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ANNOUNCE: X Haskell Bindings
by Antoine Latter 09 Jan '09

09 Jan '09

Folks, I'd like to announce a preview-release of the X Haskell Bindings. The goal of the library is to provide low-level access to the X11 protocol, in the spirit of the X C Bindings This is a "preview" because I expect that the interface will still need to change - but I do plan on bump the minor-version number when that happens. On Hackage: http://hackage.haskell.org/cgi-bin/hackage-scripts/package/xhb What works: All X protocol requests have corresponding functions. I haven't tested all of them. Requests are sent asynchronously - the caller is not blocked until they need to examine the result of the request Errors and Events are unpacked into Haskell data types It should be safe to use the same connection in multiple threads What needs improvement: * There's no documentation - you pretty much need to be sitting down with the X Protocol reference while using this library. Once we can get documentation into the XML that this library is generated from, we should be able to generate Haddock documentation at the same time * A lot of parameters are specified using integer types, even though a proper Haskell enum-like data type exists. * Many functions take a ValueParam argument, which is not fun to work with in a language like Haskell. I have plans for how to make these more type-safe, but this is something else that requires more information in the XML protocol descriptions. * There's no way to share a connection between XHB and libraries built against the Xlib bindings. * I haven't done any benchmarking, so it's possible that all of this is pretty slow. Keep in mind that this is a library for the X Protocol - it alone is not a replacement for XLib - XLib does a lot more than pushing and pulling on a file-handle. Related releases: Spencer Janssen has released FFI bindings to Xauth: http://hackage.haskell.org/cgi-bin/hackage-scripts/package/Xauth-0.1 I've released a small library for determining the byte-ordering of the system: http://hackage.haskell.org/cgi-bin/hackage-scripts/package/byteorder-1.0.0 Related projects: X C Bindings: http://xcb.freedesktop.org/ -Antoine

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ANNOUNCE: Data.TCache 0.5.5
by Alberto G. Corona 09 Jan '09

09 Jan '09

The main addition of this versión is the capablity to safely handle transact, and serialize to permanent storage many datatypes simultaneously in the same piece of code and incrementally. Just register each new datatype (with registerType :: <Type>). So it is not necessary to glue all types in advance in a single algebraic datatype. I suppose taht "enhanced composablility" applies to this feature. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/TCache In this release: Added a Data.TCache.Dynamic. (SEE dynamicsample.hs) - Can handle, transact, and serialize to disk many datatypes simultaneously and incrementally - Dynamic uses the same interface than TCache and add *DResource(s) calls for handling many datatypes simultaneously - Safe dynamic data handling trough a lighter, indexable and serializable version of Data.Dynamic - Added KEY object for retrieving any object of any type. Data.Tcache is a transactional cache with configurable persistence. It tries to simulate Hibernate for Java or Rails for Ruby. The main difference is that transactions are done in memory trough STM. There are transactional cache implementations for some J2EE servers like JBOSS. TCache uses STM. It can atomically apply a function to a list of cached objects. The resulting objects go back to the cache (withResources). It also can retrieve these objects (getResources). Persistence can be syncronous (syncCache) or asyncronous, wtih configurable time between cache writes and configurable cache clearance strategy. the size of the cache can be configured too . All of this can be done trough clearSyncCacheProc. Even the TVar variables can be accessed directly (getTVar) to acceess all the semantic of atomic blocks while maintaining the persistence of the TVar updates. Persistence can be defined for each object: Each object must have a defined key, a default filename path (if applicable). Persistence is pre-defined in files, but the readResource writeResource and delResource methods can be redefined to persist in databases or whatever. There are Samples in the package that explain the main features.

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Re: [Haskell-cafe] Re: Hypothetical Haskell job in New York
by John Goerzen 09 Jan '09

09 Jan '09

On Fri, Jan 09, 2009 at 01:06:44PM +0100, Manlio Perillo wrote: > John Goerzen ha scritto: >> On Thu, Jan 08, 2009 at 09:46:36PM +0100, Manlio Perillo wrote: >>> I'm speaking about servers, not clients. >>> >>> How much of pure Haskell internet servers are used in a production >>> environment, in the "open internet" (and not in restricted LANs)? >> >> Does that really matter? I tend to judge technology based on its >> merits for my work, not on who uses it. > > Well, testing a server is not easy. > You can have a server that works for you without problems, but in > different environment it gives problems. I completely understand that, as a sysadmin that has to maintain mission-critical systems. Unfortunately, it's also so often used as a justification for using "whatever everyone else has". So many people buy Exchange for that reason, as an example. Exchange has a pretty long history of bugs that make it really unsuitable for use in the Enterprise, yet people use it anyway because they think everyone uses it. A particularly amusing example is at http://software.complete.org/software/issues/show/114 - my little OfflineIMAP program appears to be able to take down entire Exchange databases and force a restore from backup, because Exchange has a hard-coded limit of 32k different mail header names *per installation*, and OfflineIMAP generates one unique header each time it uploads a message to the server. If my program can do that accidentally, imagine what someone with a will to do that could do. Nobody would have ever tried Haskell, Python, or Perl in mission-critical situations if they always thought like that. Somebody has to be first, and I see no problem with it being us, as long as we are confident of the outcome. Part of the calculus has to be: 1) Can we test it under stress? 2) How confident are we that it will behave right under conditions we can't test? (Esp. malicious ones) 3) Can we fix it ourselves if it breaks? How many others can fix it? I really like Haskell because of #2. While there is no 100% guarantee, I feel better about Haskell not throwing a type error in some obscure condition than I do about Python not doing so. I also like #2 because of the availability of both HUnit and QuickCheck. Write your code right, and you can QuickCheck a significant part of it. -- John

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10 PhD, PostDoc, and Engineering Positions offered!!
by CFP 09 Jan '09

09 Jan '09

10 PhD, PostDoc, and Engineering Positions offered!! ----------------------------------------------------------------------- | HATS: Highly Adaptable and Trustworthy Software using Formal Models | ----------------------------------------------------------------------- HATS is a new Integrated Project funded by the European Union, within the programme "Future and Emerging Technologies" (FET) of the 7th Framework Programme (subject to contract) starting March 2009. The project partners from Chalmers Technical University, Gothenborg, Sweden University of Oslo, Norway Royal Institute of Technology, Stockholm, Sweden Technical University of Madrid, Spain IMDEA Software, Spain Technical University of Kaiserslautern, Germany, University of Bologna, Italy, Centrum voor Wiskunde en Informatica (CWI), Amsterdam, Netherlands Norwegian Computer Center, Oslo, Norway Fredhopper B.V., Amsterdam, Netherlands Fraunhofer Institute for Experimental SE, Kaiserslautern, Germany, Katholieke Universiteit Leuven, Belgium are jointly advertising several 3-5 year PhD, PostDoc, and Engineering positions. The goal of HATS is a tool-supported framework and formal methodology for the development of long-lived and trustworthy software systems. Specifically, HATS will turn software product family (SWPF) development into a rigorous approach. The technical core of the project is an Abstract Behavioral Specification language which will allow precise description of SWPF features and components and their instances. For further information see: http://www.hats-project.eu Topic areas: Applicants should have a background and/or interest in one of the topics software modeling, modeling and programming languages, formal methods, verification, language-based security, type systems, or concurrency theory. The following positions are offered: * 2 PhD positions with emphasis on formal modeling and verification at Chalmers University of Technology. One of the positions is in the EU project CHARTER which is closely related to HATS. Application deadline is 9th February 2009. Contact: Prof. Reiner Haehnle. Further details and information on how to apply at http://www.chalmers.se/cse/EN/news/vacancies/positions/two-ph-d-student * A Research Software Engineer at Fredhopper (Amsterdam). The position will comprise of industrial research on modeling and verification of key components of Fredhopper's flagship product within the EU-funded HATS research project. Fredhopper is the Nr. 1 provider of Search & Merchandising solutions for online business in Europe and industrial leader in the HATS project. Apply by 31 January 2009 for the most optimal procedure. Contact for project information: Dr. Nikolay Diakov. More information and how to apply at: http://www.fredhopper.com/public/company-opps.php?cat=0&subcat=0#research-s… * 2 PostDoc positions at the University of Bologna. The emphasis is on formal modeling and verification of the kind of concurrent systems studied in Hats using various techniques, including behavioural techniques and type systems. Application deadline is 31 January (later applications may also be taken into account). Contact: Prof. Davide Sangiorgi, see: http://www.cs.unibo.it/~sangio/Hats/vacancies.txt * 3 PhD positions with emphasis on static analysis and security at the Technical University of Madrid/IMDEA Software. One of the positions is in the DOVES Spanish project, which is closely related to HATS. The application deadline is 25 January. Later applications may also be taken into account if the positions are not covered. Contact: Prof. German Puebla. Further details and information on how to apply at http://clip.dia.fi.upm.es/Job_Openings/hats-doves-phd-grants.html * 1 PhD and 1 PostDoc position in the area of software modeling and verification at the University of Kaiserslautern. The emphasis in the area of software modeling is on semantically founded integration of behavioral software models, feature-based descriptions of variability and programs. The emphasis in verification is on modular techniques for object-oriented models and model refinement. Application deadline is January 31. Later applications may also be taken into account. Contact: Prof. A. Poetzsch-Heffter. Further details and information on how to apply at http://softech.informatik.uni-kl.de/Homepage/OffeneStellen * Further positions will be announced at this space! Applicants should have (or expect to have at the start of employment): * For a PhD position: a good Masters level or excellent Bachelor level degree (or equivalent) in computer science, mathematics, or a closely related discipline with knowledge in the areas above. Please see also individual requirements at each site which can differ. * For a Postdoc position: a PhD in computer science or mathematics, preferably with research experience in one of the listed topic areas. * For a software engineer position: a Masters or PhD level level degree (or equivalent) in computer science, mathematics, or a closely related discipline with good knowledge in the areas of program verification, automata theory or discrete math. Knowledge of Java and some programming experience count as a plus. Regardless of the specific application instructions, each application should contain: 1) a full CV including letters of recommendation 2) a research statement, indicating the research directions you are interesting in and what relevant experience you have 3) transcripts of degree results where available. To apply, please follow the links given above. Expressions of interest received by 15 January 2009 are guaranteed full consideration. Specific application deadlines may vary. Early contact would be appreciated.

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ANNOUNCE: haskell-src-exts 0.4.8
by Niklas Broberg 09 Jan '09

09 Jan '09

Fellow Haskelleers, it is my pleasure to announce the new release of the haskell-src-exts package, version 0.4.8: http://hackage.haskell.org/cgi-bin/hackage-scripts/package/haskell-src-exts… darcs get http://code.haskell.org/HSP/haskell-src-exts This is a bug-fix release in the wake of the flurry of bug reports I received due to Neil Mitchell's release of hlint. Not all bugs have been squashed, but all the ones that I could handle with fairly small changes to the library should be. Those include deriving for MPTCs, importing constructor symbols, inline pragmas in instance declarations, scoped type variables, and a few more. There are some minor non-backwards compatible changes to the abstract syntax, but nothing too serious. The most pervasive is that the Match and PatBind constructors have an extra argument of type Maybe Type, representing an optional type signature. Derivings also are no longer just a list of class names, since those classes can now have extra parameters. Four things remain on the bug list: - Support for explicitly kinded arguments to type families. Shouldn't be too hard, but will require changes to the AST that I will leave for the next release. - Support for (un-parenthesised) higher-ranked types as arguments. haskell-src-exts supports e.g. foo :: b -> (forall a . [a]) -> b but not foo :: b -> forall a . [a] -> b. Supporting the latter is simply a parser issue, but a rather tricky one. - Correct handling of hyphened vars (an artifact of HSX/HSP) vs minus operators. This one is nasty. - Support for Unicode symbols for e.g. ->. Fixing that would require me to have a Unicode-compliant editor, which it appears I don't. And I couldn't have someone else submit a patch either, since then I couldn't open the file anymore in my editor. So unless someone can point out a good Unicode-aware editor for Windows, I'm afraid this is a feature that won't be implemented. If you find anything else that haskell-src-exts fails on, please report it. Cheers and Happy Haskelling, /Niklas

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Hypothetical Haskell job in New York
by Tony Hannan 09 Jan '09

09 Jan '09

Hello Haskellers, I'm trying to convince my boss to use Haskell. His main concern is finding people who know Haskell when hiring. He is comfortable with Java because he knows he can always find a Java developer. So if I advertised we were looking for Haskell programmers in New York City, how many would respond? Please reply to this email if you would respond. Email me privately if you like and I will post the results to haskell-cafe later. Thanks, Tony

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Re: [Haskell-cafe] Re: Hypothetical Haskell job in New York
by John Goerzen 08 Jan '09

08 Jan '09

On Thu, Jan 08, 2009 at 09:46:36PM +0100, Manlio Perillo wrote: > I'm speaking about servers, not clients. > > How much of pure Haskell internet servers are used in a production > environment, in the "open internet" (and not in restricted LANs)? Does that really matter? I tend to judge technology based on its merits for my work, not on who uses it. The fact that Google uses Python didn't impact my decision to start using it, and it also didn't impact my decision to start using Haskell. > How much traffic they handle? > How hard are to maintain/update/develope/? Those, of course, are pretty good questions. > Personally, I only know http://hpaste.org/, based on > Server: HAppS/0.8.4 Take a look at Hackage. There are quite a few other Haskell web frameworks as well: everything from the low-level FastCGI to higher-level HSP and WASH. > And about HAppS, I'm not an Haskell expert, but reading the source I see > that static files are server (in the HTTP server) using > Data.ByteString.Lazy's hGetContents > > Is this ok? In what respect? The fact that something uses ByteString.Lazy.hGetContents doesn't imply a problem to me. It's a useful function. It can be used properly, or not, just as while or read() in C can be. It's not evil incarnate like sprintf() or anything :-) -- John

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Re: [Haskell-cafe] Re: Hypothetical Haskell job in New York
by Don Stewart 08 Jan '09

08 Jan '09

manlio_perillo: > Tony Hannan ha scritto: > >Let me give you more information about this hypothetical job posting. > >Our company is a startup CDN > >(http://en.wikipedia.org/wiki/Content_Delivery_Network) about 3 years > >old and doing well. You would hythothetically be one of 7 programmer who > >write all the software involved in a CDN including http server, dns > >server, monitoring, load balancing, customer and operator user > >interface, etc. The pay depends on experience but is good. > > > > Isn't it better to use Erlang for the http and dns server ? > > I don't really like the syntax, but you have many things already > implemented. > Unfortunately Haskell is not yet ready for this task. > > http://eddie.sourceforge.net/what.html > http://yaws.hyber.org/ > Umm... http and dns? You're kidding right? Half of hackage.haskell.org is devoted to networking tasks. -- Don

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ICFP: Child care at conference
by Matthew Fluet (ICFP Publicity Chair) 07 Jan '09

07 Jan '09

Potential ICFP attendees: The ACM-SIGPLAN Executive Committee, which oversees and sponsors ICFP, is considering expanding its travel grants for event participants in need of child care assistance. (Such expansion would also apply to other major SIGPLAN-sponsored conferences, such as PLDI, POPL, OOPSLA.) The purpose of this message is to solicit feedback from potential attendees regarding the desirability for child care assistance and what forms of assistance be most appropriate. If child care assistance at ICFP (or other SIGPLAN events) is of interest to you, please contact me (at icfp.publicity(a)gmail.com -or- fluet(a)tti-c.org) with your comments. Some questions of particular interest: * What age groups of children are most appropriate to cover? * What types of costs might SIGPLAN cover to facilitate your participation in events? Sincerely, -Matthew Fluet (ICFP Publicity Chair)

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possible bug in pretty-1.0.1.0
by John MacFarlane 05 Jan '09

05 Jan '09

I noticed a difference in how "hang" works between pretty-1.0.0.0 and pretty-1.0.1.0. I think it's a bug. If this isn't the right place to report it, please let me know where I should. (Maintainer is listed as libraries(a)haskell.org, but that is a closed mailing list. Perhaps Cabal should include a report-bugs-at field?) John GHCi, version 6.8.3: http://www.haskell.org/ghc/ :? for help ... Prelude Text.PrettyPrint> putStrLn $ render $ hang (char '*') 4 (text "hi" $$ text "there") Loading package pretty-1.0.0.0 ... linking ... done. * hi there GHCi, version 6.10.1: http://www.haskell.org/ghc/ :? for help ... Prelude Text.PrettyPrint> putStrLn $ render $ hang (char '*') 4 (text "hi" $$ text "there") Loading package pretty-1.0.1.0 ... linking ... done. * hi there

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