September 2008 - Haskell-Cafe

HStringTemplate to generate html tables
by Thomas Hartman 18 Sep '08

18 Sep '08

I am trying to use HStringTemplate for generating html tables, for use in http://happstutorial.com:5001 The best I could do is below. Seems awfully kludgy. Can someone suggest a better way, which keeps me inside the StringTemplate way of doing things? (Eg, no suggestions to use HTML.* libraries, which are nice for some things but are a higher barrier to entry than just jumping in and writing html.) Some kind of map structure... for each... ? Thanks for any help! thomas. {-# LANGUAGE NoMonomorphismRestriction #-} import Text.StringTemplate import Control.Applicative import qualified Text.PrettyPrint as PP main = putStrLn . PP.render . toPPDoc $ tableFromCells cells cells = [["mee","mah","moh"],["fee","fah","foh"]] -- This does generate an html table, but seems horribly obfuscated. -- is there machinery for doing things like html table generation -- in some better way than this hack where </end><start> -- tags are used as a separator? -- I would imagine something like -- newSTMP "$cells:{<td>$it$</td>}:{<tr>$it</tr>}:{<table>$it</table>}" -- which works a bit like a list comprehension tableFromCells cells = setAttribute "cells" cells . optInsertTmpl [("separator","</td><td>")] $ newSTMP "$cells:\ \{<tr><td>$it$</td></tr>}:\ \{<table>$it$</table>}$"

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Real World HAppS: Cabalized, Self-Demoing HAppS Tutorial (Version 3)
by Thomas Hartman 18 Sep '08

18 Sep '08

I pushed a new version of happs-tutorial to the online demo at http://happstutorial.com:5001 This is also on hackage: cabal install happs-tutorial. (now version 3.) or darcs get http://code.haskell.org/happs-tutorial for the latest The demo/tutorial has the same basic functionality as the last release -- just a login form essentially -- but a lot more bling now. Like menu link items that change colors when the page is clicked. Also the login form that gives sane error messages. The focus for this release was on explaining how I used StringTemplate with HAppS. Hopefully in version 4 I'll finally get to State and Macid! And hopefully some functionality that actually does something beyond just showing what users have created logins :) Thomas

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Re: [Haskell-cafe] Re: Float instance of 'read'
by Richard A. O'Keefe 18 Sep '08

18 Sep '08

On 18 Sep 2008, at 3:20 am, Mauricio wrote: > Agree about the answer, not about the question. The > correct one would be "is it possible to change haskell > syntax to support the international notation (not any > locally sensitive one) for decimal real numbers? Would > a change in 'read' be a good first step?" For some sense of "possible", the answer is clearly yes. However, it is perhaps misleading to call commas "THE international notation". The plain fact of the matter is that whatever any standards body may say, there are MANY notations for numbers. You might as well ask "is it possible to change Haskell syntax to support only the *real* Arabic digits ... for ... numbers". The Arabic script is used in many countries, so it's international. I don't read Arabic letters at all, but to me numbers written in Arabic script are no weirder than numbers using commas instead of dots. I would draw readers' attention to http://engineers.ihs.com/news/2006/nist-decimal-international.htm which says that (1) China, India, and Japan use decimal points, not commas. (2) There was a resolution of the CGPM in 2003 "endorsing the use of the point on the line as a decimal sign". (3) In June 2006, ISO agreed to allow the use of dots as decimal points in international standards. As it happens, the decimal point character I greatly prefer is the traditional British raised dot, but I can live with a low dot. I am 100% behind internationalised input and output, but allowing commas in numbers inside programming languages that already use commas for other purposes is, let's be polite, not a terribly good idea. You could probably get away with it in Lisp, but how many numbers are there in (1,2,3)? One thing that definitely is missing from Haskell numbers, and which I greatly miss, is a "thousands separator". Ada got around the dot/comma/apostrophe/whatever issue for thousands separators by using the underscore. For an unsigned decimal integer, this means allowing [0-9](_?[0-9])* instead of [0-9]+. It works really well, despite not being ANYBODY's cultural convention. > > > I know this looks difficult, but I'm sure it deserves at > least some thinking. We have previous examples for > less important issues: ghc does accept Windows end > of line conventions, the minus and sign needs special > syntax, and '.' can be used as decimal separator even > if it's use as function notation. > > Best, > Maurício > > _______________________________________________ > Haskell-Cafe mailing list > Haskell-Cafe(a)haskell.org > http://www.haskell.org/mailman/listinfo/haskell-cafe > > > > ==================================================================== > Auto Generated Mail > Footer If this email is requesting your > password then it is a HOAX. > DO NOT reply to the email. > Validate this footer at the > Otago University web site keyword search: information security phish > ==================================================================== > > > -- If stupidity were a crime, who'd 'scape hanging?

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Strongly Typed Memory Areas
by John Van Enk 18 Sep '08

18 Sep '08

Was Iavor/Mark's paper ever implemented as a GHC extension? "Strongly Typed Memory Areas" http://galois.com/down/2006_ID_Strongly.pdf -- /jve

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Exceptions
by Adrian Neumann 18 Sep '08

18 Sep '08

Hello, I think it'd be nice if the compiler could warn me if there are any exceptions which I'm not catching, similar to checked exceptions in Java. Does anyone know of a possibility to do that in Haskell? Adrian

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ANN: pandoc 1.0.0.1
by John MacFarlane 18 Sep '08

18 Sep '08

I'm pleased to announce the release of pandoc version 1.0.0.1. Pandoc aspires to be the swiss army knife of text markup formats: it can read markdown and (with some limitations) HTML, LaTeX, and reStructuredText, and it can write markdown, reStructuredText, HTML, DocBook XML, OpenDocument XML, ODT, RTF, groff man, MediaWiki markup, GNU Texinfo, LaTeX, ConTeXt, and S5. Pandoc's markdown syntax includes extensions for LaTeX math, tables, definition lists, footnotes, and more. HackageDB: http://hackage.haskell.org/cgi-bin/hackage-scripts/package/pandoc User's guide: http://johnmacfarlane.net/pandoc/README.html Examples: http://johnmacfarlane.net/pandoc/examples.html Interactive demo: http://johnmacfarlane.net/pandoc/trypandoc/ Haddock docs: http://johnmacfarlane.net/pandoc/doc/pandoc/ Repository: http://pandoc.googlecode.com/ Bug tracker: http://code.google.com/p/pandoc/issues/list Mailing list: http://groups.google.com/group/pandoc-discuss Some highlights of this release: + New GNU Texinfo writer (contributed by Peter Wang) + New OpenDocument XML writer (contributed by Andrea Rossato) + New ODT (OpenOffice document) writer + New MediaWiki markup writer + New delimited code block syntax + Handy generic functions for querying and transforming documents without lots of boilerplate (thanks to Andrea Rossato) + Cleaner build system: pandoc can now be built as a regular Cabal package + New dependencies: utf8-string and zip-archive + Code is -Wall clean + New Windows installer + Better support for math, including display math + Better HTML sanitizing for use in web applications + Many minor improvements and bug fixes (see changelog for details) Pandoc can optionally be compiled with support for + syntax highlighting of delimited code blocks, using the highlighting-kate library (over 50 languages are supported) (specify -fhighlighting) + automatically generated citations and bibliography, using Andrea Rossato's hs-citeproc library (specify -fciteproc) I am particularly excited about Rossato's experimental citation support. It's basically a BibTeX-like system that one can use in any of pandoc's output formats. So you can have automatically generated citations in a blog post, a wiki page, or even a man page! It's not yet complete, but it's far enough along for those with an adventurous spirit to use. I am very grateful to everyone who contributed bug reports and code, and especially to Andrea Rossato and Peter Wang for their major contributions.

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announcing darcs 2.0.3pre1
by Eric Kow 18 Sep '08

18 Sep '08

Hi everybody, I am very pleased to announce the first pre-release of darcs 2.0.3, available at http://www.darcs.net/darcs-2.0.3pre1.tar.gz This pre-release includes a few major bug fixes and a handful of interesting features. I expect darcs 2.0.3 to be more reliable than its predecessors. We have better HTTP support, safer handling of the pending patch and a more solid implementation of common flags (for example, darcs get --to-match or darcs diff --patch). For more details, see the attached list. So what are we working on to get darcs 2.0.3 out the door? Aside from the usual testing, I hope that we can round out our improved reliability with a few small user interface enhancements, mostly to help users avoid some common pitfalls of real world version control: - issue53: detection of Windows reserved device names - issue971: hashed darcs check - issue1003: more tolerant darcs-transfer mode - issue1039: detection of seemingly unrelated repositories (see http://bugs.darcs.net for details) In the meantime, please give darcs 2.0.3pre1 a try and let us know how things go! Thanks, -- Eric Kow <http://www.nltg.brighton.ac.uk/home/Eric.Kow> PGP Key ID: 08AC04F9

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Ajax-Haskell framework?
by Greg Meredith 18 Sep '08

18 Sep '08

Haskellians, Is there an Ajax-Haskell framework? In case there are many, is there a preferred one? Experiences people would like to share? Best wishes, --greg -- L.G. Meredith Managing Partner Biosimilarity LLC 806 55th St NE Seattle, WA 98105 +1 206.650.3740 http://biosimilarity.blogspot.com

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Haskell Weekly News: Issue 85 - September 13, 2008
by Brent Yorgey 18 Sep '08

18 Sep '08

--------------------------------------------------------------------------- Haskell Weekly News http://sequence.complete.org/hwn/20080913 Issue 85 - September 13, 2008 --------------------------------------------------------------------------- Welcome to issue 85 of HWN, a newsletter covering developments in the [1]Haskell community. Announcements citeproc-hs. Andrea Rossato [2]announced the first release of [3]citeproc-hs, a Haskell implementation of the [4]Citation Style Language. citeproc-hs adds a Bibtex-like citation and bibliographic formatting and generation facility to [5]Pandoc. Twidge. John Goerzen [6]announced the release of [7]Twidge, a command-line Twitter and Identi.ca client. Real World HAppS: Cabalized, Self-Demoing HAppS Tutorial (Version 3). Thomas Hartman [8]announced a new version of [9]happs-tutorial, with a correspondingly updated [10]online demo. generic list functions fixed. Jim Apple reported that genericTake, genericDrop, and genericSplitAt have [11]been fixed so they are now total functions (they used to fail on negative integer inputs, unlike their ungeneric counterparts). The Monad.Reader (13) - Call for copy. Wouter Swierstra [12]announced a call for copy for Issue 13 of the [13]Monad.Reader. The deadline for submitting articles is February 13, 2009. Heads Up: code.haskell.org is upgrading to darcs 2. Duncan Coutts [14]announced that /usr/bin/darcs on code.haskell.org will soon be upgraded to version 2. Most users should be unaffected as darcs 2 works just fine with repositories in darcs 1 format, and has been extensively tested for correctness. Discussion packages and QuickCheck. Conal Elliott [15]asked what methods of organization people use to package up QuickCheck tests for their libraries. Hackage needs a theme song!. Jason Dagit wrote a [16]theme song for Hackage! Jobs Gamr7. Lionel Barret De Nazaris [17]announced that [18]Gamr7, a startup in France focused on procedural city generation for the game and simulation market, is looking for a senior developer/technical director. senior role at Credit Suisse. Ganesh Sittampalam [19]announced that [20]Credit Suisse is seeking to recruit an expert in functional programming for a senior role in the Global Modelling and Analytics Group (GMAG) in the Securities Division. Blog noise [21]Haskell news from the [22]blogosphere. * Douglas M. Auclair (geophf): [23]What is declarative programming?. * John Goerzen (CosmicRay): [24]New Twitter Client: Twidge. * Mark Jason Dominus: [25]Return return. Mark's mind is blown by the code "return return" appearing in a paper by Mark Jones. * Eric Kow (kowey): [26]darcs weekly news #3. * Ketil Malde: [27]The FastQ file format for sequences. * >>> Nathan Sanders: [28]Real World Haskell. Nathan experiments with porting some of his Python code to Haskell. * Andrea Vezzosi (Saizan): [29]Results from GSoC. Andrea's GSoC work on a high-level dependency framework for Cabal is going to be released in a separate package for now, [30]hbuild. * >>> Ricky Clarkson: [31]An IRC Bot in Haskell, 20% code, 80% GRR. Ricky shares his experiences, frustrations, and eventual success writing a simple IRC bot in Haskell. * >>> Yaakov Nemoy: [32]Xmonad 0.8 released. * Luke Palmer: [33]The problem with Coq. ...is, according to Luke, that it doesn't have a nice graphical interface. * >>> James Cowie: [34]Haskell! yes no?. James dives into learning some Haskell. Verdict so far: a "very nice language". Quotes of the Week * EvilTerran: this is hard to express in this type system. i'm going to make my own type system instead! About the Haskell Weekly News New editions are posted to [35]the Haskell mailing list as well as to [36]the Haskell Sequence and [37]Planet Haskell. [38]RSS is also available, and headlines appear on [39]haskell.org. To help create new editions of this newsletter, please see the information on [40]how to contribute. Send stories to byorgey at cis dot upenn dot edu. The darcs repository is available at darcs get [41]http://code.haskell.org/~byorgey/code/hwn/ . References 1. http://haskell.org/ 2. http://article.gmane.org/gmane.comp.lang.haskell.cafe/44471 3. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/citeproc%2Dhs 4. http://xbiblio.sourceforge.net/csl/ 5. http://johnmacfarlane.net/pandoc/ 6. http://article.gmane.org/gmane.comp.lang.haskell.cafe/44453 7. http://software.complete.org/twidge 8. http://article.gmane.org/gmane.comp.lang.haskell.cafe/44410 9. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/happs-tutorial 10. http://happstutorial.com:5001/ 11. http://hackage.haskell.org/trac/ghc/ticket/2533 12. http://article.gmane.org/gmane.comp.lang.haskell.general/16420 13. http://www.haskell.org/haskellwiki/The_Monad.Reader 14. http://article.gmane.org/gmane.comp.lang.haskell.general/16419 15. http://thread.gmane.org/gmane.comp.lang.haskell.cafe/44259 16. http://thread.gmane.org/gmane.comp.lang.haskell.cafe/44450 17. http://article.gmane.org/gmane.comp.lang.haskell.cafe/44211 18. http://www.gamr7.com/ 19. http://article.gmane.org/gmane.comp.lang.haskell.general/16422 20. http://www.credit-suisse.com/ 21. http://planet.haskell.org/ 22. http://haskell.org/haskellwiki/Blog_articles 23. http://logicaltypes.blogspot.com/2008/09/what-is-declarative-programming.ht… 24. http://changelog.complete.org/posts/752-New-Twitter-Client-Twidge.html 25. http://blog.plover.com/prog/springschool95.html 26. http://koweycode.blogspot.com/2008/09/darcs-weekly-news-3.html 27. http://blog.malde.org/index.php/2008/09/09/the-fastq-file-format-for-sequen… 28. http://sandersn.com/blog/index.php?title=real_world_haskell 29. http://vezzosi.blogspot.com/2008/09/even-if-this-blog-has-been-silent-since… 30. http://hackage.haskell.org/trac/hackage/wiki/HBuild 31. http://rickyclarkson.blogspot.com/2008/09/irc-bot-in-haskell-20-code-80-grr… 32. http://loupgaroublond.blogspot.com/2008/09/xmonad-08-released.html 33. http://luqui.org/blog/archives/2008/09/07/the-problem-with-coq/ 34. http://www.jcowie.co.uk/2008/09/haskell-yes-no/ 35. http://www.haskell.org/mailman/listinfo/haskell 36. http://sequence.complete.org/ 37. http://planet.haskell.org/ 38. http://sequence.complete.org/node/feed 39. http://haskell.org/ 40. http://haskell.org/haskellwiki/HWN 41. http://code.haskell.org/~byorgey/code/hwn/

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a question about Database.HDBC.ODBC
by Changying Li 18 Sep '08

18 Sep '08

I want to use hdbc to connect my mysql test db. so I set up my /etc/odbcinst.ini : [MySQL] Description = ODBC Driver for MySQL Driver = /usr/lib/libmyodbc.so Setup = /usr/lib/libodbcmyS.so FileUsage = 1 and /etc/odbc.ini: [test] Description = MySQL database test Driver = MySQL Server = localhost Database = test Port = 3306 User = root Socket = /tmp/mysql.sock Option = Stmt = user chylli@localhost must use password to connect mysql. other users needn't. I connect db like this: Prelude Database.HDBC.ODBC Database.HDBC> handleSqlError (connectODBC "DSN=test") *** Exception: user error (SQL error: SqlError {seState = "[\"HY000\"]", seNativeError = -1, seErrorMsg = "connectODBC/sqlDriverConnect: [\"1045: [unixODBC][MySQL][ODBC 3.51 Driver]Access denied for user 'chylli'@'localhost' (using password: NO)\"]"}) Prelude Database.HDBC.ODBC Database.HDBC> handleSqlError (connectODBC "DSN=test;UID=chylli") Prelude Database.HDBC.ODBC Database.HDBC> in another term: mysql> show processlist; +----+-------------+-----------+------+---------+------+-------+------------------+ | Id | User | Host | db | Command | Time | State | Info | +----+-------------+-----------+------+---------+------+-------+------------------+ | 31 | chylli¶è | localhost | test | Sleep | 1483 | | NULL | | 43 | root | localhost | test | Sleep | 116 | | NULL | my question is: 1. why not HDBC.ODBC use configuration in /etc/odbc.ini ? if is use, then connectODBC "DSN=test" should use root as user without password and it should succeed. 2. when using UID=chylli, why the user in 'show processlist' is not chylli but 'chylli¶è' ? if it use account 'chylli', that connection should fail. but in fact it succeed !!! -- Thanks & Regards Changying Li

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