressive enough to > take advantage of this. Furthermore, Pandoc doesn't have some > constructions that Haddock does [4]. > * Comes back to the problem on relying on such a large package as > Pandoc. > * Yet another proposal was rather than introducing Markdown to > concentrate on fixing current issues and adding features to Haddock as > it stands [8]. This is one of the options listed at the short blog > post at [14] by Johan Tibell. > * David Waern, one of Haddock maintainers admits that Haddock lacks > active development and it has been that way for a longer time. Having > said that, he seems to believe that Markdown integration is a project > that can realistically be completed over summer. Such project would be > able to use the existing HTML backend in Haddock. [9]. > * Math expressions were requested and MathJAX was suggested as a > solution at [5]. math.stackexchange.com uses MathJAX and it works > quite well. Personally, I believe that Haskell documentation would > benefit from this simply due to the academic nature of the language. > * Support for Literate Haskell would be a welcome addition as > suggested by Andrew Butterfield at [7]. > * There are issues with CPP and LHS in regards to using Markdown in > documentation. They are pointed out at [10] by John MacFarlane and > others that he's replying to. > * As pointed out 5 years ago at [11], we'd have to do some > preprocessing on current, fairly critical sections of comments used by > Haddock. I believe these are fairly useful and it would be a shame to > see them go. > > > I hope I haven't missed anything of high importance in a list above. > When researching the topic, issues with Markdown quickly become > apparent. Today, there are tens of different Markdown flavours: each > company has different needs and each company interprets the vague > original documentation in a way that's convenient to them. In these > situations, topics, e-mails and blog posts like this one happen. There > is a call to action from October 2012 at [12] but there seems to be > absolutely no progress on any of the miraculous things mentioned in > the post. As a result of that post, a W3C community was formed at > [13]. It's clear that the community is inactive and no progress > towards a solution was made. > > Having considered all information gathered here, I believe this would > make a good GSoC project. There has been interest in this for Hask
Re: [Haskell-cafe] Split and substitution using regex-pcre
You cannot bend the split package to your needs? http://hackage.haskell.org/packages/archive/split/0.2.1.2/doc/html/Data-List-Split.html Some combination of splitWhen and a pcre-based predicate? On 24 February 2013 22:44, Simon Marechal wrote: > I could not find the perl-equivalents of these functions on Hackage, so > I quickly wrote mine. Code is there: > > https://github.com/bartavelle/pcre-utils > > It should behave like perl (not really tested actually), and do strange > things like : > > > splitCompile "a" "b" > Right ["","","","","b"] > > splitCompile "a" "baaa" > Right ["","","","","b"] > > This will go on Hackage as I need it for the language-puppet package, > but I am interested in comments, especially concerning the namespaces: > * is the name of this package OK ? > * is the name of the package OK ? > * should I work with the regex-pcre maintainer to try to merge it ? > > > ___ > 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] ANNOUNCE: Sylvia, a lambda calculus visualizer
On 2 October 2012 15:23, Conrad Parker wrote: > > I'd love to see a game which incrementally teaches reduction and > expansion steps in the way that DragonBox [http://dragonboxapp.com/] > teaches algebra. That would be a learning mode like Angry Birds, where > new combinator birds are introduced every few levels and a small > selection of useful birds are provided to help solve each level. > > (Lambda calculus really should be a kids' game, grown-ups always make > it seem more complex than it is). Not sure if it's what you're after, but I was reminded of this (models untyped lambda calculus): http://worrydream.com/AlligatorEggs/ Alistair ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Does anyone maintain trac.haskell.org?
On 9 December 2011 10:39, Justin Bailey wrote: > The community Trac hosting server isn't sending email, which Trac requires. > > I've submitted several tickets to supp...@community.haskell.org but > gotten no response. > > Does anyone maintain that server anymore? Had the same problem in July. Raised a ticket etc. I don't think there is anyone actually responsible for the trac server. Alistair ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] blog software in Haskell?
On 31 October 2011 22:14, Ketil Malde wrote: > > I just upgraded my server, and set up everything again. Except > wordpress, as 1) I'm not too fond of its user interface, and 2) it's a > big pile of PHP, difficult to keep updated, and basically a disaster > waiting to happen (and in fact, it was hacked at one point). > > Before I enable it again, is there any alternatives I should consider? > Preferably written in Haskell, of course, but other suggestions welcome > as well. http://gitit.net/ ...has git and darcs storage. http://www.haskell.org/haskellwiki/Web/Content_Management There is also orchid: http://hackage.haskell.org/cgi-bin/hackage-scripts/package/orchid-0.0.6 https://github.com/sebastiaanvisser/orchid https://github.com/sebastiaanvisser/orchid-doc which I recall was quite pretty, but I cannot find an online demo. Alistair ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Real CMS Application in Haskell
On 4 September 2011 17:46, Haisheng Wu wrote: > Hello guys, > I googled for a real open source CMS application in Haskell but have no > luck. > So I'm wondering if Haskell is used very little in Web development area. > Thanks. > -Simon There was this, quite some time ago: http://article.gmane.org/gmane.comp.lang.haskell.cafe/21159 However, looking at the site now I thing it's been replaced by something more popular. Perhaps there's an interesting story behind that... Alistair ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Network.CGI and SQL Queries
> There's an odd error every time I try to run this code: > > > sqlReaderIO = do > handle <- connectSqlite3 "table2.db" > scoresSql <- quickQuery' handle "SELECT * FROM pachinkoScores ORDER BY > score, name" [] > let scores = map (map (\x -> fromSql x :: String)) scoresSql > return (show scores) > > ... > > cgiTMain = do ... > scoresPassed <- sqlReaderIO > output . renderHtml $ (inputForm n ss) maybe (inputForm n ss) > (\mT -> page "Loading..." (visual t v a mT ss) n v a (t + 1) mT) maxT > > > When I remove the "scoresPassed <- sqlReaderIO" line, the code run smoothly. > Nothing else references "scoresPassed". The ghc, however, gives me this > error when the line is included: > > tankwSql.hs:144:15: > No instance for (MonadCGI IO) > arising from a use of `output' > Possible fix: add an instance declaration for (MonadCGI IO) > In the first argument of `(.)', namely `output' > In the expression: output . renderHtml > In the expression: output . renderHtml $ inputForm n > > tankwSql.hs:147:30: > Couldn't match expected type `CGIT m0 CGIResult' > with actual type `IO CGIResult' > In the first argument of `handleErrors', namely `cgiTMain' > In the second argument of `($)', namely `handleErrors cgiTMain' > In the expression: runCGI $ handleErrors cgiTMain You probably need to lift the sqlReaderIO action from IO into CGIT. liftIO should do it. You should consider adding type sigs to cgiTMain and sqlReaderIO, so it's clear which monad you're in for each function. Alistair ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] External system connections
12 July 2011 05:49, Michael Snoyman wrote: > > As for Bryan's resource-pool: currently I would strongly recommend > *against* using it for any purpose. It is based on > MonadCatchIO-transformers[2], which is a subtly broken package. In > particular, when I tried using it for pool/persistent in the first > place, I ended up with double-free bugs from SQLite. Do you have a reference explaining this brokenness? e.g. a mailing list message? I wasn't aware of this. Are the other MonadCatchIO-* packages also broken? Alistair ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Oracle Sessions in Takusen
On 3 June 2011 05:35, Kevin Quick wrote: > Dmitry, > > I'm not directly familiar with Takusen or its use with OracleDB, but I would > hazard a guess that the withSession is doing FFI resource management and > that resources obtained inside the withSession environment are no longer > valid outside of the withSession. > > If this is the case then I would expect the following to work: > > replicateM 2 (do > withSession (connect "x" "x" "x") (do > res <- doQuery ... > liftIO $ print res > ) > ) > > If this really is the case then it seems that withSession shouldn't be > exporting FFI-based resources. > > -KQ You're right, withSession shouldn't be exporting FFI obtained resources, and I don't think it does. There are some known issues with the Oracle code, where it allows buffers to fall out of reference (and thus be gc'd) before the C libs have finished with them, thereby causing segfaults. The known problems are around bind variable buffers, so this looks like a new issue. At least we're collecting a nice corpus of programs that cause the Oracle backend to fail :-) I'd love to have more time to work on it... If you don't need the Oracle-specific functionality, for now I suggest using the ODBC driver as a substitute, as this seems to be (more) reliable. Alistair ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Encoding-aware System.Directory functions
On 30 March 2011 20:53, Max Bolingbroke wrote: > On 30 March 2011 07:52, Michael Snoyman wrote: > > I could > > manually do something like (utf8Decode . S8.pack), but that presumes > > that the character encoding on the system in question is UTF8. So two > > questions: > > Funnily enough I have been thinking about this quite hard recently, > and the situation is kind of a mess and short of implementing PEP383 > (http://www.python.org/dev/peps/pep-0383/) in GHC I can't see how to > make it easier on the programmer. As Jason points out the best you can > really do is probably: > > 1. Treat Strings that represent filenames as raw byte sequences, even > though they claim to be strings > > 2. When presenting such Strings to the user, re-decode them by using > the current locale encoding (which will typically be UTF-8). You > probably want to have some means of avoiding decoding errors here too > -- ignoring or replacing undecodable bytes -- but presently this is > not so straightforward. If you happen to be on a system with GNU Iconv > you can use it's "C//TRANSLIT//IGNORE" encoding to achieve this, > however. > http://www.haskell.org/pipermail/libraries/2009-August/012493.html I took from this discussion that FilePath really should be a pair of the actual filename ByteString, and the printable String (decoded from the ByteString, with encoding specified by the user's locale). The conversion from ByteString to String (and vice versa) is not guaranteed to be lossless, so you need to remember both. Alistair ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] [Haskell] Problems with (projects|community).haskell.org
On 10 February 2011 22:03, Dominique Devriese wrote: > Also, is there any news yet on a procedure for community members with > accounts on projects.haskell.org to get access to them again? My ssh > publickey login is no longer being accepted. I had an account mainly > for hosting the darcs repo and the website for my project > grammar-combinators. The website has been down for a couple of weeks > now. > > Dominique > > P.S.: This is not a complaint, I'm just hoping for a status update. > P.P.S.: Thanks to the people working on fixing this.. Any update on this? Alistair ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ANNOUNCE: Takusen 0.8.6
At the risk of seeming a bit defensive, I'll respond to some of these points... > Despite this, it seems to have a couple faults: > * Few tutorials, aside from the Haddocks in Database.Enumerator True. I put a bit of effort in to writing the docs in Database.Enumerator as a sort of tutorial, but it doesn't work as well as a properly written tutorial. Perhaps this would be better placed on the wiki, but it's quite a bit of work, assuming you would prefer something more than a simple cut-n-paste from the generated docs. > * Very crufty old code in some spots (I see lots of references to > GHC 6.6 and the 'extensible exceptions' changes in the cabal file > among other places, which I believe we're all well beyond now. There > also seems to be random tidbits that could be removed in favor of a > library/removed because they're not necessary.) This should IMO all be > removed under the argument "Get a more recent GHC" although people may > disagree here. Maybe... We've put some effort into supporting older versions of ghc, mainly because quite a few distributions have quite long update cycles. If you're stuck in an environment (some unis, some employers?) where you are only allowed tools from the last stable distribution, you may well be many releases behind current ghc. If everyone agrees that 6.8 should be the oldest ghc we should test and support, then that does make things a little simpler. Are there any distros still shipping with ghc-6.6? BTW, I thought extensible-exceptions first shipped with 6.10. I don't think everyone is off 6.8 yet, so we'd want to keep that cabal switch in for a little longer if we intend to support 6.8. > * It would be nice if we could make it depend on nicer libraries > instead of rolling its own stuff - for example, we have Lato's > excellent iteratee package, and Bas van Dijk has written a (IMO > woefully underappreciated!) 'regions' package with encapsulate the > lightweight monadic regions idea Oleg proposed. Of course, due to > design, neither of these may work properly for Takusen's case, and if > they did they would very likely facilitate API changes, but it's > something I've been thinking about in the name of making the library > smaller and more lightweight. iteratee and regions were both released well after Takusen was written. I think iteratee is just the same idea generalised to other types (Binary, ByteStrings, IO, etc). Perhaps it would help to use it and standardise the interface, but I haven't looked into it at all. It looks like it might be a considerable amount of work. Using regions might be more feasible (i.e. easier), but again I haven't considered it. Takusen's implementation also pre-dates regions considerably, and it works well for us as is. The actual implementation is very little code. That is, in both cases I don't see a big benefit from switching over to these libraries, considering the amount of work I think it would take (esp for iteratee). There are plenty of other things on the to-do list which I think should take higher priority e.g. - splitting Takusen into multiple packages: a core interface, and then separate packages for each backend. - better docs, as you've requested. - support for blobs/clobs As Gregory just pointed out, using other libs adds further dependencies to Takusen. One of our earlier goals was to make it easy to install, which in the days before cabal meant fewer dependencies on external libs. cabal now mitigates that concern considerably, so perhaps we should relax more now when it comes to using external libs. Here is the list of things that I can think of right now which are currently internalised in Takusen, but which are also implementated in hackage libs: - extensible exceptions - EMonadIO - regions - iteratee I'm not saying the way it is now is right or best, but it got there through various historical decisions, which were made with the best information available at the time, and in environments that differ from the current. Alistair ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Anyone here from New Zealand?
On 24 July 2010 09:58, Hamish Mackenzie wrote: > On 24 Jul 2010, at 02:15, Tim Matthews wrote: > > Any of the haskellers here from NZ? > > I am in Wellington, Stephen is near Palmerston North. There are a few others > elsewhere I think. I'm currently moving from the UK back to Wellington (well, Paraparaumu, but looking for work in Wgtn), so maybe will try to get in touch when we're there. Won't actually be there until September. There is this page, which has not been promoted in a while, I think: http://www.haskell.org/haskellwiki/Haskell_user_locations (Frappr seems to be dead, now.) Alistair ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] gtk2hs and ghc-6.10.4 on Windows (Vista)
On 16 February 2010 17:57, Neil Mitchell wrote: > Hi Serguey, > > A GHC 6.10.4 version of Gtk2hs: > > http://www.mail-archive.com/gtk2hs-de...@lists.sourceforge.net/msg00340.html > > I used to recommend Gtk2hs over wxHaskell for GUI development as there > was always a version that worked on Windows with the latest GHC > release. I think I might have to switch back to recommending C# for > GUI development... Is there a trick to getting this installed? I have run the installer in a Vista machine, both as user and admin, and the installation is mostly successful, except that the packages are not registered with ghc-6.10.4. Also, the first step of the install complains that "GHC does not appear to be installed correctly, try reinstalling GHC version 6.10.4. Setup found what appears to be a non-working installation of GHC in ..." What test does it apply to determine if GHC is working or not? It can run the gtk-demo, so it's not all bad, but I can't build anything that uses it (like Yi). Alistair ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Haskell IDEs on Windows; gtk2hs
I thought I'd try some of the Haskell IDEs: eclipsefp, leksah, and yi. So far, leksah requires gtk2hs (and apparently yi can use it too?), and the latest gtk2hs installer for Windows doesn't like the latest Haskell Platform, so I'm going to try building gtk2hs from source, unless anyone tells me that it's a waste of time. Building yi fails with: Yi\Prelude.hs:182:9: Duplicate instance declarations: instance Category Accessor.T -- Defined at Yi\Prelude.hs:182:9-38 instance Category Accessor.T -- Defined in data-accessor-0.2.1.2:Data.Accessor.Private cabal: Error: some packages failed to install: yi-0.6.1 failed during the building phase. The exception was: exit: ExitFailure 1 Presumably data-accessor has been updated, but yi has not? What is the easiest fix? Downgrade to an earlier version of data-accessor? So that just leaves eclipsefp. Still trying to figure out how to install eclipse plugins... Alistair ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] programmatic DB interface?
> What is currently the recommended > higher level data base interface for Haskell? > > I want to construct queries in a programmatic/algebraic way, > > Would takusen help? Where's its home page? > this does not work: http://darcs.haskell.org/takusen/ Takusen still requires you to supply queries as strings, so no, it wouldn't help. BTW, it has moved to http://code.haskell.org/takusen The only game in town is HaskellDB, AFAIK. Alistair ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Haskell Platform
> How are the efforts on Haskell Platform for GHC 6.12.1 going? > > I'm considering joining those brave heroes. Where can I apply? Joining the mailing list would be a good place to start: http://projects.haskell.org/cgi-bin/mailman/listinfo/haskell-platform Alistair ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Takusen - reading from one db inserting into another
Hello Günther, > I know how to use Takusen with a *single* connection, but I cannot figure > out how to read from one database while inserting to another. At present it's not possible. The lats time you asked about it, Oleg and I tried a design where the DBM monad becomes a DBMT monad transformer. This permits multiple connections, but the resulting user-land code didn't work as well as I wanted. If you like I can try to tidy it up and send you the darcs patch. Alistair ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: ssh ports for monk and nun?
> Trying to get ssh working via putty from behind my company firewall. > Had some success in the past with sourceforge because they had ssh > daemons listening on ports 80 and 443, to aid prisoners like myself. > Does anyone know if the monk (darcs.haskell.org) and nun > (code.haskell.org) servers accept ssh on ports other than 22? I should also have said: I'm open to suggestions and advice on using darcs+cabal+ssh with restrictive firewalls and http proxies. I currently have cntlm (an authenticating proxy server) installed, so I can use cabal (and darcs get will work with this too), but I want to be able to push patches too. Alistair ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ssh ports for monk and nun?
2010/1/12 Jason Dusek : > Monk and nun? The haskell.org code/project/... servers: http://www.haskell.org/haskellwiki/Haskell.org_domain ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] ssh ports for monk and nun?
Trying to get ssh working via putty from behind my company firewall. Had some success in the past with sourceforge because they had ssh daemons listening on ports 80 and 443, to aid prisoners like myself. Does anyone know if the monk (darcs.haskell.org) and nun (code.haskell.org) servers accept ssh on ports other than 22? Thanks, Alistair ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Relational Algebra
> has anybody already developed an EDSL for relational algebra? > > HaskellDB does that, but its current implementation only allows for > generating SQL, are there other implementations? Hello Günther, Ganesh did something called squiggle a while ago: http://code.haskell.org/squiggle/unstable/ I've done something similar but it's not published or hosted anywhere, so no link. Can upload it to code.haskell.org if you're interested. Both of our projects just generate SQL though, AFAIK. Was there something else you wanted to generate? Alistair ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Takusen: *** Exception: readUTF8Char: illegal UTF-8 character 252
Hello Günther, It looks like Access is not using UTF8 as its text encoding. I have Access at work, so I can look into this at some point. The ODBC code assumes the encoding is always UTF8. For some drivers (e.g. PostgreSQL) you must configure the ODBC driver correctly to provide UTF8. Does Takusen work with Access for US7ASCII text? If not, this would suggest that Access is using UTF16 (which is common on Windows). Alistair 2009/9/8 Günther Schmidt : > Hi all, > > I'm trying to use Takusen ODBC on Windows. > > I'm using a German WinXP Pro and try to connect to an MS Access database. As > soon as I try to do some inserts the above mentioned exception shows up. > > Does anyone know a work around for this? > > Günther > > ___ > 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] Takusen - is anyone currently using it on Win32 - ODBC?
2009/8/23 Günther Schmidt : > > is anyone currently using takusen with odbc on Win32? In particular with MS > Access? > > I'm asking because I noticed that when database libraries are declared to > work with ODBC no one seems to mean Win32 ODBC, but rather Unix ODBC. Yes. The ODBC backend is tested on Win32, although not with MS Access (Oracle, PostgreSQL, and MS SQL Server have been tested). If you have problems with MS Access, do let me know. Alistair ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] ANN: Takusen 0.8.4
ANN: Takusen 0.8.4 This is mainly a "get it working with ghc-6.10" release. Changes since 0.8.3: - ODBC support: some bug fixes, and basic support for Out-parameters. There is at least one major outstanding bug with Out-parameters, where marshalling a String output bind-variable doesn't work correctly (if it was modified, you still get the String you passed in back, rather than the new String). - Sqlite: bug fix for resource leak: if a command (like rollback or commit) raised an error, the prepared-statement handle was not closed. - cabal: requires cabal 1.6 (or later). With ghc-6.6 on Windows you will need a later cabal than 1.6.0.1, as there is a bug which prevents building (setup configure fails with "setup: fdGetMode: invalid argument (Invalid argument)"). Eric Mertens patch for ODBC on OS x. Greg Leclerq patch for cabal 1.6. Thanks also to Austin Siepp and Brian Callendar for their patches. - ghc-6.10: will build with ghc's 6.10, 6.8, 6.6. Note that Takusen won't work with ghc-6.10.2 out-of-the-box, because the time package is missing. If you install time manually then it should be OK (but this is untested). We use the new extensible exceptions, but we have done so by including it within our own source tree. This will make it easier to use Takusen with older ghc's, and reduces the number of external package dependencies. We have dropped support for 6.4. That's not to say Takusen isn't usable with 6.4, just that we no longer test that configuration. The release bundle: http://hackage.haskell.org/packages/archive/Takusen/0.8.4/Takusen-0.8.4.tar.gz The latest code: darcs get http://darcs.haskell.org/takusen Docs: http://darcs.haskell.org/takusen/doc/html/index.html If you have cabal-install, then this command should work: cabal install Takusen --flags="sqlite odbc oracle postgres" ... but it doesn't (at least for the version of cabal-install that I have) because the .tar.gz file I uploaded has a bogus checksum. A comprehensive description of API usage can be found in the documentation for module Database.Enumerator (look for the Usage section): http://darcs.haskell.org/takusen/doc/html/Database-Enumerator.html Note that the haddock docs won't build with cabal-1.6.0.2 or earlier. This is because our literate-haskell source files need to be properly preprocessed before being passed to haddock. At the time of writing, you'll need the cabal HEAD to build the docs. Future plans: - Output bind-parameters and multiple-result sets for ODBC - support for Blobs and Clobs - FreeTDS backend (Sybase and MS Sql Server)... maybe For those of you unfamiliar with Takusen, here is our HCAR blurb: Takusen is a DBMS access library. Like HSQL and HDBC, we support arbitrary SQL statements (currently strings, extensible to anything that can be converted to a string). Takusen's 'unique-selling-point' is safety and efficiency. We statically ensure all acquired database resources - such as cursors, connection and statement handles - are released, exactly once, at predictable times. Takusen can avoid loading the whole result set in memory, and so can handle queries returning millions of rows in constant space. Takusen also supports automatic marshalling and unmarshalling of results and query parameters. These benefits come from the design of query result processing around a left-fold enumerator. Currently we fully support ODBC, Oracle, Sqlite, and PostgreSQL. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Takusen, postgres and boolean fields
2009/4/25 Sasha Shipka : > When I did SELECT statement I handled boolean field as String, and > convert it to Bool. > However when I did update or insert, I must bind those values, then > takusen calls foreign postgres library and function with "?" and > values of proper type. So I cannot use neither Bool neither String in > bindP. > > Instead of binding, I've used ugly hack : > "update some_table set some_boolean_field = ? ..." [bindP True, ...] > is replaced with > (printf "update some_table set some_boolean_field = '%s' ... " "t") [...] > I really hate it and I hope there is better way to do it. It should be pretty simple to add Bool instances to the class that handles bind variable marshalling. I'll look into it on Monday. As a workaround for now, can you use the CAST sql function to convert text to bool values in Postgres? Alistair ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] strange performance issue with takusen 0.8.3
2009/4/6 Marko Schütz : > > I have an application where some simple data extracted from some > source files is inserted into a PostgreSQL database. The application > uses Takusen and is compiled with GHC 6.8.3. Some (59 in the test > data) of the selects take on average 460ms each for a total time for > this sample run of 30s. I prepare one select statement at the > beginning of the run into which I then bind the specific values for > every one of the selects. It does not seem to make a difference > whether I do this or whether I just use a new statement for every > select. > > For comparison, I have collected the SQL statements in a file with > PREPARE ... and DEALLOCATE for _every_ select and then run this file > through psql. This takes 2s! Hello Marko, I'm finding it hard to see what the problem is here. Is it that your query takes 460ms, and you need it to be quicker? Or is it something else? It would help to have some example code. Can you make a test case which reproduces te problem, that you could share? > For comparison, I have collected the SQL statements in a file with > PREPARE ... and DEALLOCATE for _every_ select and then run this file > through psql. This takes 2s! If all you are doing is preparing and deallocating - i.e. not executing - then that will be very quick, because the queries are never executed. Alistair ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ANNOUNCE: vacuum-cairo: a cairo frontend to vacuumfor live Haskell data visualization
2009/3/31 Peter Verswyvelen : > Maybe GHCi has a bug when it comes to DLL lookup. > I had an application that worked fine when compiled with GHC, but failed > with GHCi (libglew.dll not found) > I used procmon to monitor which files the GHC* processes searched, and it > seemed that the compiled version looked for libglew32.dll, while GHCi was > looking for libglew.dll > Since this only happened with our own wrapper project, I thought we made a > mistake, but maybe you could also use procmon to figure out what GHCi is > doing, it might be a bug. ghci has a custom linker which behaves differently from gnu ld, which is what ghc uses. I don't recall the exact details (if I ever knew them), just that it differs. So something that works with ghc won't necessarily do so with ghci. Alistair ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Problem using #define in .hsc files
2009/3/29 Johan Tibell :
>
> foreign import CALLCONV unsafe "send"
> c_send :: CInt -> Ptr a -> CSize -> CInt -> IO CInt
>
> Compiling results in:
>
> parse error on input `CALLCONV'
This is what we use in Takusen's Database.ODBC.OdbcFunctions.hsc:
#ifdef mingw32_HOST_OS
#let CALLCONV = "stdcall"
#else
#let CALLCONV = "ccall"
#endif
foreign import #{CALLCONV} unsafe "sql.h SQLAllocHandle" sqlAllocHandle ::
SqlHandleType -> Handle -> Ptr Handle -> IO SqlReturn
Alistair
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Re: [Haskell-cafe] examples for error handling in takusen?
2009/3/14 Gü?nther Schmidt : > Hi, > > can someone please point me to error handling examples with takusen? > > I try to run a piece of code with takusen but just get the very sparse > "Database.InternalEnumerator.DBException Hello Günther, We use dynamic exceptions in Takusen, which is why you don't get much useful information when an exception is thrown. We will include the new extensible-exceptions code in the next release, so once that it done perhaps we can change the way we do exceptions so that you get better messages by default. There are some basic exception handling functions in Database.Enumerator which should help. Firstly, you need to add an exception handler with catchDB. Then you can choose to ignore the error, report it, or re-raise it (see basicDBExceptionReporter and reportRethrow). Also, the DBException constructors are exported, so you can pattern match on it to extract more information, like SqlState, error number, and error message. Alistair ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Can this be done?
2009/2/11 Cristiano Paris : > I wonder whether this can be done in Haskell (see muleherd's comment): > > http://www.reddit.com/r/programming/comments/7wi7s/how_continuationbased_web_frameworks_work/ WASH did/does something similar. You can certainly write applications in a similar, workflow-ish style (rather than like a state machine). Alistair ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: haddock-2.3.0 literate comments discarded from .lhs input
2009/2/6 Duncan Coutts : > > Yes, against my better judgement the code in Cabal for haddock-2.x does > not run cpp or unliting like it does for haddock-0.x. Instead it assumes > that haddock-2.x will do all the cpp and unliting itself. Obviously this > mean the special unliting mode that Cabal provides is not usable with > haddock-2.x. > > The solution is to do the pre-processing the same for haddock-0.x and > 2.x. Generally the haddock code in Cabal is a horrible inconsistent > mess. I believe Andrea Vezzosi has been looking at rewriting it, which > is good news. In Distribution.Simple.Haddock, in the haddock function we have: withLib pkg_descr () $ \lib -> do let bi = libBuildInfo lib modules = PD.exposedModules lib ++ otherModules bi inFiles <- getLibSourceFiles lbi lib unless isVersion2 $ mockAll bi inFiles So I guess the easiest thing to do right now is remove the "unless isVersion2 $" . I'm testing this at the moment, so when I get it working (or not) I'll let you know, and maybe send a patch. Alistair ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: haddock-2.3.0 literate comments discarded from .lhs input
>> [1 of 1] Compiling Test.Fail( Test\Fail.hs, Test\Fail.o ) >> >> Test\Fail.hs:11:26: >>Can't make a derived instance of `Typeable Fail' >> (You need -XDeriveDataTypeable to derive an instance for this class) >>In the data type declaration for `Fail' > > Are you processing the above module but it is called Test.Fail in > reality? Have you stripped out a deriving statement from the example > above? I'm very confused by this message :) Sorry, my mistake. I pasted the error message from a different problem. This is the error I get from haddock: C:\bayleya\eclipse\workspace\takusen\src>haddock -h --odir=doc Test/Haddock.lhs Cannot find documentation for: $named_block Alistair ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] haddock-2.3.0 literate comments discarded from .lhs input
I have this test case for Haddock (2.3.0): -- | Module : Test.Haddock Copyright : (c) 2009 Alistair Bayley License : BSD-style Maintainer : alist...@abayley.org Stability : stable Portability : portable Test case for Haddock. > module Test.Haddock > ( > -- $named_block > Fail(..) > ) > where > data Fail = Fail | Succeed $named_block This is some hadock documentation. -- This fails with: [1 of 1] Compiling Test.Fail( Test\Fail.hs, Test\Fail.o ) Test\Fail.hs:11:26: Can't make a derived instance of `Typeable Fail' (You need -XDeriveDataTypeable to derive an instance for this class) In the data type declaration for `Fail' If I manually unlit, then Haddock is happy: -- -- | -- Module : Test.Haddock2 -- Copyright : (c) 2009 Alistair Bayley -- License : BSD-style -- Maintainer : alist...@abayley.org -- Stability : stable -- Portability : portable -- -- Test case for Haddock. module Test.Haddock2 ( -- $named_block Fail(..) ) where data Fail = Fail | Succeed -- $named_block -- -- This is some hadock documentation. -- so it looks as though it's discarding the literate comments. Is this intended? I was under the impression that because it used the ghc parser, it could now properly handle .lhs input. Ona related note, we have a nice unlitter in cabal that would preserve these comments before invoking haddock. Is this still used with haddock2, or does it now assume haddock2 will do the right thing? Alistair ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Elegant & powerful replacement for CSS
2009/2/3 Peter Verswyvelen : > Isn't CSS about giving a "style" to the "views" in the model-view-controller > paradigm? So basically it is a way to change the look of a user interface, > without having to change the user interface definition itself. In theory CSS separates content from presentation. In reality it looks like it isn't really powerful enough. Serendipitously, this rant popped up on reddit recently: http://www.flownet.com/ron/css-rant.html Summary: CSS's failures mean that the rendering of a page depends on the order of elements in the content. We have CleverCSS: a little less ambitious than Conal and Jeff imagined, I think, but still an improvement over raw CSS: http://sandbox.pocoo.org/clevercss-hs/ Alistair ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Takusen 0.8.3 install problems
>> > You can probably just remove the Setup.lhs and build with defaults >> > (we're doing that at galois, we use Takusen). >> > >> > -- Don I'm surprised this works, unless you also change the imports of Control.Exception to Control.OldException. The new exception module is part of the reason it's taking me a while to port to 6.10.1. Nearly there though; only the haddock failures to fix and then we can release. Alistair ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] haddock-2.3.0 error: file name does not match module name
> This has been reported before:
>
> http://trac.haskell.org/haddock/ticket/73#comment:4
>
> Not sure what's going on yet. If anyone's got a minimal test-case,
> that'd be great.
This is what fails for me (in Test/Fail.hs):
{- # LANGUAGE CPP #-}
module Test.Fail
I've added this to the trac ticket. Note the space between {- and #.
Alistair
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Re: [Haskell-cafe] Re: databases in Haskell & type-safety
2009/1/30 guenni68 : > Hi Alistair, > > yes, please, pretty please do! > > I really am desparate, I'm running into so much trouble because I have > to export to MS-Access and I'm a little out of luck with HDBC. HDBC > works like a charm > unless you have to use MS-Access. Hmm... it's not likely you'll have much success with Takusen either, as you will also have to use the ODBC bindings for MS Access, and I have not tested this combination. Perhaps you can consider an alternative route for export, like CSV? Alistair ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: databases in Haskell & type-safety
> I recently got an email back from Alstair Bayley who is one of the > Takusen authors, and they said they are preparing a GHC 6.10 release > (I was *not* the only person to submit a patch for ghc 6.10 building) > but it may take a little while. You might want to get in contact with > Alstair and ask what the current progress is. I've got it building (tests pass etc) but the haddock docs won't build at present (with ghc-6.10.1). I want to get these little problems sorted out before I package up the next release. If you're desperate then I could push what I have so far into the repo and you could build from that. Alistair ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] haddock-2.3.0 error: file name does not match module name
2009/1/29 Matthijs Kooijman : >> I assume that it's procesing file Database.Enumerator.lhs when it >> emits this, but I'm puzzled because the module name in >> Database.Enumerator.lhs is certainly Database.Enumerator, and not >> Main. > Any chance the module statement in the file is wrong? I think I remember > seeing this error once when I accidentally typed Module instead of module. > Apparently ghc assumes "Main" when there is no valid module statement. It's not this, but it certainly looks like something similar is confusing haddock. Alistair ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] haddock-2.3.0 error: file name does not match module name
I'm getting an error when I run setup haddock-2.3.0 on the Takusen src: haddock.exe: File name does not match module name: Saw: `Main' Expected: `Database.Enumerator' I assume that it's procesing file Database.Enumerator.lhs when it emits this, but I'm puzzled because the module name in Database.Enumerator.lhs is certainly Database.Enumerator, and not Main. Or am I looking in the wrong place? Alistair ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] ANN: Takusen 0.8.3
Changes since 0.8.1 (I put 0.8.2 up on hackage with an error in Setup.hs, so it's been skipped): - ODBC support: datetime marshalling is improved. For bind parameters this uses the timestamp struct for most back-ends, but String for MS SQL Server because populating the timestamp struct always failed. - more Cabal improvements: now uses configurations, so the Setup.hs script should be both simpler and more robust. Requires Cabal >= 1.4. Oracle backend on Linux should build nicely. - bug fix for a resource leak if an exception was thrown when initiating a query (the Statement handle was not closed). - some basic result-set validation against the iteratee: if you try to fetch a column that is not in the result-set, an error is thrown (rather than garbage returned). The release bundle: http://hackage.haskell.org/packages/archive/Takusen/0.8.3/Takusen-0.8.3.tar.gz The latest code: darcs get http://darcs.haskell.org/takusen Docs: http://darcs.haskell.org/takusen/doc/html/index.html A comprehensive description of API usage can be found in the documentation for module Database.Enumerator (look for the Usage section): http://darcs.haskell.org/takusen/doc/html/Database-Enumerator.html Future plans: - Output bind-parameters and multiple-result sets for ODBC - FreeTDS backend (Sybase and MS Sql Server) - support for Blobs and Clobs For those of you unfamiliar with Takusen, here is our HCAR blurb: Takusen is a DBMS access library. Like HSQL and HDBC, we support arbitrary SQL statements (currently strings, extensible to anything that can be converted to a string). Takusen's 'unique-selling-point' is safety and efficiency. We statically ensure all acquired database resources - such as cursors, connection and statement handles - are released, exactly once, at predictable times. Takusen can avoid loading the whole result set in memory, and so can handle queries returning millions of rows in constant space. Takusen also supports automatic marshalling and unmarshalling of results and query parameters. These benefits come from the design of query result processing around a left-fold enumerator. Currently we fully support ODBC, Oracle, Sqlite, and PostgreSQL. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] The state of database libraries
2008/7/4 Chris Eidhof <[EMAIL PROTECTED]>: > > I'm figuring out how to do databases in Haskell (on OS X). So far, I've tried > the following approaches: > > 1. hdbc. I'd like to connect to MySQL, so I need the ODBC backend. I couldn't > get this to work under OS X, while I installed myodbc, which seems to be > broken. > > 2. hsql. The packages on hackage don't compile, so I grabbed the darcs > version. Bummer, dude. The only database library that directly supports MySQL is HSQL. If you want to use another library, you'll have to get the ODBC MySQL backend working. Alistair ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Access to Oracle database from Haskell
>> Yes... I've had a quick look at the instant client packages. The SDK >> zip just puts the headers under instantclient_10_2/sdk/include (which >> is still not $ORACLE_HOME/rdbms/public, but c'est la vie). So it looks >> like the .rpm puts them somewhere completely different: >> /usr/include/oracle/10.2.0.4/client. Do you also have >> $ORACLE_HOME/sdk/include, with headers in? > > No, in ORACLE_HOME there is only 'bin' and 'lib'. I haven't found a way to detect where headers are installed, so I propose that the Setup.hs assumes $ORACLE_HOME/rdbms/public (for Unix), and you can add more with --extra-include-dirs=... . What do you think? Alistair ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Access to Oracle database from Haskell
2008/6/26 Henning Thielemann <[EMAIL PROTECTED]>:
>
>> Do you need to say -lclntsh when you use ghc to compile?
>
> Ah, I see, I must run both GHCi and GHC with -package Takusen and everything
> is fine.
This still doesn't seem right. Both ghci and ghc --make should
automatically link the package. The only time you should need to use
-package is in ghc "batch" mode i.e. ghc sans --make.
> configOracle verbose buildtools = do
> if not (sqlplusProgram `isElem` buildtools)
> then return Nothing
> else do
> path <- getEnv "ORACLE_HOME"
> info verbose ("Using Oracle: " ++ path)
> let (libDir, includeDir) =
> if isWindows
> then ("bin", "oci/include")
> else ("lib", "/usr/include/oracle/10.2.0.4/client")
> makeConfig path libDir includeDir
>
> This is obviously a hack. We should get the Oracle include path from the
> user, maybe via another environment variable or a custom Cabal option.
Yes... I've had a quick look at the instant client packages. The SDK
zip just puts the headers under instantclient_10_2/sdk/include (which
is still not $ORACLE_HOME/rdbms/public, but c'est la vie). So it looks
like the .rpm puts them somewhere completely different:
/usr/include/oracle/10.2.0.4/client. Do you also have
$ORACLE_HOME/sdk/include, with headers in?
Alistair
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Re: [Haskell-cafe] Access to Oracle database from Haskell
> Now I can start GHCi with the example program you gave me. However I have to > start with -lclntsh, otherwise symbol OCIEnvCreate cannot by found. > I thought I do not need this option, because the installed Takusen package > contains the library name: > > $ grep clntsh dist/installed-pkg-config > extra-libraries: clntsh clntsh > > I wonder why it appears twice, because in dist/setup-config it exists > only once: > extraLibs = ["clntsh"] Yes, puzzling. I don't know why you need to say -lclntsh, because that's the point of all of this Setup shenanigans: to get things set up so that ghci works nicely. That's why we have flags that expose/hide modules in the API: ghci has a custom linker, and this tries to link everything in the library, and of course this fails if you don't have the .ddl/.so installed for a particular backend. ghc uses gnu ld to link, and this does not try to link unused modules, so this works fine with the entire library API compiled. Do you need to say -lclntsh when you use ghc to compile? > Next step is to fetch real data from the database. But now I encounter new > problems. If I write a real 'select' statement I get at best: > > Unexpected null in row 1, column 1. > *** Exception: (unknown) This looks like you are fetching a null value back with an iteratee that does not expect nulls. We use Maybe to specify that a column in the result-set can be null e.g. iter :: Int -> Maybe Int -> Maybe String -> IterAct [(Int, Maybe Int, Maybe String)] The first column must never contain null. If it does then you get the "Unexpected null" exception. > and at worst: > > 50001752 > *** glibc detected *** /usr/lib/ghc-6.8.2/ghc-6.8.2: free(): invalid > pointer: 0x08d10065 *** > === Backtrace: = If this continues, can you provide a test case for me? Alistair ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Access to Oracle database from Haskell
> I'll have to change the way that Setup.hs tries to find $ORACLE_HOME.
> Using getEnv would be a much better idea. I don't recall why I didn't
> use it before; perhaps it's not always set on Windows installations.
Try this version of configOracle in Setup.hs:
configOracle verbose buildtools = do
if not (sqlplusProgram `isElem` buildtools)
then return Nothing
else do
path <- getEnv "ORACLE_HOME"
info verbose ("Using Oracle: " ++ path)
makeConfig path libDir "oci/include"
where libDir = if isWindows then "bin" else "lib"
You'll also need to add this import:
import System.Environment (getEnv)
I always used to get the "Using..." messages, but now it seems I need to say:
$ setup configure -v -foracle
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Re: [Haskell-cafe] Access to Oracle database from Haskell
>> $ ll $ORACLE_HOME/lib >> ... >> I assume that libociei.so is the library I need. > > Actually it's libclntsh.so. You need to change the oracle section in > Takusen.cabal to this: Another difference between Windows and Linux Oracle installations is that the client libs are in $ORACLE_HOME/lib on Linux, but in $ORACLE_HOME/bin on Windows. The Setup.hs script has the Windows case baked in. You should change the configOracle function like so: configOracle verbose buildtools = createConfigByFindingExe verbose buildtools "Oracle" sqlplusProgram parentFolder oracleLibDir "oci/include" -- location of OCI client library differs between Windows and Unix where oracleLibDir = if isWindows then "bin" else "lib" Alistair ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Access to Oracle database from Haskell
>> 2008/6/24 Henning Thielemann <[EMAIL PROTECTED]>: >>> >> When you run configure, you should get output that says: >> Using Oracle: >> >> What is ? > > I don't get these questions. Sorry. I was really asking (not very clearly): what is the output from "runhaskell Setup.hs configure -foracle" ? You've answered that below. > Ah, I must have set ORACLE_HOME for the Takusen installation ... should be > documented. However in my case, this doesn't change the path used by > Takusen's Setup/install. Well, you don't actually need it set for the Takusen install (it doesn''t use it). But $ORACLE_HOME/bin should be in your path. And it needs to contain the executable sqlplus. Can you run sqlplus? It looks as though you don't have it. If sqlplus is not in my path then I get this error in the configure step, because I have specified sqlplus as a buildtool in Takusen.cabal: > setup configure -foracle Configuring Takusen-0.8.2... setup: sqlplus is required but it could not be found. Note: sqlplus isn't really needed to build; this is just a validation step, to check you have $ORACLE_HOME/bin in your path. > $ echo $ORACLE_HOME > /usr/lib/oracle/10.2.0.4/client > $ ls $ORACLE_HOME > bin lib > $ ll $ORACLE_HOME/lib > ... > I assume that libociei.so is the library I need. Actually it's libclntsh.so. You need to change the oracle section in Takusen.cabal to this: If flag(oracle) Exposed-modules: Database.Oracle.Enumerator , Database.Oracle.OCIConstants , Database.Oracle.OCIFunctions Build-Tools: sqlplus If os(windows) Extra-Libraries: oci Else Extra-Libraries: clntsh Your $ORACLE_HOME installation looks fairly normal, if somewhat minimal. I would normally expect to see sqlplus, and maybe some other executables, like tnsping. And a folder $ORACLE_HOME/oci/include, which contains the OCI header files. Perhaps you could also install the sqplus and SDK packages, as Lanny Ripple suggested, although I suspect they may not be strictly necessary, as you can apparently successfully compile, as evidenced below. > $ runhaskell Setup.hs configure --user -f oracle > Configuring Takusen-0.8.2... Here, I would expect to see "Using Oracle: /usr/lib/oracle/10.2.0.4/client" After setup configure you can say: $ runhaskell Setup.hs register --gen-pkg-config and then take a look at the generated Takusen-0.8.2.conf. Check the library-dirs and include-dirs fields. Alistair ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Access to Oracle database from Haskell
2008/6/24 Henning Thielemann <[EMAIL PROTECTED]>:
>
> (I remain on the list in order to fill the archive with information, others
> may need, too.)
As you wish.
> (Btw. Takusen should be split into
> several packages for all database backends because Cabal flags must not
> influence the package interface.)
I don't understand this (cabal flags must not influence package
interface). I thought that was the point of cabal flags? I wanted to
have a single package installation, and this seems like the best way.
> But on installation Cabal complains about missing /usr/oci directory.
When you run configure, you should get output that says:
Using Oracle:
What is ?
The Setup.hs assumes the entire Oracle installation is under a single
root folder ($ORACLE_HOME); is this not true on Linux? If not, then we
will have to find some other way of locating the bin and include
folders. Perhaps we can do something like the Postgres installation,
where there is a program you can run which will print the include and
lib folders. That may mean a little hacking on Setup.hs, but there's
already a good example there for Postgres.
> Once I will get Takusen running with OCI - how would I use it? Is there a
> minimal example which connects to an Oracle database, performing a very
> simple query?
There's an example in the README.txt, which I've tweaked here for Oracle:
{-# OPTIONS -fglasgow-exts #-}
{-# OPTIONS -fallow-overlapping-instances #-}
module Main where
import Database.Oracle.Enumerator
import Control.Monad.Trans (liftIO)
main = flip catchDB reportRethrow $
withSession (connect "user" "pswd" "dbname") (do
let iter (s::String) (_::String) = result s
result <- doQuery (sql "select 'Hello world.' from dual") iter ""
liftIO (putStrLn result)
)
Alistair
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Re: [Haskell-cafe] Access to Oracle database from Haskell
2008/6/20 Alistair Bayley <[EMAIL PROTECTED]>: >> Is there a way of accessing a remote Oracle database by one of the common >> Haskell database interfaces (HaskellDB, Takusen, etc.) ? I tried to get >> unixODBC and Oracle's Instant Client running on a Linux machine, but I'm >> trapped in the notorious error: > > Takusen's Oracle backend uses the Oracle Call Interface (OCI) library > directly. I think most Oracle client drivers (ODBC, ADO.Net, etc) use > the OCI. I don't know what the Oracle Instant Client is; I'll assume > that it includes an oci.so or liboci.so. On Windows, with which I am > most familiar, the Oracle client software is all installed in > $ORACLE_HOME, and the OCI library is $ORACLE_HOME/bin/oci.dll. If you > can locate that, then you ought to be able to use Takusen with it. Having just taken a closer took at what Oracle Instant Client is, I suspect that you might have some trouble getting Takusen to compile against it. The Instant Client lacks header files, while Takusen's FFI imports specify oci.h. I don't know what happens if ghc can't find the header files. Oracle do state that the Instant Client is for deployment only; developers (that means you) will need the full client installation. Another problem is that the Oracle installation process assumes that, for all platforms, the library is called oci i.e. the linker option -loci is used. For Unix clients, the OCI library seems to be libclnstsh.so, so I guess it should pass -lclnstsh. This highlights the lack of testing on non-Windows platforms. If you'd like to help get this working better, perhaps we can discuss off-list. Alistair ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Access to Oracle database from Haskell
> Is there a way of accessing a remote Oracle database by one of the common > Haskell database interfaces (HaskellDB, Takusen, etc.) ? I tried to get > unixODBC and Oracle's Instant Client running on a Linux machine, but I'm > trapped in the notorious error: Takusen's Oracle backend uses the Oracle Call Interface (OCI) library directly. I think most Oracle client drivers (ODBC, ADO.Net, etc) use the OCI. I don't know what the Oracle Instant Client is; I'll assume that it includes an oci.so or liboci.so. On Windows, with which I am most familiar, the Oracle client software is all installed in $ORACLE_HOME, and the OCI library is $ORACLE_HOME/bin/oci.dll. If you can locate that, then you ought to be able to use Takusen with it. Alistair ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] What to do when GHC works, RUNGHC fails
2008/5/23 Peter Verswyvelen <[EMAIL PROTECTED]>: > So it seems the GHCi linker is not using the metadata in the library file > correctly? The libpng.dll.a library file clearly contains a reference to > libpng3.dll, and I guess since GHC is using the GCC linker, this works fine, > but GHCi most likely has its own linker? > > If this is correct, we should file a bug report? This seems to be the same bug: http://hackage.haskell.org/trac/ghc/ticket/1883 The ghci linker is a custom one (AFAIK) and is "different" from GNU ld. That's a feature, not a bug :-) GNU ld, for example, can find either of libxxx.dll or xxx.dll if you say -lxxx. See this ticket for another difference between ghci and GNU ld (ghci's linker tries to link _all_ symbols in the library archive, rather than just the modules that you're using): http://hackage.haskell.org/trac/ghc/ticket/1477 Alistair ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] What to do when GHC works, RUNGHC fails
2008/5/22 Peter Verswyvelen <[EMAIL PROTECTED]>: > The first thing I noticed is that RUNGHC looks for a DLL called "png.dll" > (which it doesn't find and then bails out with an error), while the > executable build with GHC uses the correct "libpng3.dll". When I rename the > libpng3.dll into png.dll, RUNGHC goes a bit further but then fails with an > "unknown symbol". Obviously I did something wrong in my Cabal script, but I > have no idea what it is. > > There seems to be a big difference when it comes to linking between of GHCi > and GHC . Any guidelines on what to do in cases like the one above? We had a similar problem with Takusen and ghci on Windows, where the PostgreSQL client dll is called libpq.dll, rather than pq.dll. We also solved it by copying pq.dll to libpq.dll. The extra-libs option is pq, rather than libpq. That fixed it for us, so I don't know why yours is still failing. Perhaps you can post a link to the src? Alistair ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Std lib equivalent for liftM concat . sequence
A couple of days ago I had need for: > concatM :: Monad m => [m [a]] -> m [a] > concatM = liftM concat . sequence but found no such thing in the std libs, except perhaps for msum (I don't want to add instances for MonadPlus. Should I have to?). Have I missed something trivial? Alistair ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] ANN: Takusen 0.8.1
http://hackage.haskell.org/cgi-bin/hackage-scripts/package/Takusen-0.8.1 This is a fairly minor bugfix release. although there are some API changes. Mainly, we've re-exported a lot of the types from Database.InternalEnumerator in Database.Enumerator. This will hopefully address a common complaint that it's impossible to always write type sigs for functions doing database stuff. We've also tidied up some of the exports; there was stuff exposed that shouldn't have been. There's an outstanding bug involving datetime parameter marshaling in ODBC, which I have not had time to resolve (parameters after the datetime parameter get mangled somehow). I will be on holiday for a few weeks, so this will not be addressed by me for some time. Caveat user. The test suite highlights it, should someone else feel sufficiently motivated; I've been testing against PostgreSQL. Alistair ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Need Cabal/library building help for windows
On 17/03/2008, Felix Martini <[EMAIL PROTECTED]> wrote: > Ryan Ingram wrote: > > For reference, I'm using GHC6.8.1 on WinXP. > > > setup.hs: ld is required but it could not be found. > > I did have the same issue with GHC 6.8.1 on Windows. It is fixed in > version 6.8.2. > > http://haskell.org/ghc/download_ghc_682.html#windows Upgrading GHC to fix this seems a little extreme. You can just add gcc-lib (i.e. C:\ghc\ghc-6.8.1\gcc-lib) to your path. Alistair ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: ANN: Takusen 0.8
> Changes since 0.6: > > - ODBC support. This still has a few gaps (and probably bugs and rough > edges) >but should be fairly usable. Doh! I had also meant to make a request: the ODBC code (and Setup.hs configuration) is only tested under Windows (XP). We'd love for people to test on *nix platforms and fill in the missing bits in the Setup script. Alistair ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] ANN: Takusen 0.8
Oleg and I are pleased to announce the release of Takusen 0.8. (Don Stewart did an interim 0.7 release for us a few weeks ago, and added us to Hackage. This release is a tidy-up of some loose ends, and some bug fixes. Hence, I've summarise the changes since the 0.6 release.) Changes since 0.6: - ODBC support. This still has a few gaps (and probably bugs and rough edges) but should be fairly usable. - support for reusable/persistent sessions, so you can hang onto the connection object between invocations of withSession (this was in release 0.6 but omitted from the release notes). - improvements to the Cabal Setup scripts, which should give better experiences for ghc-6.4, ghc-6.6, and ghc-6.8. The (eventual) 1.4 release of Cabal should be able to build our haddock docs, too. - improved UTF8 decoder (marshals directly from buffer). The release bundle: http://hackage.haskell.org/packages/archive/Takusen/0.8/Takusen-0.8.tar.gz The latest code: darcs get http://darcs.haskell.org/takusen Docs: http://darcs.haskell.org/takusen/doc/html/index.html A comprehensive description of API usage can be found in the documentation for module Database.Enumerator (look for the Usage section): http://darcs.haskell.org/takusen/doc/html/Database-Enumerator.html Future plans: - FreeTDS backend (Sybase and MS Sql Server) - support for Blobs and Clobs For those of you unfamiliar with Takusen, here is our HCAR blurb: Takusen is a library for accessing DBMS's. Like HSQL, we support arbitrary SQL statements (currently strings, extensible to anything that can be converted to a string). Takusen's `unique-selling-point' is safety and efficiency. We statically ensure all acquired database resources - such as cursors, connection and statement handles - are released, exactly once, at predictable times. Takusen can avoid loading the whole result set in memory, and so can handle queries returning millions of rows in constant space. Takusen also supports automatic marshalling and unmarshalling of results and query parameters. These benefits come from the design of query result processing around a left-fold enumerator. Currently we fully support ODBC, Oracle, Sqlite, and PostgreSQL. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] haddock as a markdown preprocessor
On 21/02/2008, Duncan Coutts <[EMAIL PROTECTED]> wrote: > > To be honest I like the fact that haddock's markup is really simple and > perhaps somewhat restrictive. A great improvement though would be to > make it easy to extract the docs from haddock in a nice format so that > the could be re-used in other contexts rather than just generating html > api documentation. Haddock does have support for multiple backends, > someone just needs to define and write a generic backend that spits out > the info that haddock gathers in a machine readable format. I have probably misunderstood both of you, but I think that Conal proposed that Haddock *input* syntax is largely unchanged; Haddock should be able to *output* markdown, for consumption by pandoc. (Which I think is also what you're suggesting.) Alistair ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ANN: Leksah 0.1 - Haskell IDE written in Haskell
On 14/02/2008, Alistair Bayley <[EMAIL PROTECTED]> wrote: > > src/IDE/Utils/File.hs:161:33: > Couldn't match expected type `Either String String' >against inferred type `String' Never mind; I've just realised this is because I have the latest dev version of Cabal installed. Alistair ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ANN: Leksah 0.1 - Haskell IDE written in Haskell
> Leksah is written by me and published under a GPL-2 license. > Leksah can be optained via Hackage: http://hackage.haskell.org/ > Darcs development repository: http://code.haskell.org/leksah I just downloaded this from hackage and went through the usual Cabal ritual. The build fails with [16 of 41] Compiling IDE.Utils.File ( src/IDE/Utils/File.hs, dist\build\leksah\leksah-tmp/IDE/Utils/File.o ) src/IDE/Utils/File.hs:161:33: Couldn't match expected type `Either String String' against inferred type `String' In the expression: if takeExtension fp == ".lhs" then unlit fp str else str In the definition of `str'': str' = if takeExtension fp == ".lhs" then unlit fp str else str In the expression: if exists then do str <- readFile fp let str' = ... let parseRes = ... else return Nothing Would I be better off getting straight from the darcs repo? Alistair ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: code.haskell.org vs darcs.haskell.org (was [Haskell-cafe] Enterprise Haskell AMQP library)
On 29/01/2008, Henning Thielemann <[EMAIL PROTECTED]> wrote: > > Thanks for the clarification! I added it to > http://www.haskell.org/haskellwiki/Haskell.org_domain > Can you insert the link to the web-submission system? I've done this. I also tried to request an account on code.haskell.org, but the server complains about my public key: 500 Internal Server Error SSH key looks incorrect I pasted the key from this path (I use Putty and Pagaent on WinXP): C:\bayleya\putty\putty\id_dsa_pub.txt This folder also contains id_dsa.ppk (that's what Pagaent uses), which contains the same key, and also the private bit. The public key looks like this: BEGIN SSH2 PUBLIC KEY Comment: "dsa-key-20040309" B3NzaC1kc3MAAACBAKs9yeNP35s4rSBDlJKQCC1nemVGd0zQAROFKeziCOGm W5zrOSga/U/Cfa2rIM8Ko/9QmjNCJKsJioC5OTZMwOF0+zBWFCNN73z5+Dz/+PL+ Xw== END SSH2 PUBLIC KEY and this is what I've pasted into the form. I've also tried trimming it (removing the -- BEGIN and END, and the Comment) but no joy. Is this the right thing to put into the form? If not, where can I find it? Thanks, Alistair ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Data.Generics: how do I get the type name of a value?
On 14/12/2007, Neil Mitchell <[EMAIL PROTECTED]> wrote: > > > http://haskell.org/hoogle/?q=typeOf > > Another great thing is that this bit also works in Hugs, while the > Data.Generics stuff is GHC only. Great, thanks. Didn't occur to me to look further up the class hierarchy :-) Alistair ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Data.Generics: how do I get the type name of a value?
I've been learning/playing with Data.Generics a bit, and have a how-to
question...
If I say
> dataTypeOf ""
then I get
> DataType {tycon = "Prelude.[]", datarep = AlgRep [[],(:)]}
No surprises there. But I'd really like to know that I have a String,
or [Char]. How do I get the name of the concrete type that the list
contains? Is that a reasonable thing to ask for?
I can say:
> gmapQ dataTypeOf "a"
to get:
> [ DataType {tycon = "Prelude.Char", datarep = StringRep}
> , DataType {tycon = "Prelude.[]", datarep = AlgRep [[],(:)]}
> ]
But if I say:
> gmapQ dataTypeOf ""
I get:
> []
which makes sense when you consider the stucture of the List ADT, but
doesn't help me determine the type of the value.
Alistair
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Re: [Haskell-cafe] Why is this strict in its arguments?
> Use of isNothing and fromJust and a cascade of ifs is generally a poor > sign, much better to use case: > > findAllPath pred (Branch lf r rt) > | pred r = > case (findAllPath pred lf,findAllPath pred rt) of >(Nothing,Nothing) -> Nothing >(Nothing,Just rtpaths) -> Just (map (r:) rtpaths) >(Just lfpaths,Nothing) -> Just (map (r:) lfpaths) >(Just lfpaths,Just rtpaths) -> Just (map (r:) $ rtpaths ++ > lfpaths) > | otherwise = Nothing > > the general pattern is : replace isNothing with a case match on Nothing, > replace fromJust with a case match on Just, don't be afraid to case two > expressions at once. Nested Maybe cases put me in mind of the Maybe monad. Although in this case it''s not trivial; we also need to involve the Maybe [a] instance of Data.Monoid too (for the mappend function). I do wonder if I'm abusing the monadic instances of Maybe though; is this really any clearer than Jules' code? (BTW, this has probably come up before, but wouldn't it be a little bit nicer if "when" returned mzero rather than () in the "do nothing" case?) > when' :: MonadPlus m => Bool -> m a -> m a > when' pred action = if pred then action else mzero > > findAllPath :: (a -> Bool) -> (BTree a) -> Maybe [[a]] > findAllPath pred (Leaf l) = when' (pred l) (return [[l]]) > findAllPath pred (Branch lf r rt) = > when' (pred r) $ do > x <- mappend (findAllPath pred lf) (findAllPath pred rt) > return (map (r:) x) Alistair ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Cabal and DB packages
On 25/11/2007, Thomas Schilling <[EMAIL PROTECTED]> wrote: > On Sun, 2007-11-25 at 18:49 +0100, manu wrote: > > Hello, > > > > I'm trying to do something that should be fairly simple, installing > > some DB package so I can use MySQL or SQLite. > > > > with Takusen : > > > > $ runhaskell Setup.hs configure > > > > Setup.hs:26:7: > > Could not find module `Distribution.Program': > >Use -v to see a list of the files searched for. > > > > I give up... > > > > > > That means that Takusen requires an older Cabal. I'd have to look at > the code to see how hard it would be to fix this. Um, yes. We haven't tested Takusen with ghc-6.8.1 yet, but it's on the list... Our Setup.hs is a bit involved at present, and soon I hope to simplify it quite a bit. There's a load of stuff in there just to get it to build Haddock docs, which will be gone soon. Alistair ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] New slogan for haskell.org
On 08/10/2007, Henning Thielemann <[EMAIL PROTECTED]> wrote: > > You cannot turn any programmer into a disciplined programmer just by > giving him a well designed language. I you try so, they will not like to > use that language, will leave that language as soon as possible or they > try to adapt the language to their style of programming. Well, I wasn't suggesting you'll create great programmers overnight, but you might expect that their appreciation of good design might improve after some Haskell exposure. Also, Haskell simply doesn't support some of the things that are common causes of errors in the enterprisey-language world. I recall reading something about one of the most common causes of errors in novice programs being type errors (presumably, once they'd got the program to compile i.e. there were no syntactic errors). And I'm under the (possibly mistaken) impression that some of the common errors non-novice programmers make are aliasing bugs, and/or use of global variables. Does anyone have references to studies confirming (or refuting) this? > People who are used to weak typing will use a type like >data Number = Int Int | Float Float | ... > for numbers, or even String for everything, they will use numbers, where > enumerations are more appropriate and so on. I think that the ease with which you can create a new type in Haskell (and derive useful classes like Enum, Show, etc) makes it more likely that a programmer will use an appropriate domain-specific type, rather than just reuse String, Int, or Float. > In my experience only the other way round works: Let people use C, Perl > and Python until they find their programs unmaintainable. Then they will > become interested in style and discipline and programming languages which > _support_ good style. Well, yes. Or have them learn Haskell, and *then* C/C#/C++/Java/Perl etc, and see if the experience for those languages is as good. I like to think they'll come running back to Haskell's warm bosom. Alistair ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] New slogan for haskell.org
On 05/10/2007, Andrew Coppin <[EMAIL PROTECTED]> wrote: > > > > So the question becomes: do you want to attract/seduce this kind of > > programmer? Let's assume the answer is yes :-) > > Um... that assumpion troubles me. > ... > I think if we want to get anywhere we need to look at targeting people > whom Haskell actually has something to offer. Now, if I could just > figure out who those are... :-/ And: On 05/10/2007, Jonathan Cast <[EMAIL PROTECTED]> wrote: > On Fri, 2007-10-05 at 20:19 +, Aaron Denney wrote: > > On 2007-10-05, Peter Verswyvelen <[EMAIL PROTECTED]> wrote: > > > If you want to attract more people that are inside the > > > "imperative-OO-with-nice-IDE-blob", create a great looking and > > > functional IDE. > > > > Bluntly, I don't see why the Haskell community needs those sorts of > > programmers. > > Hear, hear. At the company I work for, all the code is perl/web > development --- and we wouldn't dream of hiring one of those > programmers. I posed the question: do we want to attract this kind of programmer? My personal opinion, which some of you obviously don't share, is yes. It isn't about whether or not the Haskell community needs those sorts of programmers. It's whether or not those sorts of programmers need Haskell. For me, a large part of Haskell's attraction are the features which reflect good engineering practice: strong, static type checking; purely functional code; good FFI. It should be easier to write simple, reliable software in Haskell than in most other languages; IMO, getting the unwashed hordes to use Haskell would be a great improvement in software industry productivity. I realise that a large influx of mediocre programmers will have a negative effect on the community, but is that a reasonable price to pay? I understand that may of you love a small, intimate, high-quality community, but perhaps that will have to evolve if we really want to conquer the world. Alistair ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: Error building takusen with Cabal-1.1.6.2
> > Setup.hs:13:7:
> > Could not find module `Distribution.Compat.FilePath':
> > it is hidden (in package Cabal-1.1.6.2)
>
> This is what I did to make takusen build with ghc-6.6.1:
>
> [EMAIL PROTECTED]: .../haskell/takusen_0 > darcs whatsnew
> {
> hunk ./Setup.hs 13
> -import Distribution.Compat.FilePath (splitFileName, joinPaths)^M$
> +import System.FilePath (splitFileName, combine)^M$
> hunk ./Setup.hs 124
> - libDirs <- canonicalizePath (joinPaths path libDir)^M$
> - includeDirs <- canonicalizePath (joinPaths path includeDir)^M$
> + libDirs <- canonicalizePath (combine path libDir)^M$
> + includeDirs <- canonicalizePath (combine path includeDir)^M$
> }
>
> HTH
> Ben
I've pushed changes to the Setup scripts (and the README.txt) in the
darcs report so that it should build out-of-the-box. Just pull the
latest code.
However, I'm off on holiday (more-or-less unaccessable) for a couple
of weeks on Monday, so if I've busted it badly, I apologize in
advance.
Alistair
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Re: [Haskell-cafe] Optimising UTF8-CString -> String marshaling, plus comments on withCStringLen/peekCStringLen
Hello cafe,
(Following up on my own optimisation question, and Duncan's advice
to look at http://darcs.haskell.org/ghc/compiler/utils/Encoding.hs)
If you want to look at some existing optimised UTF8 encoding/decoding
code then take a look at the code used in GHC:
http://darcs.haskell.org/ghc/compiler/utils/Encoding.hs
Duncan
I took a look at the UTF8 decoder in GHC. This inspired me to write
one that also used unboxed types directly. Pleasingly, it goes like
a cut cat, and uses far less space than the naive version, but it's
not portable, which is a bummer.
(The docs tell me that using GHC.Exts is the "approved" way of
accessing GHC-specific extensions, but all of the useful stuff seems
to be in GHC.Prim.)
After some expriments with the simplifier, I think I have a portable
version of a direct-from-buffer decoder which seems to perform nearly
as well as one written directly against GHC primitive unboxed functions.
I'm wondering if there's anything further I can do to improve performance.
The "portable" unboxed version is within about 15% of the unboxed version
in terms of time and allocation.
Changes I made:
- added strictness "annotations" in the form of a strictness guards
that are always False
- unrolled loops (they were always short loops anyway, with a maximum
of 3 or 4 iterations)
- replaced shiftL with multiplication, because multiplication unboxes,
while shiftL doesn't.
Some things I've noticed in the simplifier output:
- the shiftL call hasn't unboxed or inlined into a call to
uncheckedShiftL#, which I would prefer.
Would this be possible if we added unchecked versions of
the shiftL/R functions to Data.Bits?
- Ptrs don't get unboxed. Why is this? Some IO monad thing?
- the chr function tests that its Int argument is less than 1114111,
before constructing the Char. It'd be nice to avoid this test.
- why does this code:
| x <= 0xF7 = remaining 3 (bAND x 0x07) xs
| otherwise = err x
turn into this
i.e. the <= turns into two identical case-branches, using eqword#
and ltword#, rather than one case-branch using leword# ?
case GHC.Prim.eqWord# a11_a2PJ __word 247 of wild25_X2SU {
GHC.Base.False ->
case GHC.Prim.ltWord# a11_a2PJ __word 247 of wild6_Xcw {
GHC.Base.False ->
GHC.Base.True ->
$wremaining_r3dD
3
(__scc {fromUTF8 main:Foreign.C.UTF8 !}
GHC.Base.I# (GHC.Prim.word2Int# (GHC.Prim.and# a11_a2PJ __word 7)))
xs_aVm
};
GHC.Base.True ->
$wremaining_r3dD
3
(__scc {fromUTF8 main:Foreign.C.UTF8 !}
GHC.Base.I# (GHC.Prim.word2Int# (GHC.Prim.and# a11_a2PJ __word 7)))
xs_aVm
};
BTW, what's the difference between the indexXxxxOffAddr# and
readXxxxOffAddr# functions in GHC.Prim? AFAICT they are equivalent,
except that the read* functions take an extra State# s parameter.
Presumably this is to thread the IO monad's RealWorld value through,
to create some sort of data dependency between the functions (and so
to ensure ordered evaluation?)
Alistair
{-# OPTIONS_GHC -fglasgow-exts #-}
-- |
-- Module : Foreign.C.UTF8
-- Copyright : (c) 2004 John Meacham, Alistair Bayley
-- License : BSD-style
-- Maintainer : [EMAIL PROTECTED]
-- Stability : experimental
-- Portability : portable
--
-- Marshall Haskell Strings to and from UTF8-encoded CStrings.
-- This module's code is inspired by John Meacham's UTF8 en- & de-coders,
-- and also those found in the HXT library (module Text.XML.HXT.DOM.Unicode).
--
-- Note that the -Len functions all return the length in bytes,
-- not Chars (this is more useful, as you are most likely to want
-- to pass the length to an FFI function, which is most likely
-- expecting the length in bytes). If you want the length in Chars,
-- well, you have the original String, so...
module Foreign.C.UTF8
( peekUTF8String, peekUTF8StringLen
, peekUTF8StringB, peekUTF8StringLenB
, newUTF8String, withUTF8String, withUTF8StringLen
, toUTF8String, fromUTF8String
, lengthUTF8, fromUTF8, toUTF8
) where
import Control.Monad (when, liftM)
import Data.Bits
import Data.Char
import Data.Word (Word8)
import Foreign.C.Types
import Foreign.C.String
import Foreign.Ptr
import Foreign.Marshal.Array
import Foreign.Storable
import GHC.Base
import GHC.Ptr (Ptr(..))
nullCChar :: CChar
nullCChar = 0
nullByte :: Word8
nullByte = 0
-- | Analogous to peekCString. Converts UTF8 CString to String.
peekUTF8String :: CString -> IO String
peekUTF8String cs = peekArray0 nullByte (castPtr cs) >>= return . fromUTF8
peekUTF8StringB :: CString -> IO String
peekUTF8StringB cs = fromUTF8Ptr0 (castPtr cs)
-- | Analogous to peekCStringLen. Converts UTF8 CString to String.
-- The resulting String will end either when @len@ bytes
-- have been converted, or when a NULL is found.
peekUTF8StringLen :: CString
Re: [Haskell-cafe] haskell -> db, on Solaris
> http://www.haskell.org/haskellwiki/Applications_and_libraries/Database_interfaces > > If you want to talk to MySQL, you have a few choices. > > HDBC has an ODBC interface that lets you use any ODBC provider, so > you'll be able to talk to both MySQL and Oracle with it. > > HaskellDB can bridge to HDBC, I believe, so that will let you do > type-safe SQL. > > There's also Takusen, which can talk to Oracle, but not MySQL. Yes, thanks. But the emphasis was on Solaris. I don't quite understand what is the common way to access databases on Solaris. Is it odbc? And how Haskell libraries connect to that? I mean, Takusen is designed to use odbc and nothing else (afaik), for example. Takusen uses OCI to talk to Oracle, so it should work on any Oracle (& GHC) platform. However, no ODBC or MySQL backend yet (I'm working on ODBC right now, but it's slow going...). I imagine that the common way to access databases on Solaris is the same as on other Unix platforms, which is probably to use the vendor's API directly. There is also http://www.unixodbc.org/, which appears to support Solaris, but I can't vouch for it from a usability perspective i.e. how hard is it to get working, and to get working with HDBC or HSQL. I'd recommend giving unixodbc + hsql/hdbc a go, and let us know of any problems. Alistair ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] sha1 implementation thats "only" 12 times slower then C
On 03/07/07, Anatoly Yakovenko <[EMAIL PROTECTED]> wrote: inlining some of the functions definitely gave me a boost, so i am about 8.5 times slower then openssl sha1sum. I dont really understand the core output, but after inlining i got a completely different profile output, i am guessing its because the cost of the inlined functions is spread to the callers. Are you using -auto, or -auto-all? Because it makes a difference to the generated core, and the extent to which inlining takes place. I've noticed that -auto permits more inlining than -auto-all, so try -auto if you can. Also, follow the advice in the GHC manual, and only export the functions you need to. This will aid both the inliner and specialiser enormously. As for reading core (well, actually simplifier output; core has less "punctuation"), these links might help: 4.16.3. How to read Core syntax http://www.haskell.org/ghc/docs/latest/html/users_guide/options-debugging.html#id3130643 (and the Encoding module has the actual rules for the Unique names) http://darcs.haskell.org/ghc/compiler/utils/Encoding.hs 6.2. Faster: producing a program that runs quicker http://www.haskell.org/ghc/docs/latest/html/users_guide/faster.html (see "How do I find out a function's strictness?") Alistair ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Building Yi (and wider Cabal stuff)
I'm trying to build Yi (from the darcs repository) to take a look at it. The README that comes with it says "it's a standard Cabal project so do what you normally do" (paraphrased slightly). The problem is that I'm not a cabal user just yet and have no idea where to go from here. The standard cabal usage is: runhaskell Setup.hs configure runhaskell Setup.hs build runhaskell Setup.hs install http://www.haskell.org/haskellwiki/How_to_install_a_Cabal_package Alistair ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Optimising UTF8-CString -> String marshaling, plus comments on withCStringLen/peekCStringLen
Simon,
Sorry for the delay on responding.
I'm using 6.6, so I'll upgrade to 6.6.1 and retest. Preusmably you're
only interested if this behaviour persists in 6.6.1. I'll check both
cases and make a test cases for them if necessary.
I've upgraded to 6.6.1 and am pleased to report that there appears to
be no difference between seq and bang-patterns in the simplifier output.
As for the other case (where a function results in two functions in the
simplifier output, which appear to be some sort of worker-wrapper pair),
a module is attached which gives this behaviour.
I compiled it with:
ghc -c UTF8.hs -O2 -prof -auto -ddump-simpl
Look for $s$wfromUTF8Ptr and $wfromUTF8Ptr.
I also notice that with -auto-all, the function readUTF8Char appears in
the simplifier output, but with -auto it is inlined into fromUTF8Ptr, and
so vanishes from the simplifier output.
Running my test case compiled with -auto seems to gives run times at about
70-80% of -auto-all, and allocation is 40% (!) of -auto-all; that's a
significant difference.
Alistair
module UTF8
( peekUTF8String, peekUTF8StringLen
) where
import Control.Monad (when, liftM)
import Data.Char
import Data.Word (Word8)
import Foreign.C.String
import Foreign.Ptr
import Foreign.Marshal.Array
import Foreign.Storable
import GHC.Base (unsafeChr)
nullByte :: Word8
nullByte = 0
peekUTF8String :: CString -> IO String
peekUTF8String cs = fromUTF8Ptr0 (castPtr cs)
peekUTF8StringLen :: CStringLen -> IO String
peekUTF8StringLen (cs, len) = fromUTF8Ptr (len-1) (castPtr cs) ""
fromUTF8Ptr0 :: Ptr Word8 -> IO String
fromUTF8Ptr0 p = do
len <- lengthArray0 nullByte p
fromUTF8Ptr (len-1) p ""
fromUTF8Ptr :: Int -> Ptr Word8 -> String -> IO String
fromUTF8Ptr bytes p acc
| () `seq` bytes `seq` p `seq` acc `seq` False = undefined
| bytes < 0 = return acc
| otherwise = do
x <- liftM fromIntegral (peekElemOff p bytes)
case () of
_ | x == 0 -> error ("fromUTF8Ptr: zero byte found in string as position " ++ show bytes)
| x <= 0x7F -> fromUTF8Ptr (bytes-1) p (unsafeChr x:acc)
| x <= 0xBF && bytes == 0 -> error "fromUTF8Ptr: surrogate at start of string"
| x <= 0xBF -> fromUTF8Ptr (bytes-1) p acc
| otherwise -> do
c <- readUTF8Char x bytes p
fromUTF8Ptr (bytes-1) p (c:acc)
readUTF8Char :: Int -> Int -> Ptr Word8 -> IO Char
readUTF8Char x offset p
| () `seq` x `seq` offset `seq` p `seq` False = undefined
| otherwise =
case () of
_ | x == 0 -> err x
| x <= 0x7F -> return (unsafeChr x)
| x <= 0xBF -> err x
| x <= 0xDF -> do
x1 <- liftM fromIntegral (peekElemOff p (offset + 1))
return (unsafeChr (
((x - 0xC0) * 64)
+ (x1 - 0x80)
))
| x <= 0xEF -> do
x1 <- liftM fromIntegral (peekElemOff p (offset + 1))
x2 <- liftM fromIntegral (peekElemOff p (offset + 2))
return (unsafeChr (
((x - 0xE0) * 4096)
+ ((x1 - 0x80) * 64)
+ (x2 - 0x80)
))
| x <= 0xF7 -> do
x1 <- liftM fromIntegral (peekElemOff p (offset + 1))
x2 <- liftM fromIntegral (peekElemOff p (offset + 2))
x3 <- liftM fromIntegral (peekElemOff p (offset + 3))
return (unsafeChr (
((x - 0xF0) * 262144)
+ ((x1 - 0x80) * 4096)
+ ((x2 - 0x80) * 64)
+ (x3 - 0x80)
))
| otherwise -> err x
where
err x = error ("readUTF8Char: illegal UTF-8 character " ++ show x)
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Re: [Haskell-cafe] Optimising UTF8-CString -> String marshaling, plus comments on withCStringLen/peekCStringLen
Simon, You're right, both versions should give the same code. Which version of GHC are you using? Both with the HEAD and with 6.6.1 I get the nice unboxed code with the `seq` version too. My test program is below. I'm using 6.6, so I'll upgrade to 6.6.1 and retest. Preusmably you're only interested if this behaviour persists in 6.6.1. I'll check both cases and make a test cases for them if necessary. Thanks, Alistair ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Optimising UTF8-CString -> String marshaling, plus comments on withCStringLen/peekCStringLen
> {- Arity: 4 Strictness: LSSL -}
Right. Unboxed args are always given the annotation L. So that function
is strict in that pointer arg, but GHC is choosing not to unbox it. I'm
not sure why that's the case.
I thought maybe it was because I hadn't said -funbox-strict-fields,
but it didn't change when I did.
> Is there some semantic advantage to bang-patterns, or is it just a
> syntactic convenience?
It's syntactic convenience.
I've noticed differences between strictness guards and bang-patterns
with GHC. This is a problem, I think, because bang-patterns are GHC
only, and I wanted to keep the code portable. This strictness guard:
readUTF8Char :: Int -> Int -> Ptr Word8 -> IO Char
readUTF8Char x offset p
| () !x !offset !p !False = undefined
| otherwise =
...
where
x ! y = seq x y
results in this simplifier output:
[Arity 3
Str: DmdType LSS]
$wreadUTF8Char_r38I =
\ (ww_s30B :: GHC.Prim.Int#)
(w_s30D :: GHC.Base.Int)
(w1_s30E :: GHC.Ptr.Ptr GHC.Word.Word8) ->
However, if I change this to:
{-# OPTIONS_GHC -fbang-patterns #-}
...
readUTF8Char :: Int -> Int -> Ptr Word8 -> IO Char
readUTF8Char !x !offset !p
| otherwise =
then I get this simpifier output:
[Arity 3
Str: DmdType LLL]
$wreadUTF8Char_r38n =
\ (ww_s2Zk :: GHC.Prim.Int#)
(ww1_s2Zo :: GHC.Prim.Int#)
(ww2_s2Zs :: GHC.Prim.Addr#) ->
Also, with bang-patterns I've noticed that fromUTF8Ptr transforms
into two functions, which contain very similar code:
[Arity 5]
Foreign.C.UTF8.$s$wfromUTF8Ptr =
\ (acc_X151 :: GHC.Base.String)
(new_s_a2GQ :: GHC.Prim.State# GHC.Prim.RealWorld)
(a87_a2GR :: GHC.Base.Char)
(ww_s2ZH :: GHC.Prim.Addr#)
(sc_s36j :: GHC.Prim.Int#) ->
[Arity 4
Str: DmdType LLSL]
Foreign.C.UTF8.$wfromUTF8Ptr =
\ (ww_s2ZD :: GHC.Prim.Int#)
(ww1_s2ZH :: GHC.Prim.Addr#)
(w_s2ZJ :: GHC.Base.String)
(w1_s2ZK :: GHC.Prim.State# GHC.Prim.RealWorld) ->
$wfromUTF8Ptr calls itself and $s$wfromUTF8Ptr, but $s$wfromUTF8Ptr
only every calls itself, so $wfromUTF8Ptr could be considered the
wrapper, and $s$wfromUTF8Ptr the worker, I guess.
AFAICT it's a transformation of the various cases in fromUTF8Ptr:
| x <= 0x7F -> fromUTF8Ptr (bytes-1) p (chr x:acc)
| x <= 0xBF && bytes == 0 -> error "fromUTF8Ptr: ..."
| x <= 0xBF -> fromUTF8Ptr (bytes-1) p acc
| otherwise -> do
c <- readUTF8Char x bytes p
fromUTF8Ptr (bytes-1) p (c:acc)
The first case, x <= 0x7F, results in a call to $s$wfromUTF8Ptr.
The third case, x <= 0xBF, results in a call to $wfromUTF8Ptr.
The last case, otherwise, results in a call to $s$wfromUTF8Ptr.
The calls to $s$wfromUTF8Ptr pass the newly constructed Char and the
rest of the String separately, and they are cons'ed in $s$wfromUTF8Ptr.
Not sure what benefit this gives...
I don't know what transformation causes this, but it was a bit of a surprise.
Alistair
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[Haskell-cafe] How to read -ddump-hi output (and other phases) from GHC
I'm collecting links to documents describing some of GHC's optimisation output flags, like -ddump-hi and -ddump-simpl. I'll add stuff to this wiki page: http://www.haskell.org/haskellwiki/Performance/GHC So far I've found little bits in the GHC manual, like: 4.16.3. How to read Core syntax http://www.haskell.org/ghc/docs/latest/html/users_guide/options-debugging.html#id3130643 (and the Encoding module has the actual rules for the Unique names) http://darcs.haskell.org/ghc/compiler/utils/Encoding.hs 6.2. Faster: producing a program that runs quicker http://www.haskell.org/ghc/docs/latest/html/users_guide/faster.html (see "How do I find out a function's strictness?") Any other hints? Alistair ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Fwd: [Haskell-cafe] Optimising UTF8-CString -> String marshaling, plus comments on withCStringLen/peekCStringLen
(this time include the list, too)
-- Forwarded message --
From: Alistair Bayley <[EMAIL PROTECTED]>
Date: 04-Jun-2007 16:13
Subject: Re: [Haskell-cafe] Optimising UTF8-CString -> String
marshaling, plus comments on withCStringLen/peekCStringLen
To: Duncan Coutts <[EMAIL PROTECTED]>
On 04/06/07, Duncan Coutts <[EMAIL PROTECTED]> wrote:
Are you sure fromUTF8Ptr is strict in its ptr arg? Try with a ! pattern
on that arg. You'll need -fbang-patterns.
Is there some semantic advantage to bang-patterns, or is it just a
syntactic convenience? 'cause once the guard is in there, it's not
much bother to maintain.
You can also get ghc to tell you what strictness it inferred for your
functions. It's shown in the .hi file. Use ghc --show-iface UTF8.hi.
I tried -ddump-hi and got:
$wfromUTF8Ptr :: base:GHC.Prim.Int#
-> base:GHC.Ptr.Ptr base:GHC.Word.Word8
-> base:GHC.Base.String
-> base:GHC.Prim.State# base:GHC.Prim.RealWorld
-> (# base:GHC.Prim.State# base:GHC.Prim.RealWorld,
base:GHC.Base.String #)
{- Arity: 4 Strictness: LSSL -}
Assuming the LSSL tokens are in the same order as the function
arguments, the first argument is lazy - GHC.Prim.Int#. hmmm some
cognitive dissonance here.
I'm a bit puzzled as to why it's in the .hi file at all - it's not an
exported function.
(I also see quite a bit of code in the hi-dump. Presumably this
permits cross-module inlining, for those selected functions?)
Alistair
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Re: [Haskell-cafe] Optimising UTF8-CString -> String marshaling, plus comments on withCStringLen/peekCStringLen
On 04/06/07, Duncan Coutts <[EMAIL PROTECTED]> wrote:
On Mon, 2007-06-04 at 09:43 +0100, Alistair Bayley wrote:
> After some experiments with the simplifier, ...
> The "portable" unboxed version is within about 15% of the unboxed version
> in terms of time and allocation.
Well done.
Of course, that might be saying more about the performance of the
unboxed version...
Yeah. In Data.ByteString.Char8 we invent this w2c & c2w functions to
avoid the test. There should probably be a standard version of this
unchecked conversion.
Bulat suggested unsafeChr from GHC.Exts, but I can't see this. I guess
I could roll my own; after all it's just (C# (chr# x)).
> BTW, what's the difference between the indexXxxxOffAddr# and
> readXxxxOffAddr# functions in GHC.Prim?
Right. So it'd only be safe to use the index ones on immutable arrays
because there's no way to enforce sequencing with respect to array
writes when using the index version.
In this case I'm reading from a CString buffer, which is (hopefully)
not changing during the function invocation, and never written to by
my code. So presumably it'd be pretty safe to use the index-
functions.
> - Ptrs don't get unboxed. Why is this? Some IO monad thing?
Got any more detail?
OK. readUTF8Char's transformation starts with this:
$wreadUTF8Char_r3de =
\ (ww_s33v :: GHC.Prim.Int#) (w_s33x :: GHC.Ptr.Ptr GHC.Word.Word8) ->
If we expect it to unbox, I'd expect the Ptr to become Addr#. Later,
this (w_s33x) gets unboxed just before it's used:
case w_s33x of wild6_a2JM { GHC.Ptr.Ptr a_a2JO ->
case GHC.Prim.readWord8OffAddr# @ GHC.Prim.RealWorld a_a2JO 1 s_a2Jf
readUTF8Char is called by fromUTF8Ptr, where there's a little Ptr
arithmetic. The Ptr argument to fromUTF8Ptr is unboxed, offset is
added, and the result is reboxed so that it can be consumed by
readUTF8Char. All a bit unnecessary, I think e.g.
Foreign.C.UTF8.$wfromUTF8Ptr =
...
let {
p'_s38N [Just D(T)] :: GHC.Ptr.Ptr GHC.Word.Word8
[Str: DmdType]
p'_s38N =
__scc {fromUTF8Ptr main:Foreign.C.UTF8 !}
case w_s33J of wild11_a2DW { GHC.Ptr.Ptr addr_a2DY ->
GHC.Ptr.Ptr @ GHC.Word.Word8 (GHC.Prim.plusAddr# addr_a2DY ww_s33H)
}
} in
...
I'd prefer the Ptr arg to fromUTF8Ptr to also be unboxed, so that the
primitive plusAddr# can be used directly on it before it's passed to
readUTF8Char. Perhaps instead I could push this Ptr arithmetic down to
readUTF8Char, and pass it the constant Ptr to the start of the buffer,
and the offset into it, rather than a Ptr to the current position.
Alistair
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[Haskell-cafe] Optimising UTF8-CString -> String marshaling, plus comments on withCStringLen/peekCStringLen
Hello cafe,
D'ya fancy an optimisation exercise?
In Takusen we currently marshal UTF8-encoded CStrings by first turning the
CString into [word8], and then running this through a [Word8] -> String
UTF8 decoder. We thought it would be more space-efficient (and hopefully
faster) to marshal directly from the CString buffer, rather than use
an intermediate list. We assumed it would be most space-efficient by
working backwards from the end of the CString buffer, like the
peekArray/peekArray0 functions in Foreign.Marshal.Array.
So I implemented it and benchmarked against the original UTF8 marshaling
function, which simply converts CString -> [Word] -> String.
And to my surprise, the [Word8] -> String solution seems to be faster,
and uses less memory, than the function which creates the String directly
from the CString buffer.
Now I appreciate that GHC's optimisations are quite effective (presumably
deforestation should take credit here), but I thought I'd ask the
haskell-cafe optimiser if we could do better with the direct-from-buffer
function. I'm loath to start eyeballing GHC Core, but if needs must...
The code is attached.
I also have some comments/questions about the various CStringLen functions
in Foreign.C.String. The Haddock comment for CStringLen states:
"A string with explicit length information in bytes..."
and for CWString something similar:
"A wide character string with explicit length information in bytes..."
I know this is a blatant lie, though, because the code (unless I've grossly
misunderstood it) for newCStringLen, withStringLen, newCWStringLen, and
withCWStringLen all return the number of Haskell Chars in the String
i.e. the number of Unicode chars, NOT the number of bytes.
However, for the sake of inconsistency, the peekC{W}StringLen functions
take, respectively, the number of Word8 or Word16/Word32 elements (whether
CWString is Word16 or Word32 depends on your plaform, apparently) in the
C{W}String array/buffer. So the outputs from newCStringLen etc are not
reliably usable as inputs to their duals (peekCStringLen etc.) The only
cases that they do work in this way is where the CStrings are encoded with
fixed-width encodings i.e. there are no surrogate units in the encoding.
So we have three different approaches:
1. Haddock comments say bytes
2. with/newC{W}StringLen returns unicode char count
3. peekC{W}StringLen expects Word8 or Word16 count
(1) and (3) can be considered equivalent, in the sense that if you know the
number of Word16 units then you know the number of Word8 units, and vice versa.
It'd be nice if we could have one consistent aproach. For a start, I think
we should eliminate (2), because it's dead easy the get the number of
unicode chars from a String (length, if you didn't know). So whether to
settle on (1) or (3) depends on what the most likely use case is for the
length information. Presumably it's going to be passed to a foreign
function which expects the length either in bytes or in Word16/Word32
units. Does anyone have any evidence or opinion as to which case is the
most common: bytes, or encoding units?
Alistair
-- |
-- Module : Foreign.C.UTF8
-- Copyright : (c) 2004 John Meacham, Alistair Bayley
-- License : BSD-style
-- Maintainer : [EMAIL PROTECTED]
-- Stability : experimental
-- Portability : portable
--
-- Marshall Haskell Strings to and from UTF8-encoded CStrings.
-- This module's code is inspired by John Meacham's UTF8 en- & de-coders,
-- and also those found in the HXT library (module Text.XML.HXT.DOM.Unicode).
--
-- Note that the -Len functions all return the length in bytes,
-- not Chars (this is more useful, as you are most likely to want
-- to pass the length to an FFI function, which is most likely
-- expecting the length in bytes). If you want the length in Chars,
-- well, you have the original String, so...
module Foreign.C.UTF8
( peekUTF8String, peekUTF8StringLen
, peekUTF8StringB, peekUTF8StringLenB
, newUTF8String, withUTF8String, withUTF8StringLen
, toUTF8String, fromUTF8String
, lengthUTF8, fromUTF8, toUTF8
) where
import Control.Monad (when)
import Data.Bits
import Data.Char
import Data.Word (Word8)
import Foreign.C.Types
import Foreign.C.String
import Foreign.Ptr
import Foreign.Marshal.Array
import Foreign.Storable
nullCChar :: CChar
nullCChar = 0
nullByte :: Word8
nullByte = 0
-- | Analogous to peekCString. Converts UTF8 CString to String.
peekUTF8String :: CString -> IO String
peekUTF8String cs = peekArray0 nullByte (castPtr cs) >>= return . fromUTF8
peekUTF8StringB :: CString -> IO String
peekUTF8StringB cs = fromUTF8Ptr0 (castPtr cs)
-- | Analogous to peekCStringLen. Converts UTF8 CString to String.
-- The resulting String will end either when @len@ bytes
-- have been converted, or when a NULL is found.
peekUTF8StringLen :: CStringLen -> IO String
peekUTF8StringLen (cs, len) = peekArra
Re: [Haskell-cafe] flip fix and iterate (was: Lazy IO and closing of file handles)
On 20/03/07, Bryan Burgers <[EMAIL PROTECTED]> wrote: On the topic of 'fix', is there any good tutorial for fix? I quite liked this one: http://dreamsongs.org/Files/WhyOfY.pdf Alistair ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: HS-Plugins 1.0 chokes on simple test, WinXP GHC-6.6
You managed to build the darcs version under ghc 6.6?
For me runghc setup.hs configure fails
with lots of strange error messages... (below)
other packages build ok.
Rene.
C:\repos\hs-plugins>darcs pull
plink: unknown option "-O"
Pulling from "http://www.cse.unsw.edu.au/~dons/code/hs-plugins";...
No remote changes to pull in!
C:\repos\hs-plugins>runghc Setup.lhs configure
I used an MSYS shell on Windows. It doesn't build with ghc/cabal on a
basic windows box - you need some sort of Unix clone. Looks like
you're using cygwin, I think ('cause you still have paths starting
with C:\).
Alistair
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[Haskell-cafe] Re: HS-Plugins 1.0 chokes on simple test, WinXP GHC-6.6
Is this using the darcs repository version of hs-plugins? That's the only versions that works with 6.6 Just got, built, and installed the repo version, and it has the same problem. Alistair ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] HS-Plugins 1.0 chokes on simple test, WinXP GHC-6.6
Does anyone have hs-plugins working on WinXP with ghc-6.6? When I run the simple test below I get this error: Main: c:/ghc/ghc-6.6/HSbase.o: unknown symbol `_free' Main: user error (Dynamic loader returned: user error (resolvedObjs failed.)) Am I doing something obviously dumb? Alistair module Test1 where test1 = putStrLn "test1" module Main where import Prelude hiding (catch) import Control.Exception import Data.List import System.Environment import System.Plugins instance Show (LoadStatus a) where show (LoadFailure errors) = "LoadFailure - " ++ (concat (intersperse "\n" errors)) show (LoadSuccess m p) = "LoadSuccess" main = do a <- getArgs let modName = case a of (n:_) -> n _ -> "Test1" let modPath = "./" ++ modName ++ ".o" let method = "test1" fc <- catch (load modPath [""] [] method) (\e -> return (LoadFailure ["Dynamic loader returned: " ++ show e])) case fc of LoadFailure errors -> do fail (concat (intersperse "\n" errors)) LoadSuccess modul proc -> do let p :: IO (); p = proc proc ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: Debugging concurrent program - no threads apparently running, but RTS still doing something.
> The problem is that when the main thread ends, the RTS doesn't stop > for another 6 or so seconds. The only thread that runs this long is > the handler (waitFor (secs 8.0)) but it has already been killed. So > I'm scratching my head a bit. Short answer: use -threaded. The runtime is waiting for a worker thread to complete before it can exit; even though your Haskell thread has been killed, there is still an OS thread executing Sleep() which was started by threadDelay, and this OS thread has to complete before the RTS can exit. We should really terminate the thread more eagerly, but since this only affects the non-threaded RTS fixing it isn't a high priority. Sweet, thanks. A note in the docs somewhere about this implementation detail would be nice; something that says you may want to consider -threaded because the implementation of threadDelay uses an OS thread. I suppose the best place would be in the docs for Control.Concurrent.threadDelay, although perhaps too a mention in section 4.10.7 of the ghc user's guide, because in there it says: "Note that you do not need -threaded in order to use concurrency; ..." It could say "Note that you do not need -threaded in order to use concurrency (unless you use threadDelay - see Control.Concurrent for details); ..." Alistair ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Debugging concurrent program - no threads apparently running, but RTS still doing something.
Below is a test case for a threading problem I can't figure out. It
models a socket server (here I've replaced the socket with an MVar, to
keep it simple). The idea is to have a listener which accepts incoming
requests on the socket. When one arrives, it forks a handler thread to
deal with the request, and returns to listening on the socket.
The handler thread is run in parallel with a timeout thread. In the
test case below, the handler takes too long, so the timeout thread
completes and kills the handler.
The problem is that when the main thread ends, the RTS doesn't stop
for another 6 or so seconds. The only thread that runs this long is
the handler (waitFor (secs 8.0)) but it has already been killed. So
I'm scratching my head a bit.
Also, any pointers to better techniques for designing and debugging
concurrent code are appreciated (is there a better way than putStrLn?)
Platform: ghc-6.6, Windows XP.
Thanks,
Alistair
-
module Main where
import Prelude hiding (catch)
import Control.Concurrent
import Control.Exception
import System.IO
secs :: Float -> Int
secs n = round (n * 100)
-- e.g. waitFor (secs 25)
waitFor n =
debug ("waitFor start " ++ show ((fromIntegral n) / 100.0))
>> threadDelay n
>> debug ("waitFor end " ++ show ((fromIntegral n) / 100.0))
debug msg = myThreadId >>= ( \t -> putStrLn $ (show t) ++ ": " ++ msg )
-- Thread 1 - start server then send message
main = do
hSetBuffering stdout LineBuffering
blockingInput <- newEmptyMVar -- like a socket; accept on a socket blocks
listnr <- forkIO (listener blockingInput)
putMVar blockingInput "hello"
waitFor (secs 2.0)
debug "main: done"
-- Thread 2 - listener.
-- Blocks on input; when input arrives, starts handler thread.
listener blockingInput = do
msg <- takeMVar blockingInput
serveRequest msg
-- in a real server we'd loop:
--listener blockingInput
debug "listener: done"
-- Start threads 3 and 4 - handler and timeout.
serveRequest msg = do
let acquire = return ()
let release _ = debug "handler release action"
forkIO (runTimeout 0.1 acquire release (handler msg))
return ()
handler msg _ = do
debug ("handler start: " ++ msg)
catch
(waitFor (secs 8.0) >> debug "handler end")
(\e -> debug ("Exception: " ++ (show e)) >> throwIO e)
runTimeout timeout acquire release action = do
handlerTid <- myThreadId
-- Use this to ensure the timeout thread doesn't start before the handler
-- i.e. give the handler a chance to start.
startTimeout <- newEmptyMVar
timeoutTid <- forkIO (runTimeoutThread startTimeout timeout handlerTid)
bracket acquire
( \a -> release a >> killThread timeoutTid )
( \a -> do
debug "runTimeout: start handler action"
putMVar startTimeout True
action a
debug "runTimeout: end handler action"
)
runTimeoutThread startTimeout timeout handlerTid = do
takeMVar startTimeout
debug "runTimeoutThread: start"
waitFor (secs timeout)
killThread handlerTid
debug "runTimeoutThread: end"
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Re: [Haskell-cafe] FFI basics
I would like to use FFI for the first time. Can someone give me a really, really simple complete example? Everything I found on the wiki seems way beyond that - maybe I missed it. I am using GHC. I am not using Windows. From the old wiki: http://www.haskell.org/hawiki/FfiCookbook http://www.haskell.org/hawiki/FfiExample http://www.haskell.org/hawiki/FfiTutorial http://www.haskell.org/hawiki/FfiWithArrays From the new wiki, this search shows you pages with titles starting with F: http://www.haskell.org/haskellwiki/?title=Special%3AAllpages&from=f&namespace=0 Is this the stuff you're referring to which seems to be "way beyond a simple example"? The FFI tutorial on the old wiki seems to be quite simple. If you find the pages on the old wiki useful, then please move them over to the new wiki. Or feel free to write some new pages that fill the gaps you find. There's quite a bit of Haskell code about which does FFI. From memory: darcs, and the various database libs (HSQL, HDBC, Takusen). Alistair ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] ANN: Takusen 0.6
We are pleased to announce a new release of Takusen. There are a large number of changes and bug-fixes: - Oracle support for processing cursors returned from procedure calls - withContinuedSession supports connection reuse (e.g. for persistent connections and connection pooling) - new README file with useful information about getting started with Takusen - new UTF8 en/de-coder (the old one was buggy) - PostgreSQL support for CalendarTime - improved Cabal Setup.hs script, which does a better job of modifying the installation to reflect installed DBMS's. This gives good ghci support (PostgreSQL users on Windows have a small extra step) - prepared statement API requires that users distinguish between queries and DML Our long-term plans are the same as ever: - large objects - ODBC and MS Sql Server backends Release: http://darcs.haskell.org/takusen/takusen-0.6.tar.gz Source: darcs get --partial http://darcs.haskell.org/takusen Oleg and Alistair ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Simple HTTP lib for Windows?
I'd like to write a very simple Haskell script that when given a URL, looks
up the page, and returns a string of HTML. I don't see an HTTP library in
the standard libs, and the one in Hackage requires Windows machines have GHC
and MinGW to be installed and in the PATH.
Is there a simple way to get the contents of a webpage using Haskell on a
Windows box?
This isn't exactly what you want, but it gets you partway there. Not
sure if LineBuffering or NoBuffering is the best option. Line
buffering should be fine for just text output, but if you request a
binary object (like an image) then you have to read exactly the number
of bytes specified, and no more.
Alistair
module Main where
import System.IO
import Network
main = client "www.haskell.org" 80 "/haskellwiki/Haskell"
client server port page = do
h <- connectTo server (PortNumber port)
hSetBuffering h NoBuffering
putStrLn "send request"
hPutStrLn h ("GET " ++ page ++ "\r")
hPutStrLn h "\r"
hPutStrLn h "\r"
putStrLn "wait for response"
readResponse h
putStrLn ""
readResponse h = do
closed <- hIsClosed h
eof <- hIsEOF h
if closed || eof
then return ()
else do
c <- hGetChar h
putChar c
readResponse h
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Re: [Haskell-cafe] importing Distribution.Compat.FilePath fails
On 18/11/06, Magnus Therning <[EMAIL PROTECTED]> wrote: Could not find module `Distribution.Compat.FilePath': it is hidden (in package Cabal-1.1.6) I want to use 'joinFileName'. Try upgrading to 1.1.6.1. This explains why: http://www.haskell.org/pipermail/libraries/2006-October/005996.html Alistair ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Writing binary files
On 21/08/06, Udo Stenzel <[EMAIL PROTECTED]> wrote: Neil Mitchell wrote: > I'm trying to write out a binary file, in particular I want the > following functions: > > hPutInt :: Handle -> Int -> IO () > > hGetInt :: Handle -> IO Int > > For the purposes of these functions, Int = 32 bits, and its got to > roundtrip - Put then Get must be the same. > > How would I do this? I see Ptr, Storable and other things, but nothing > which seems directly useable for me. hPutInt h = hPutStr h . map chr . map (0xff .&.) . take 4 . iterate (`shiftR` 8) hGetInt h = replicateM 4 (hGetChar h) >>= return . foldr (\i d -> i `shiftL` 8 .|. ord d) 0 This of course assumes that a Char is read/written as a single low-order byte without any conversion. But you'd have to assume a lot more if you started messing with pointers. (Strange, somehow I get the feeling, the above is way too easy to be the answer you wanted.) Udo. What's wrong with the following i.e. what assumptions is it making (w.r.t. pointers) that I've missed? Is endian-ness an issue here? Alistair hPutInt :: Handle -> Int32 -> IO () hGetInt :: Handle -> IO Int32 int32 :: Int32 int32 = 0 hPutInt h i = do alloca $ \p -> do poke p i hPutBuf h p (sizeOf i) hGetInt h = do alloca $ \p -> do bytes <- hGetBuf h p (sizeOf int32) when (bytes < sizeOf int32) (error "too few bytes read") peek p ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] ANN: Takusen 0.5
Oleg and I are pleased to announce the release of a new version of Takusen (it's been a while; so long that we don't remember the last version number we used). The most significant code change is a new internal design (courtesy of Oleg) which gives better separation of concerns like statement preparation, binding, and result-set processing. Also of note is a conversion to darcs, and hosting at haskell.org (thanks to Simon Marlow): darcs get http://darcs.haskell.org/takusen ... which also has the nice property that the Haddock documentation is browseable online: http://darcs.haskell.org/takusen/doc/html/index.html A comprehensive description of API usage can be found in the documentation for module Database.Enumerator: http://darcs.haskell.org/takusen/doc/html/Database-Enumerator.html We hope that the use of darcs will encourage contributions... Other changes: - support for multiple result sets returned from functions (PostgreSQL only). Oracle support for this is in the pipeline, which will allow use of nested cursors, and processing RefCursors returned as output parameters from procedure calls. Future plans: - Cabalisation - use of Data.Time instead of System.Time - ODBC and MS Sql Server backends For those of you unfamiliar with Takusen, here is our HCAR blurb: Takusen is a library for accessing DBMS's. It is a low-level library like HSQL, in the sense that it is used to issue SQL statements. Takusen's "unique-selling-point" is a design for processing query results using a left-fold enumerator. For queries the user creates an iteratee function, which is fed rows one-at-a-time from the result-set. We also support processing query results using a cursor interface, if you require finer-grained control. Currently we fully support Oracle, Sqlite, and PostgreSQL. Alistair ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Building Data.Time on WinXP GHC6.4.1
Has anyone built Ashley's Data.Time package on Windows? I ask because timestuff.c fails to compile for me because it refers to fields (tm_zone, tm_gmtoff) in struct tm which don't seem to exist on Windows (at least, mingw). Alistair ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Haskell poker server
> I wrote a poker server in Erlang (link in signature) and I'm learning > Haskell with an eye towards using it with Erlang. Erlang would take > care of the overall control, etc. whereas Haskell would take care of > the rest. I'm stuck with the basics I'm afraid and Haskell hackers > don't seem to be active this weekend ;). There's a public holiday on Monday in the UK; I don't know about other European states... I should have mentioned darcs: http://darcs.net/ A distributed revision control system is bound to contain some good networking examples. > I'm trying to write the poker server in Haskell to compare against my > other implementations, specifically the Erlang one. The server talks > a binary protocol. A packet notifying the player that a game has > started looks like this: > > 01 5 7 > ++-+-+ > | 24 | GID | Seq | > ++-+-+ > > I'm wondering, though, if someone would be kind enough to show how a > packet like above could be sent and retrieved using Haskell sockets. > I think this would serve as an excellent example to be posted at the > Haskell Wiki. I also think that Haskell has a lot of interesting > features that could well simplify my poker coding. I just need a > little help to get started. Below is a contrived, non-optimal first attempt. The server just reads seven bytes from the socket, prints them, and quits. And the client just sends seven bytes and quits. This is not good example code from just about any POV (for example: the client sending a byte-at-a-time, no interrupt masks, no exception handling), but it does show that you can send and receive bytes. The possibly dismaying thing is that you need code from networking, IO, and FFI libraries, so there are quite a few API's to digest. --- module Server where import Network import System.IO import Foreign.Marshal.Alloc import Foreign.Storable import Foreign.Ptr import Data.Word import Control.Monad (when) main = withSocketsDo run run = do sock <- listenOn (PortNumber 8080) (handle, _, _) <- accept sock getSevenBytes handle hClose handle sClose sock getSevenBytes handle = do allocaBytes 7 $ \buffer -> do readCount <- hGetBuf handle buffer 7 printBytes buffer (readCount-1) printBytes buffer count = printByte buffer count 0 printByte buffer count n = do b <- peekByteOff buffer n -- tell compiler what type of data is in buffer: Word8 let byte :: Word8; byte = b putStrLn $ "Byte " ++ (show n) ++ ": " ++ (show byte) when (count > n) (printByte buffer count (n+1)) -- module Client where import Network import System.IO import Foreign.Storable import Foreign.Marshal.Alloc import Data.Word main = withSocketsDo $ do handle <- connectTo "localhost" (PortNumber 8080) putByte handle 24 putByte handle 1 putByte handle 2 putByte handle 3 putByte handle 4 putByte handle 5 putByte handle 6 hClose handle putByte :: Handle -> Word8 -> IO () putByte handle byte = do allocaBytes 1 $ \buffer -> do poke buffer byte hPutBuf handle buffer 1 ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] How to use STArray?
> There are also STArray examples on the wiki at > http://haskell.org/hawiki/ImperativeHaskell > > This includes a very high performance use of STUArray example (from > Autrijus), and a ST.Lazy example that I wrote that uses STArray. Thanks. I saw these, but couldn't quite figure out what I needed to do for my program. I might add a note about helping the type-checker with the array type overloading. BTW, the STArray version of my code is honkin' fast (well, compared to the immutable array versions). And memory usage is way down, too. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] How to use STArray?
> > makeArray :: Int -> Int -> a -> ST s (STArray s Int a) > > makeArray lower upper val = newArray (-lower, upper) val > ^ > Is negation of lower intentional here? Yes, 'tis. Arguable as to whether or not it's a good idea, as it changes the inerface. In my program I use two types of array: - indexed from 1 to n - indexed from a -ve lower to a +ve upper So in this case it made sense to just pass the lower bound and negate it in the wrapper. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] about Ghci
Works in the "current" directory too, which is what I do under WinXP. I have a run_ghci.bat file in my src folder, which looks something like: set path=c:\ghc\ghc6.4\bin;%path% start ghci and the .ghci file is in this dir too. Christian Maeder wrote: SCOTT J. wrote: Hi, I use Windows XP and I like to start Ghci in extended mode. What do I have to do in order not having to type always :set -fglasgow-exts under unix this line can be put in a file ".ghci" in your home directory. Maybe $HOME is a variable under windows as well (and it is looked up accordingly). Christian http://www.haskell.org/ghc/docs/latest/html/users_guide/ghci-dot-files.html ___ 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 to convert from "IO String" to String
Try > l = [ 0, 255, 255, 255, 255, 0, 255, 255, 255, 255 > , 0, 255, 255, 255, 255, 0] > testConvertToList01 = TestCase $ do > img <- readImage "../data-test/diagonalImage.pgm" > assertEqual "" l (convertToList img) A TestCase is just an IO action (take a look at the HUnit source code). Alistair. Dmitri Pissarenko wrote: Hello! Thanks for your answer! You probably want something like... l = [0, 255, 255, 255, 255, 0, 255, 255, 255, 255, 0, 255, 255, 255, 255, 0] testConvertToList01 = do img <- readImage "../data-test/diagonalImage.pgm" return $ TestCase $ assertEqual "" l (convertToList img) When I use this test case definition, I'm getting an error when constructing the test suite: tests = TestList [testCommentLine01, testCommentLine02, testConvertToList01] GHCi writes TestLik.hs:22: Couldn't match `Test' against `IO Test' Expected type: Test Inferred type: IO Test In the list element: testConvertToList01 In the first argument of `TestList', namely `[testCommentLine01, testCommentLine02, testConvertToList01]' Best regards Dmitri Pissarenko -- Dmitri Pissarenko Software Engineer http://dapissarenko.com ___ 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] Building GUIs for Haskell programs
You will find this page useful for finding libraries: http://www.haskell.org/libraries/ As for GUI stuff, I believe wxHaskell is the most actively maintained toolkit, and probably your best bet. Alistair. Hello! I want to learn to create GUIs with Haskell. Which GUI frameworks can you recommend? Thanks Dmitri Pissarenko ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
