- Haskell-Cafe - Haskell.org

Fwd: ANN: website for Haskell regex testing
by Andrew M 29 Dec '13

29 Dec '13

Haskellers: I run a website for testing regular expressions and just added support for Haskell and wanted to see if you find it useful/what you think/if you have any suggestions. The site is RegexPlanet, the Haskell testing page is at: http://www.regexplanet.com/advanced/haskell/index.html It uses Text.Regex.TDFA flavor. You can see the source code on github: https://github.com/fileformat/regexplanet-haskell Disclaimer: I'm not a Haskell expert (actually, not even a newbie) and had someone else do the actual coding. Again, any feedback is appreciated. Thanks! Enjoy! Andrew

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Segmentation fault/access violation when CPLUS_INCLUDE_PATH not set correctly
by Henk-Jan van Tuyl 29 Dec '13

29 Dec '13

L.S., When I compile an application against an experimental version of wxHaskell*, the application always ends with the message: Segmentation fault/access violation in generated code , unless I set the environment variable CPLUS_INCLUDE_PATH to C:\Program Files\Haskell Platform\2013.2.0.0\mingw\lib\gcc\mingw32\4.5.2\include\c++\ , which is the same value as used when compiling wxHaskell. If I copy the contents of C:\Programs\Haskell Platform\2013.2.0.0\ to some other location and let CPLUS_INCLUDE_PATH point to the new location of directory c++, the segmentation fault message reappears. Why is this and how can create an application that also works on another computer? Regards, Henk-Jan van Tuyl * wxHaskell is a binding to the wxWidgets GUI library, which is written in C++ -- Folding@home What if you could share your unused computer power to help find a cure? In just 5 minutes you can join the world's biggest networked computer and get us closer sooner. Watch the video. http://folding.stanford.edu/ http://Van.Tuyl.eu/ http://members.chello.nl/hjgtuyl/tourdemonad.html Haskell programming --

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Name for the following combinators?
by Hans Höglund 28 Dec '13

28 Dec '13

Dear all, Recently I have found myself using these two combinators a lot: http://lpaste.net/97643 They basically allow composition of any m satisfying (Monad m, Traversable m). I have been thinking about moving them to a separate package and giving them better names (in the original paper, they are simply called join and bind). Does anyone have a better suggestion for the name of the package, module and the two combinators? Should they be called joinDefault, or simply called join and bind to be imported with a qualifier? This might be a bicycle-shed question, but I tend to find stylistic questions important when it comes to improving clarity and readability. Best wishes, Hans

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[Fp-nl] Call for participation: Dutch Functional Programming Day 2014
by Doaitse Swierstra 28 Dec '13

28 Dec '13

Dear all, The next Netherlands Functional Programming day (NL-FP 2014) will take place on Friday, January 10, 2014 at the University of Amsterdam at Amsterdam Science Park. You are all cordially invited to participate and, of course, to give a presentation. The day will largely follow the pattern of the previous NL-FP days with a moderately timed start, a day of enjoyable talks in between lunch and coffee breaks and ending with a joint dinner in a nearby restaurant. All further details can be found on the NL-FP 2014 site(s): http://staff.science.uva.nl/~grelck/nl-fp-day-2014.html http://staff.science.uva.nl/~grelck/nl-fp-dag-2014.html Hope to see you all in Amsterdam in January! Best regards, Clemens Grelck -- ---------------------------------------------------------------------- Dr Clemens Grelck Science Park 904 University Lecturer 1098XH Amsterdam Netherlands University of Amsterdam Institute for Informatics T +31 (0) 20 525 8683 Computer Systems Architecture Group F +31 (0) 20 525 7490 Office C3.105 www.science.uva.nl/~grelck ---------------------------------------------------------------------- _______________________________________________ Fp-nl mailing list Fp-nl(a)lists.science.uu.nl http://lists.science.uu.nl/mailman/listinfo/fp-nl

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integrating Happy & Alex monads
by Richard Cobbe 27 Dec '13

27 Dec '13

I'm working on a program in which I'd like to use Alex and Happy to parse the input. I've written the scanner, and it uses Alex's "monadUserState" wrapper to track source location and various other things. Now, the problem is to integrate it with the parser. As far as I can tell from reading the Happy documentation, I need to use a monadic Parser in Happy as well, but the manuals don't relaly provide a lot of information about how to integrate the two. And I haven't really been able to find many examples of this either. Lots of folks cite "the Haskell parser", although I'm not sure which implementation that's referring to. I did check out the GHC source, and while it contains an Alex parser specification, it doesn't look like anything actually *uses* this, preferring instead a handwritten parser. Could anyone point me to a discussion of how to integrate these two tools, or examples of places where folks have done this before? Thanks much, Richard

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finding "good work" in CS
by Dennis Raddle 27 Dec '13

27 Dec '13

It's me again, guy aged 45 thinking about doing graduate work in CS. I read this ebook about a guy's CS PhD, "The PhD Grind": <http://www.pgbovine.net/PhD-memoir.htm> It was enlightening. I used to think that software in the C.S. academic world must be well-written, seeing as it was written by computer scientists. (I didn't like the poorly organized and simple-minded code involved in my last job at NASA.) Turns out that academic code can be very poor indeed, sometimes just a hacked prototype meant to demonstrate an idea to get it published. It may be the youngest PhD students who are assigned the job of cranking out such prototypes. So what do I want to do for my life's work, once I can overcome this illness and get back to work full-time? I hope I can work with beauty in some form. I find Haskell to be beautiful, for instance. I like ideas, but I also like the process of implementing ideas in a quality way. I may not be suited to the academic world because I need to spend at least some of my time as a craftsman of code, doing something well. Is there an area with CS academia that is more about elegance, less about hacking up prototypes? The study of languages? Second, what if I thought of PhD not as a way to enter academia, but as a way to qualify me for the more interesting and creative C.S. jobs out there? What kinds of C.S. jobs involve real creative control, an opportunity to do things in an elegant way? I know that's a very broad question, so maybe those reading could mention single examples or things they've run into. No need to cover everything. Thanks, Dennis

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forever function laziness
by Eduardo Sato 26 Dec '13

26 Dec '13

Hello, guys. Recently I came across the definition of the function 'forever' on hoogle. I am intrigued that it works. The recursive definition does make sense to me in a mathematical way, but I can't figure out how it works under the hood in terms of thunks. To tell you the truth, I don't know how laziness works in general in haskell. Can someone help me understand how it works in this example, and give some pointers to materials on the subject? The "tying the knot" article on the wiki is pretty mind bending too. -- | @'forever' act@ repeats the action infinitely. forever :: (Monad m) => m a -> m b {-# INLINE forever #-}forever a = let a' = a >> a' in a' -- Eduardo Sato

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Re: [Haskell-cafe] Haskell Singapore Meetup
by Corentin Roux 26 Dec '13

26 Dec '13

Hi Jesse, Just saw your email. I started the data science team at Zalora and was behind the adoption of Haskell. As a short background, I didn't know how to program 2 years ago, when I left a finance job for a small startup in Australia. I didn't know anything about business intelligence either, and started with excel sheets. But the work was very repetitive so I picked up programming to try and automate some of it. After I moved to the South East Asian version of the same company, Zalora, I had read up a lot more, including books like SICP, and all of Paul Graham's essays. I liked both his concept of the "blub" ladder of abstraction, and his idea of using a programming language as a "secret weapon". Lisp is nice, but the pure nature of Haskell and the work that was done on the compiler both convinced me that it was a better secret weapon to solve my issue of not having enough budget or time to set up a standard BI setup (I separately was not too happy with SaaS providers anyway, so decided that in-house was the only way we could afford what I wanted). I had picked up enough Haskell to hire the first person (Dat Le) on the basis of his answers to a bunch of exercises we used as a filter (we were also helped by Hisham Zarka, current CMO of another Rocket company, Namshi and former Googler in MV). Dat did an extraordinary amount of work acting as proof of concept, much of it in Haskell, so it worked out even better than expected and we picked up enough budget to build a proper team. We called it "Data Science" because that seems to be the current buzz word for hiring smart guys. Haskell is unique in that: - it has a well defined standard with enormous amounts of research going into it (both the language, and its libraries); - the purity simplifies scaling, which I already needed, as well as all the standard improvements from catching most bugs before compiling, shorter code, etc.; - it is relatively hard to write Haskell that compiles as a beginner, thus acting as a natural talent filter (that can be expanded upon: it also attracts the kind of people who enjoy programming for its own sake, just like Lisps). I would disagree that there are very few people that know the language. I did put up my first ad as Python, with a preference for people with "experience in FPLs, like Haskell, Clojure, Erlang or Scala". I had over 200 applications, of which less than 5% were people we'd consider working with (mostly "Greetings! I believe my extensive experience and considerable skills make me an ideal fit for your company."). Every ad thereafter has been in Haskell, and on average over half the applicants are good enough to be hired (which is a great situation to be in as an employer, although I feel bad for the Haskellers meeting so few opportunities). The community's quality is simply exceptional. I'll post more about its use, which is rapidly expanding beyond "data science", in a few weeks. If anybody is interested: http://www.haskellers.com/jobs/61 Best, Corentin Le samedi 21 décembre 2013 05:59:30 UTC, Jesse Armand a écrit : > > Hi Paul, > > A follow-up from the meetup. I was tired yesterday after work. So, didn't > have the energy to socialize. > > Just a few of my thoughts. First of all, it was a good start to promote > haskell in Singapore. > > I'm very new to Haskell. I did some ruby, python and node.js at a very > small scale before. Most of time I do Objective-C programming as a job. > > Just finished reading Higher Order Functions, and will start learning > about making my own typeclasses. This is based on > http://learnyouahaskell.com. So, I barely know anything about the > language. Though, I'm aware that its popularity is growing, and also the > existence of a haskell web framework such as Yesod. > > So, for this reason, I am curious about how Zalora decided to choose > Haskell as a programming language. Given that, there are very few people > who know the language. It will also be great to understand where is it > being used on the technology stack, and some examples of how Haskell is > really advantageous for a particular use case. > > Thanks > > On Wednesday, December 18, 2013 6:12:52 PM UTC+8, Paul Meng wrote: >> >> Hi all, >> >> I've already posted on the reddit but forgot to post it here. >> >> It's going to be Christmas, and a good way to celebrate it is to have a >> Haskell meetup. On this Friday, Dec 20. We are going to host it at Google >> Singapore office. >> http://www.meetup.com/HASKELL-SG/events/154702892/ >> There would be a short sharing and have some time to meet with other >> Haskell programmers (or FP programmer in general) after the talk. >> If you happen to be in Singapore, welcome to stop by! >> >> For people signed up before, notice that we are moving from Zalora to >> Google's office to have a bigger meeting room. >> And due to the access policy, please fill out your full name, e-mail and >> company in the following form. >> >> https://docs.google.com/forms/d/1pTQA3eK7Qsxbq_Tw8nPPX6MIUnQuGsm23rT5bfhtw-… >> >> Paul Meng >> >

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Re: [Haskell-cafe] Parse HTML that is contain javascript
by akira kawata 25 Dec '13

25 Dec '13

Many thanks for your cooperations. I have decided to use xmlhtml instead of making my own html parser. 2013/12/25 akira kawata <a.kawashiro(a)gmail.com> > Hi, I am Akira. > I want to parse HTML file that is contain javascript. > But I cant come up with how to deal with script tag. > Is there anyone help me? > > Details of probrem > HTML code I want to parse is like following > > <html> > <script> > //<![CDATA[ >  > //]]> > </script> > </html> > > Because '<' is used as normal character in the script region, > I can not use my HTML parser there. > >

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Building PanDoc for iOS target, but failed in Haskell Template requirement by 'aeson' package
by Joe 25 Dec '13

25 Dec '13

Hi, I've been trying to cross-compile PanDoc for iOS target for the last few days. I have been quite successfull from building stage-1 GHC for iOS target and many packages dependencies required by PanDoc until I see that 'aeson' package require Haskell Template which is not supported in cross compilation. As pointed in iOS CrossCompiling Wiki page, it seems that Template Haskell doesn't work yet and still in wish list. Is there any hack or workaround to be able to cross-compile 'aeson' package for iOS target? Can I compile 'aeson' without Haskell Template? Anybody know when Template Haskell in CrossCompiling for iOS will be added? Thanks a lot! Best regards, Joe

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Parse HTML that is contain javascript
by akira kawata 25 Dec '13

25 Dec '13

Hi, I am Akira. I want to parse HTML file that is contain javascript. But I cant come up with how to deal with script tag. Is there anyone help me? Details of probrem HTML code I want to parse is like following <html> <script> //<![CDATA[  //]]> </script> </html> Because '<' is used as normal character in the script region, I can not use my HTML parser there.

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Munich Haskell Holiday Meeting
by Heinrich Hördegen 24 Dec '13

24 Dec '13

Dear all, I want to announce a special holiday meeting of Munich's Haskell user group. It will take place on the 27th of December at 19h30 at Cafe Puck. Check out the details here: http://www.haskell-munich.de/news I wish everyone a nice holiday! Heinrich

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hslogger and metalog compatibility
by Michael Orlitzky 24 Dec '13

24 Dec '13

Is anyone else using metalog (syslog implementation) along with hslogger to log to syslog? If I run the following with syslog-ng, it works. With metalog, I get nothing. Just want to make sure it isn't me before I report it. Prelude> :set prompt "ghci> " ghci> :m +System.Log.Logger ghci> :m +System.Log.Handler.Syslog ghci> sl <- openlog rootLoggerName [] USER DEBUG ghci> updateGlobalLogger rootLoggerName (addHandler sl) ghci> errorM rootLoggerName "This won't show up with metalog."

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NL-FP Day 2014, January 10, Update
by Doaitse Swierstra 23 Dec '13

23 Dec '13

Dear all, A warm welcome to all who registered since the last update email. As of today, we expect 56 participants to the 22nd Netherlands Functional Programming Day in 2014. All news regarding the day itself including - a complete programme, - abstracts for most of the talks, - an updated list of participants, - dinner location (de ponteneur), - registration fee (25EUR) can be found at http://staff.science.uva.nl/~grelck/nl-fp-day-2014.html http://staff.science.uva.nl/~grelck/nl-fp-dag-2014.html Merry Christmas and best wishes for the new year, Clemens -- ---------------------------------------------------------------------- Dr Clemens Grelck Science Park 904 University Lecturer 1098XH Amsterdam Netherlands University of Amsterdam Institute for Informatics T +31 (0) 20 525 8683 Computer Systems Architecture Group F +31 (0) 20 525 7490 Office C3.105 www.science.uva.nl/~grelck ----------------------------------------------------------------------

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Access to Mac OS X needed
by Roman Cheplyaka 23 Dec '13

23 Dec '13

Hi, I am working on fswatch[1,2], a cross-platform file system notification library. [1]: http://hackage.haskell.org/package/fsnotify [2]: https://github.com/haskell-fswatch/hfsnotify Occasionally it needs to be tested on Mac OS X. Could someone give me an unprivileged ssh access to a Mac OS X host with an installed Haskell Platform for this purpose? Roman

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New Functional Programming Job Opportunities
by Functional Jobs 23 Dec '13

23 Dec '13

Here are some functional programming job opportunities that were posted recently: Chief Data Scientist at Lazada http://functionaljobs.com/jobs/8671-chief-data-scientist-at-lazada Cheers, Sean Murphy FunctionalJobs.com

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Abstracting configuration directories
by Michael Orlitzky 23 Dec '13

23 Dec '13

I'm writing a small utility whose only non-portable code involves the two paths, /etc/htsnrc $HOME/.htsnrc These have sort-of analogues under Windows; in .NET they are available through something like, Environment.SpecialFolder.CommonApplicationData Environment.SpecialFolder.ApplicationData I personally will only ever need to run on Linux, but as a matter of principle I'd like to abstract the paths. Is there a library that can do this already?

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Clearing up the status of GHCi on Raspberry Pi
by Dan Krol 22 Dec '13

22 Dec '13

Hello, There seems to be a bit of confusing information out there regarding what is possible with regard to Haskell and Raspberry Pi. Specifically, availability of GHCi (and as such, the ability to compile certain thing such as Vector) in various versions of ghc. Debian Weezy came with GHC 7.4.1. It doesn't come with GHCi. This fact was reflected in what I've read online. So far so good. Now, we come to GHC 7.4.2.: http://www.haskell.org/haskellwiki/Raspberry_Pi#GHC_Status This currently says the following: "Note: GHCi does not currently work on ARM below version 7.4.2. See this post on haskell-cafe for information on this djhuk has been able to compile and install GHC-7.4.2 via QEMU to the Raspberry Pi but there still seems to be some work to do." This seems to imply that GHC 7.4.2. will include GHCi on arm. It implies that, though there were at the time of writing some unspecified problems, if one could get 7.4.2. working on their Rasperry Pi, one would get GHCi. Futher, I extrapolated this to mean that any version later than 7.4.2. would surely also have GHCi. Under the "Found on mailing lists" of this link: http://www.haskell.org/haskellwiki/ARM I similarly found: "GHCi (7.4.2) is working on ARM (Cubieboard with Ubuntu)" granted it doesn't say anything about Raspberry Pi. Well, my experience has shown otherwise. I upgraded my Raspberry Pi to Debian Jesse (currently the testing release), which gives me ghc as high as 7.6.3. GHCi? "command not found". I asked about this in #haskell on freenode, and somebody pointed me here: https://ghc.haskell.org/trac/ghc/wiki/Platforms This seems to imply that ARM does not have GHCi (though version is not specified in these tables). In fact, according to this same person, GHC altogether will not officially be supported on ARM until version 7.8. I'm not sure how that is reflected here. It seems to be Tier 2. Some Tier 2 things have GHCi. I figure we should sort this out, I'd be happy to edit the wikis myself but I want to make sure I understand what's going on. I understand this probably comes down to some nuances that are not expressed here. For user friendliness of the language and ecosystem I think such things should be made clear. As somebody coming to this wanting to accomplish something, I want a clear answer on what is available to me. It's been a source of frustration for me. Could somebody clear all this up for me? And while I'm at it, I would be grateful if somebody could explain to me how it is possible (if at all) to have ghci on my Raspberry Pi, short of compiling it myself. I'm not against compiling ghc, but I am against compiling it on my Raspberry Pi. Qemu I will consider, though. Thanks a lot, Dan

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Re: [Haskell-cafe] Haskell and Big Data
by He-chien Tsai 22 Dec '13

22 Dec '13

What I meant is that split the data into several parts,send each splited data to different computers, train them seperately, finally send the results back and combine those results. I didn't mean to use Cloud Haskell. 2013/12/20 上午5:40 於 "jean-christophe mincke" < jeanchristophe.mincke(a)gmail.com> 寫道： > > He-Chien Tsai, > > > its training result is designed for composable > > Yes it is indeed composable (parallel function of that lib) but parallelizing it on a cluster changes all the type because running on a cluster implies IO. > Moreover using Cloud Haskell (for instance) implies that: > 1. training functions should be (serializable) clojures, which can only be defined as module level (not as local -let/where - bindings). > 2. train is a typeclass function and is not serializable. > > So the idea behind HLearn are interesting but I do not see how it could be run on a cluster... But, unfortunately, I am not an Haskell expert. > > What do you think? > > Regards > > J-C > > > > On Thu, Dec 19, 2013 at 6:15 PM, He-chien Tsai <depot051(a)gmail.com> wrote: >> >> have you took a look at hlearn and statistics packages? it's even easy to parallellize hlearn on cluster because it's training result is designed for composable, which means you can create two model , train them seperately and finally combine them. you can also use other database such as redis or cassandra,which has haskell binding, as backend. for parallellizing on clusters, hdph is also good. >> >> I personally prefer python for data science because it has much more mature packages and is more interactive and more effective (not kidding. you can create compiled C for core datas and algorithms by python-like cython and call it from python, and exploit gpus for accelerating by theano) than haskell and scala, spark also has a unfinish python binding. >> >> 2013/12/18 下午3:41 於 "jean-christophe mincke" < jeanchristophe.mincke(a)gmail.com> 寫道： >> >> >> > >> > Hello Cafe, >> > >> > Big Data is a bit trendy these days. >> > >> > Does anybody know about plans to develop an Haskell eco-system in that domain? >> > I.e tools such as Storm or Spark (possibly on top of Cloud Haskell) or, at least, bindings to tools which exist in other languages. >> > >> > Thank you >> > >> > Regards >> > >> > J-C >> > >> > _______________________________________________ >> > Haskell-Cafe mailing list >> > Haskell-Cafe(a)haskell.org >> > http://www.haskell.org/mailman/listinfo/haskell-cafe >> > > >

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Troubleshooting-type questions
by Lucas Paul 21 Dec '13

21 Dec '13

I wouldn't want to clutter the list with off-topic stuff, so I'll ask first. Once in a while I'll have trouble trying to use some piece of software, like Shpider or Yesod. Is it on-topic to ask specific "how-do-I-use/do"-type questions for particular packages like that on this list? -- Lucas Paul

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Haskell Job Opportunity
by Jeff Polakow 21 Dec '13

21 Dec '13

AlephCloud is an early stage Silicon Valley startup creating a secure cloud content management system. Haskell is our main server side language and we are looking to hire a few more Haskell programmers. Some topics of interest to us are: cloud services, cryptography/security, cross compilation (javascript, iOS, ARM). We are somewhat flexible about location, though we¹d prefer people on the west coast of the US. If interested feel free to contact me (jeff(a)alephcloud.com) for more information, or send a message (and/or a resume) to resume(a)alephcloud.com. thanks, Jeff

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Fwd: Package Maintenance: dtd-types, dtd-text
by Montez Fitzpatrick 20 Dec '13

20 Dec '13

I would like to take over maintenance of the following two packages: "dtd-types" & "dtd-text". I have attempted to e-mail the original package author with no response. I realize this can be a busy time of the year; personally, I would have no problems what-so-ever when/if the original author returns to relinquish stewardship of the aforementioned packages. Montez

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Haskell Weekly News: Issue 288
by Daniel Santa Cruz 20 Dec '13

20 Dec '13

Welcome to issue 288 of the HWN, an issue covering crowd-sourced bits of information about Haskell from around the web. This issue covers the week from December 08 to 14, 2013. Quotes of the Week * nlogax: With FRP.Sodium and Graphics.UI.GLUT you could put together a MonadSodium GLUTamate Top Reddit Stories * The reason why `cabal update` takes so long Domain: github.com, Score: 175, Comments: 89 On Reddit: [1] http://goo.gl/NCsf34 Original: [2] http://goo.gl/BLp5LB * structured-haskell-mode — Structured editing minor mode for Haskell in Emacs Domain: github.com, Score: 103, Comments: 37 On Reddit: [3] http://goo.gl/t8dyd9 Original: [4] http://goo.gl/v6W7js * Amazing LVars talk by Linsey Kuper Domain: youtu.be, Score: 86, Comments: 20 On Reddit: [5] http://goo.gl/JcbNQn Original: [6] http://goo.gl/JPyVnG * 24 Days of Hackage: acid-state Domain: ocharles.org.uk, Score: 84, Comments: 15 On Reddit: [7] http://goo.gl/CBU18T Original: [8] http://goo.gl/W4u7GG * 24 Days of Hackage: pandoc Domain: ocharles.org.uk, Score: 66, Comments: 14 On Reddit: [9] http://goo.gl/rUO2yc Original: [10] http://goo.gl/PhTTFC * text 1.0.0.0 Domain: hackage.haskell.org, Score: 64, Comments: 25 On Reddit: [11] http://goo.gl/9k7ksP Original: [12] http://goo.gl/ISESbc * 24 Days of Hackage: async Domain: ocharles.org.uk, Score: 59, Comments: 11 On Reddit: [13] http://goo.gl/rhrdgM Original: [14] http://goo.gl/C4sQeh * 24 Days of Hackage: sbv (guest post by Tikhon Jelvis) Domain: ocharles.org.uk, Score: 57, Comments: 21 On Reddit: [15] http://goo.gl/YkLqo9 Original: [16] http://goo.gl/frHdyn * 24 Days of Hackage: data-memocombinators Domain: ocharles.org.uk, Score: 56, Comments: 18 On Reddit: [17] http://goo.gl/0FgDo6 Original: [18] http://goo.gl/4GcFKd * Bryan O'Sullivan - Package dependency management: more debate is needed Domain: plus.google.com, Score: 51, Comments: 45 On Reddit: [19] http://goo.gl/Xr7NkU Original: [20] http://goo.gl/f1VPxt * 24 Days of Hackage: gloss Domain: ocharles.org.uk, Score: 49, Comments: 10 On Reddit: [21] http://goo.gl/yBAlXk Original: [22] http://goo.gl/mplvhP * The future of array-oriented computing in Haskell — a survey Domain: justtesting.org, Score: 45, Comments: 11 On Reddit: [23] http://goo.gl/doVpgz Original: [24] http://goo.gl/ezkftd * Progress Reporting in Shake Domain: neilmitchell.blogspot.it, Score: 42, Comments: 3 On Reddit: [25] http://goo.gl/1hvu6c Original: [26] http://goo.gl/4izrhK * [ANN] SFML and SFML-control Domain: self.haskell, Score: 40, Comments: 20 On Reddit: [27] http://goo.gl/NhMJbR Original: [28] http://goo.gl/NhMJbR * 24 Days of Hackage: heist Domain: ocharles.org.uk, Score: 40, Comments: 28 On Reddit: [29] http://goo.gl/FtvnLs Original: [30] http://goo.gl/nEU9Hw Top StackOverflow Questions * How are J/K/APL classified in terms of common paradigms? votes: 10, answers: 1 Read on SO: [31] http://goo.gl/ImISrG * Is it possible to extend free monad interpreters? votes: 9, answers: 5 Read on SO: [32] http://goo.gl/CiJupH * How to detect a Monad? votes: 8, answers: 4 Read on SO: [33] http://goo.gl/WiUhba * Why do Haskell type signature declarations have multiple arrows? votes: 7, answers: 3 Read on SO: [34] http://goo.gl/0LWfMb * “Inheriting” instance of wrapped type votes: 7, answers: 1 Read on SO: [35] http://goo.gl/qBhrqD * Equality function for pair components votes: 7, answers: 1 Read on SO: [36] http://goo.gl/mLk49N * Motivation of having Functional Dependencies votes: 7, answers: 1 Read on SO: [37] http://goo.gl/E31zjJ * Haskell - Lenses, use of 'to' function votes: 7, answers: 1 Read on SO: [38] http://goo.gl/5A028y * What does PINNED mean in -hc profile of Haskell program? votes: 6, answers: 1 Read on SO: [39] http://goo.gl/Qx9eJB Until next time, [40]+Daniel Santa Cruz References 1. https://github.com/nominolo/HTTP/commit/b9bd0a08fa09c6403f91422e3b23f08d339… 2. http://www.reddit.com/r/haskell/comments/1sh67u/the_reason_why_cabal_update… 3. https://github.com/chrisdone/structured-haskell-mode 4. http://www.reddit.com/r/haskell/comments/1sd3aj/structuredhaskellmode_struc… 5. http://youtu.be/8dFO5Ir0xqY 6. http://www.reddit.com/r/haskell/comments/1skf3x/amazing_lvars_talk_by_linse… 7. http://ocharles.org.uk/blog/posts/2013-12-14-24-days-of-hackage-acid-state.… 8. http://www.reddit.com/r/haskell/comments/1svlm2/24_days_of_hackage_acidstat… 9. http://ocharles.org.uk/blog/guest-posts/2013-12-12-24-days-of-hackage-pando… 10. http://www.reddit.com/r/haskell/comments/1srcz6/24_days_of_hackage_pandoc/ 11. http://hackage.haskell.org/package/text-1.0.0.0 12. http://www.reddit.com/r/haskell/comments/1st4jl/text_1000/ 13. http://ocharles.org.uk/blog/posts/2013-12-13-24-days-of-hackage-async.html 14. http://www.reddit.com/r/haskell/comments/1stf7l/24_days_of_hackage_async/ 15. http://ocharles.org.uk/blog/guest-posts/2013-12-09-24-days-of-hackage-sbv.h… 16. http://www.reddit.com/r/haskell/comments/1shnr7/24_days_of_hackage_sbv_gues… 17. http://ocharles.org.uk/blog/posts/2013-12-08-24-days-of-hackage-data-memoco… 18. http://www.reddit.com/r/haskell/comments/1settx/24_days_of_hackage_datamemo… 19. https://plus.google.com/103469090998089605155/posts/HdC6oCy8RWW 20. http://www.reddit.com/r/haskell/comments/1sdwot/bryan_osullivan_package_dep… 21. http://ocharles.org.uk/blog/posts/2013-12-10-24-days-of-hackage-gloss.html 22. http://www.reddit.com/r/haskell/comments/1sl0y5/24_days_of_hackage_gloss/ 23. http://justtesting.org/post/69439080517/the-future-of-array-oriented-comput… 24. http://www.reddit.com/r/haskell/comments/1sfg7l/the_future_of_arrayoriented… 25. http://neilmitchell.blogspot.it/2013/12/progress-reporting-in-shake.html 26. http://www.reddit.com/r/haskell/comments/1sqsyi/progress_reporting_in_shake/ 27. http://www.reddit.com/r/haskell/comments/1sjemq/ann_sfml_and_sfmlcontrol/ 28. http://www.reddit.com/r/haskell/comments/1sjemq/ann_sfml_and_sfmlcontrol/ 29. http://ocharles.org.uk/blog/posts/2013-12-11-24-days-of-hackage-heist.html 30. http://www.reddit.com/r/haskell/comments/1sob71/24_days_of_hackage_heist/ 31. http://stackoverflow.com/questions/20558170/how-are-j-k-apl-classified-in-t… 32. http://stackoverflow.com/questions/20564633/is-it-possible-to-extend-free-m… 33. http://stackoverflow.com/questions/20495627/how-to-detect-a-monad 34. http://stackoverflow.com/questions/20459981/why-do-haskell-type-signature-d… 35. http://stackoverflow.com/questions/20481718/inheriting-instance-of-wrapped-… 36. http://stackoverflow.com/questions/20515404/equality-function-for-pair-comp… 37. http://stackoverflow.com/questions/20526828/motivation-of-having-functional… 38. http://stackoverflow.com/questions/20528718/haskell-lenses-use-of-to-functi… 39. http://stackoverflow.com/questions/20478805/what-does-pinned-mean-in-hc-pro… 40. https://plus.google.com/105107667630152149014/about

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Job opportunities at Galois Inc.
by Iavor Diatchki 19 Dec '13

19 Dec '13

Hello, Galois is still hiring! We are located in beautiful Portland, Oregon and are currently looking for researchers, principal investigators, and software engineers, including those with expertise in functional programming, formal methods, computer security, control systems, informatics, or networking. For more information, take a look at http://corp.galois.com/careers and please feel free to drop me an e-mail if you have questions. Happy Holidays, -Iavor

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Haskell and Big Data
by jean-christophe mincke 19 Dec '13

19 Dec '13

Hello Cafe, Big Data is a bit trendy these days. Does anybody know about plans to develop an Haskell eco-system in that domain? I.e tools such as Storm or Spark (possibly on top of Cloud Haskell) or, at least, bindings to tools which exist in other languages. Thank you Regards J-C

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Persisting a Map
by Andrew Cowie 19 Dec '13

19 Dec '13

I have a Map. It's a lovely Map, with keys and values and everything. It's not _that_ large. Few 10s of MB at most. Unfortunately, I need to persist it somewhat reliably. I'd somewhat like to avoid having to use an external database (obviously a key/value store like Riak would work, but that's a major dependency to impose on the system) so I'm wondering if there is a low tech way to do this. I can control concurrent access to the file (or whatever), and the file system is robust. So that part is fine. I just need to externalize the map. I'm wondering if just using cereal or so would be sufficient (there is a Serialize instance, of course), or whether I should be using some acid-state thing, or a Haskell binding to gdbm, or sqlite, or... Any suggestions? AfC Sydney

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ANNOUNCE: Ajhc Haskell Compiler 0.8.0.10 Release
by Kiwamu Okabe 18 Dec '13

18 Dec '13

We are happy to announce Ajhc 0.8.0.10 as Christmas release! You can get Ajhc using "cabal install drift && cabal install ajhc" command. The usage is found at Ajhc's project web site http://ajhc.metasepi.org/. The source code at https://github.com/ajhc/ajhc. Welcome sending any bugs or your ideas to https://github.com/ajhc/ajhc/issues. ## News ### Android demo Android demo application using Haskell is available at Google Play. https://play.google.com/store/apps/details?id=org.metasepi.ajhc.android.cube ### Clear license notification * Runtime: [MIT License](https://github.com/ajhc/ajhc/blob/master/rts/LICENSE) * Haskell libraries: [MIT License](https://github.com/ajhc/ajhc/blob/master/lib/LICENSE) * The others: [GPLv2 or Later](https://github.com/ajhc/ajhc/blob/arafura/COPYING) ## Other changes * Depend on DrIFT again / Do not need derive * Fix GC root BUG * Use findExecutable instead of the raw `which` * Come back bytestring * And fix other BUGs Enjoy! :) - - - Metasepi team

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SYB supports genuine gmap. [Was: Polymorphic updating with TC/TFs?]
by oleg＠okmij.org 18 Dec '13

18 Dec '13

adam vogt wrote > Changing type parameters isn't supported by the ones I know (syb), but > you can still fake it: <http://www.haskell.org/haskellwiki/SYB#fmap>. SYB supports the type-changing generic map, of the signature > gmap2 :: forall a b c . (Data a, Data b, > Data (c a), Data (c b), Data (c X)) => > (a -> b) -> c a -> c b It was discovered back in 2008. Please see the following thread starting http://www.haskell.org/pipermail/generics/2008-July/000349.html The fake described in haskellwiki/SYB#fmap with unsafeCoerce is not needed at all. There is a genuine gmap.

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Monad.Reader #23 call for copy
by Edward Z. Yang 18 Dec '13

18 Dec '13

Call for Copy: The Monad.Reader - Issue 23 -------------------------------------------- Whether you're an established academic or have only just started learning Haskell, if you have something to say, please consider writing an article for The Monad.Reader! The submission deadline for Issue 23 will be: **Friday, January 17, 2014** The Monad.Reader ~~~~~~~~~~~~~~~~ The Monad.Reader is a electronic magazine about all things Haskell. It is less formal than journal, but somehow more enduring than a wiki- page. There have been a wide variety of articles: exciting code fragments, intriguing puzzles, book reviews, tutorials, and even half-baked research ideas. Submission Details ~~~~~~~~~~~~~~~~~~ Get in touch with me if you intend to submit something -- the sooner you let me know what you're up to, the better. Please submit articles for the next issue to me by e-mail (ezyang(a)mit.edu) Articles should be written according to the guidelines available from http://themonadreader.wordpress.com/contributing/ Please submit your article in PDF, together with any source files you used. The sources will be released together with the magazine under a BSD license. If you would like to submit an article, but have trouble with LaTeX please let me know and we'll work something out.

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Haskell Singapore Meetup
by Paul Meng 18 Dec '13

18 Dec '13

Hi all, I've already posted on the reddit but forgot to post it here. It's going to be Christmas, and a good way to celebrate it is to have a Haskell meetup. On this Friday, Dec 20. We are going to host it at Google Singapore office. http://www.meetup.com/HASKELL-SG/events/154702892/ There would be a short sharing and have some time to meet with other Haskell programmers (or FP programmer in general) after the talk. If you happen to be in Singapore, welcome to stop by! For people signed up before, notice that we are moving from Zalora to Google's office to have a bigger meeting room. And due to the access policy, please fill out your full name, e-mail and company in the following form. https://docs.google.com/forms/d/1pTQA3eK7Qsxbq_Tw8nPPX6MIUnQuGsm23rT5bfhtw-… Paul Meng

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Proposal: move ansi-terminal to haskell-pkg-janitors
by Roman Cheplyaka 18 Dec '13

18 Dec '13

ansi-terminal is a useful and important package providing colorful console output. It has 50 direct reverse dependencies, and a huge number of indirect ones (through testing frameworks, for example). ansi-terminal was written and maintained by Max Bolingbroke, but he doesn't seem to be active in the Haskell community anymore. The package itself hasn't been updated for a year. Unless he (or someone else) objects, I propose to move ansi-terminal under maintainership of the haskell-pkg-janitors group. Is there any venue for haskell-pkg-janitors, such as a mailing list or IRC channel? Roman

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text 1.0.0.0 producing cabal hell?
by Tillmann Vogt 18 Dec '13

18 Dec '13

Check this out: http://packdeps.haskellers.com/reverse/text 306 outdated dependencies! I am guessing that most libraries could easily change the boundaries to >=0.11 && <1.1 <http://hackage.haskell.org/package/digestive-functors-blaze> because the API hasn't changed a lot. As far as I can see only a function was added. Or is everybody using sandboxing tools? Maybe the author of a library should have the right to change the boundary of all reverse dependencies. So that Brian has to adjust all 306 boundaries if he knows that this would work :-) Just the boundaries, not the code. -Tillmann

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Re: [Haskell-cafe] How to determine the right path to haddock html documentation?
by Roman Cheplyaka 17 Dec '13

17 Dec '13

* Carlo Hamalainen <carlo(a)carlo-hamalainen.net> [2013-12-17 13:10:43+0100] > On 17/12/13 11:32, Roman Cheplyaka wrote: > > > > First, no need to use that fork — all patches have been merged into > > Cabal master at https://github.com/haskell/Cabal. (However, they are not > > released yet, so you still have to build the git version.) > > OK, I've built cabal from github in a clean test account. > > > Second, no, installation won't happen automatically. At the moment you > > have to do that manually, like this: > > > > cabal install --haskell-suite -w hs-gen-iface mtl > > I may be missing something obvious, but which package provides > haskell-suite? I see that it's a group of repositories on github. haskell-suite is not a real package or program. In this context, it's the name of a "virtual compiler" known to cabal. > $ cabal install --haskell-suite -w parsec > cabal: The program haskell-suite is required but it could not be found. The correct command is $ cabal install --haskell-suite -w hs-gen-iface parsec The -w flag lets cabal know that you want to compile using hs-gen-iface, which is a concrete compiler implementing the haskell-suite interface. > > It'd be nice to add a cabal.config option to do that automatically. > > Ditto for --haddock-hyperlink-source which I use all the time so that I > get locally built documentation. Very handy for when I work at a cafe. Yeah, ideally haddock and hscolor should be just separate compilers, just like ghc and hs-gen-iface are. The user would then specify in cabal.config what set of compilers to use for simple `cabal install $pkg`. > I want to make the development process in Vim as smooth as possible. A > newbie should be able to ask "what's this?" or "where is this from?" and > get a quick answer, right there in the editor. Hoogle is very useful but > there should be an editor-integrated solution that works locally and > gives an answer like "this symbol in this file comes from this module on > this system". Then you may be also interested in Ariadne :) https://github.com/feuerbach/ariadne Roman

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Frankfurt Haskell User Group Meetup - Wed. 18.12.
by Peter Althainz 17 Dec '13

17 Dec '13

Dear All, The next meeting of Frankfurt Haskell meetup takes place on Wednesday, 18th of Dec. and is about programming a game with HGamer3D. See game video here: http://www.youtube.com/watch?v=DKq0YsWRPoc and link to invitation here: http://www.meetup.com/Frankfurt-Haskell-User-Group/events/150475792/. Also we will have time for hacking on HWebUI. Peter

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ANNOUNCE: New OpenAL packages
by Sven Panne 17 Dec '13

17 Dec '13

New versions of the OpenAL packages are available on Hackage: * OpenAL 1.5.0.0 * ALUT 2.3.0.0 The main change is that the installation doesn't require autoconf anymore, instead of that, a pure Cabal-based build system is used now. This should make installing the packages on non-Linux systems much easier. Apart from that, uniqueBuffers works now and iOS is a supported platform, thanks to Stephen Blackheath. The packages depend on OpenGL now instead of ObjectName/StateVar/Tensor, because the latter packages were assimilated into OpenGL and there are probably very few programs using OpenAL without OpenGL. Have fun, S.

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haddock for all modules (exposed and other) in a cabalized project?
by Johannes Waldmann 17 Dec '13

17 Dec '13

I have a cabalized project with few "exposed-modules", and a lot of "other-modules". How can I invoke "cabal haddock --hyperlink-source" for *all* modules? - Thanks, J.W.

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Cabal sandbox status in your ZSH prompt
by Daniil Frumin 17 Dec '13

17 Dec '13

Hi everyone, I made a simple script for my zsh setup that allows me to see whether am I in a cabalized sandbox environment or not. On my machine it looks like this: <https://files.app.net/rjphjAG9.png> The script itself is here: <https://gist.github.com/co-dan/7963200> The result of checking for the sandbox is cached, which---as I've realized only moments ago---is probably unnecessary; it updates only when the user performs a `cabal` command or changes a directory. -- Sincerely yours, -- Daniil Frumin

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Fwd: Polymorphic updating with TC/TFs?
by adam vogt 17 Dec '13

17 Dec '13

Hello Hans, You can move the setFoo into a multiparameter type class, to which you can add that constraint: class (HasFoo a, HasFoo b, b ~ NoFoo a (Foo b)) => SetFoo a b where setFoo :: Foo b -> a -> b instance (HasFoo b, b ~ NoFoo (FooT f a) (Foo b)) => SetFoo (FooT f a) b where setFoo f (FooT _ x) = FooT f x In my opinion, that's not as nice as the fundep solution which has less names: class Has s t a b | s -> a, t -> b, s b -> t, t a -> s On the topic of defining setFoo in terms of setFoo', you might be interested in -XDefaultSignatures, which can work with the SetFoo class defined above: class HasFoo a where default setFoo' :: SetFoo a a => Foo a -> a -> a setFoo' = setFoo setFoo' :: Foo a -> a -> a Finally, there seems to be some overlap with generic programming. Changing type parameters isn't supported by the ones I know (syb), but you can still fake it: <http://www.haskell.org/haskellwiki/SYB#fmap>. Regards, Adam On Mon, Dec 16, 2013 at 7:37 PM, Hans Höglund <hans(a)hanshoglund.se> wrote: > Hello, > > I am working with a set of type classes of the following form (http://lpaste.net/97110) The idea is that every such class provide an associated type Foo, and a lens to the Foo in every instance. I.e. this class is used to provide view/set/modify for all types that contain a Foo somewhere deep in its structure. > > For "simple lenses", i.e. functions that does not modify the associated Foo, this is straightforward. However to support polymorphic updates it seems necessary to add another associated type NoFoo, which must be used to constraint the return type of set. > > What bothers me is the redundancy of the two set functions. I would intuitively expect set' to be implemented in terms of set (as it seems to be a restriction of that function), but this is not possible, as the compiler can not deduce that (NoFoo a (Foo a) ~ a). Is there a way to add this constraint to the type class? > > Hans > _______________________________________________ > Haskell-Cafe mailing list > Haskell-Cafe(a)haskell.org > http://www.haskell.org/mailman/listinfo/haskell-cafe

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Building applications with profiling
by Mateusz Kowalczyk 17 Dec '13

17 Dec '13

Greetings, I want to profile the Yi text editor. A quick look on the Haskell wiki suggests that I need --enable-executable-profiling, however enabling that complains that the yi libraries weren't built with profiling. Additionally enabling --enable-library-profiling allows me to recompile the libs but at the very end I get an error about ‘mtl’ not having been built with profiling. >src/library/Yi/Boot.hs:9:8: > Could not find module `Control.Monad.State' > Perhaps you haven't installed the profiling libraries for package >`mtl-2.1.2'? > Use -v to see a list of the files searched for. I can't really recompile mtl with profiling considering that just about every single package on my system seems to depend on it and they would (probably?) all break. Does anyone have any suggestions on how to approach the problem? Am I doing it all wrong? Thanks -- Mateusz K.

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Polymorphic updating with TC/TFs?
by Hans Höglund 17 Dec '13

17 Dec '13

Hello, I am working with a set of type classes of the following form (http://lpaste.net/97110) The idea is that every such class provide an associated type Foo, and a lens to the Foo in every instance. I.e. this class is used to provide view/set/modify for all types that contain a Foo somewhere deep in its structure. For "simple lenses", i.e. functions that does not modify the associated Foo, this is straightforward. However to support polymorphic updates it seems necessary to add another associated type NoFoo, which must be used to constraint the return type of set. What bothers me is the redundancy of the two set functions. I would intuitively expect set' to be implemented in terms of set (as it seems to be a restriction of that function), but this is not possible, as the compiler can not deduce that (NoFoo a (Foo a) ~ a). Is there a way to add this constraint to the type class? Hans

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Alternatives to ThreadScope?
by Justin Bailey 17 Dec '13

17 Dec '13

Are there any other GUI tools that do something similar? Maybe something web-based? Justin

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SBLP 2014 - Preliminary Call for Papers
by Simon Thompson 17 Dec '13

17 Dec '13

PRELIMINARY CALL FOR PAPERS 18th Brazilian Symposium on Programming Languages (SBLP 2014) A member of CBSoft joint conference http://www.ic.ufal.br/evento/cbsoft2014/ to be held in Maceio, Brazil. CBSoft dates are September 28, 2014 to October 3, 2014 (SBLP dates are yet to be decided.) IMPORTANT DATES Paper abstract submission: May 2nd, 2014 Full paper submission: May 9th, 2014 Notification of acceptance: June 13th, 2014 Final papers due: July 4th, 2014 INTRODUCTION The 18th Brazilian Symposium on Programming Languages, SBLP 2014, will be held in Maceio, a beautiful cite in the Northeastern part of Brazil. The conference will happen between September 28th and October 3rd, 2014. SBLP provides a venue for researchers and practitioners interested in the fundamental principles and innovations in the design and implementation of programming languages and systems. SBLP 2014 invites authors to contribute with technical papers related (but not limited) to: * Program generation and transformation, including domain-specific languages and model-driven development in the context of programming languages. * Programming paradigms and styles, including functional, object-oriented, aspect-oriented, scripting languages, real-time, service-oriented, multithreaded, parallel, and distributed programming. * Formal semantics and theoretical foundations, including denotational, operational, algebraic and categorical. * Program analysis and verification, including type systems, static analysis and abstract interpretation. * Programming language design and implementation, including new programming models, programming language environments, compilation and interpretation techniques. SUBMISSIONS Contributions should be written in Portuguese or English. Papers should fall into one of two different categories: full papers, with at most 15 pages, or short papers, with at most 5 pages. Full papers submitted in English will be published in a volume of Lecture Notes in Computer Science (LNCS), by Springer. For this reason, all papers must be prepared using the LNCS template, available at http://www.springer.com/computer/lncs?SGWID=0-164-6-793341-0. We encourage the submission of short papers reporting partial results of on-going master dissertations or doctoral theses. All accepted papers will be published in the conference proceedings distributed in a digital media by the CBSOFT organizers. Submissions should be done through the SBLP 2014 page at EasyChair, which is available at http://www.easychair.org/conferences/?conf=sblp2014. As in previous editions, a journal's special issue, with selected papers from accepted contributions, is anticipated. Selected papers from the 2003 to the 2008 editions of SBLP were published in special issues of the Journal of Universal Computer Science, by Springer. The post-proceedings of SBLP from 2009 to 2012, also with selected papers from the conference, have been published as special issues of Science of Computer Programming, by Elsevier. KEYNOTE SPEAKERS Louis-Noel Pouchet, University of California Los Angeles Fabrice Rastello, INRIA PROGRAMME CHAIR Fernando Magno Quintao Pereira, UFMG PROGRAMME COMMITTEE Alberto Pardo, Universidad de la República Alex Garcia, IME Alvaro Moreira, Federal University of Rio Grande do Sul Andre Rauber Du Bois, Federal University of Pelotas Carlos Camarão, Federal University of Minas Gerais Christiano Braga, Fluminense Federal University Fabio Mascarenhas, Federal University of Rio de Janeiro Fernando Pereira, Federal University of Minas Gerais Fernando Castor, Federal University of Pernambuco Francisco Carvalho-Junior, Federal University of Ceara Hans-Wolfgang Loidl, Heriot-Watt University João Saraiva, University of Minho Joao F. Ferreira, Teesside University Louis-Noel Pouchet, University of California, Los Angeles Lucilia Figueiredo, Federal University of Ouro Preto Luis Barbosa, University of Minho Manuel A. Martins, University of Aveiro Marcello Bonsangue, Leiden University Marcelo Maia, Federal University of Uberlândia Marcelo D'Amorim, Federal University of Pernambuco Mariza Bigonha, Federal University of Minas Gerais Martin Musicante, Federal University of Rio Grande do Norte Noemi Rodriguez, PUC-Rio Peter Mosses, Swansea University Rafael Lins, Federal University of Pernambuco Renato Cerqueira, PUC-Rio Roberto Bigonha, Federal University of Minas Gerais Rodrigo Geraldo, Federal University of Ouro Preto Sandro Rigo, State University of Campinas Sérgio Medeiros, Federal University of Sergipe Simon Thompson, University of Kent Varmo Vene, University of Tartu Simon Thompson | Professor of Logic and Computation School of Computing | University of Kent | Canterbury, CT2 7NF, UK s.j.thompson(a)kent.ac.uk | M +44 7986 085754 | W www.cs.kent.ac.uk/~sjt

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[ANN] IHaskell Update -- Call for Help/Suggestions
by Andrew Gibiansky 17 Dec '13

17 Dec '13

Hey everyone! I'm excited to announce a significant update to IHaskell. I originally announced IHaskell a few months ago, but there's been a few exciting changes: Significantly more stable and less buggy. It's been updated to use the GHC API for parsing and evaluation, so behavior should be very similar to GHCi in most places. You can now defined modules in cells instead of just interactive code. These modules are compiled to object code and loaded and provide fast runtime compared to interactive code. Most important: IHaskell can now load additional packages in order to provide rich display capabilities for specific data types. This means that it can be augmented through separate packages. If you have interest in providing a rich display mechanism for a data type, please consider writing an IHaskell extension package to do so! (If there are any data types that you think would be particularly useful but don't have time to implement yourself, let me know, too!) The extensibility is provided through an IHaskell.Display module. For instance, if you are creating an extension for a particular package foo, you should create a package called ihaskell-foo. This package should contain a module along the following lines: -- The name is important module IHaskell.Display.Foo where import Foo (DataThing) import IHaskell.Display -- Define how to display my data thing instance IHaskellDisplay DataThing where display myDataThing = [ plain "Plain Text output" , html "<b>HTML output</b>"] I would love to work with anyone who's interested in helping create these packages to make IHaskell as useful as possible. In addition, if you have any features you think would really make this more useful or bugs you've found, let me know! If you have any issues with installation, please let me know. I've had some trouble with getting a Hackage-based installation to work, so for now it's just from the Github repository, but I'd be happy to help people individually.

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Data.Vector with stride
by Niklas Hambüchen 17 Dec '13

17 Dec '13

For low-level performance, especially when dealing with images, pixel buffers, camera devices etc, arrays can have a "stride" to align rows to word boundaries. http://en.wikipedia.org/wiki/Stride_of_an_array Data.Vector does not support strides (as mentioned in http://u.arboreus.com/2011/03/how-to-choose-haskell-array-library.html) but it would be nice to have them, especially for Storable vectors and interfacing with C imaging libraries. Is there a particular reason / difficulty that would go against an implementation of a Data.Vector.Storable.Stride and the corresponding generic vector instances?

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Re: [Haskell-cafe] getting source
by Doug McIlroy 16 Dec '13

16 Dec '13

> > It is a shame that when you look something up in Hayoo, > > you can immediately look at the source--but you can't > > You can, but not for every package; try looking up the "map" function, you > will see a link to the source at the right of the page. > > Regards, > Henk-Jan van Tuyl Yes, I said you can look at the source, but not compile it. Hayoo's yellow "source" links get HTML generated from source-- a rendering intended for eyeballs, not compilers. What I suggested is that the HTML include a link to the underlying .hs file. Why should you have to go hassle with git or some other repository, and maybe cabal too, to get code that's right before your eyes? Doug

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Real world project with Cloud Haskell
by jean-christophe mincke 16 Dec '13

16 Dec '13

Hello, Has anybody heard about (or better, made) a real world project using Cloud Haskell? Thank you Regards J-C

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getting source
by Doug McIlroy 16 Dec '13

16 Dec '13

It is a shame that when you look something up in Hayoo, you can immediately look at the source--but you can't

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10 PhD studentships in Nottingham
by Graham Hutton 16 Dec '13

16 Dec '13

Dear all, The School of Computer Science in Nottingham is advertising 10 fully-funded PhD studentships. Applicants in the area of the Functional Programming lab (fp.cs.nott.ac.uk) are encouraged! If you are interested in applying, please contact a potential supervisor in the FP lab prior to submitting your application: Thorsten Altenkirch - constructive logic, proof assistants, type theory, category theory, lambda calculus, quantum computing. Venanzio Capretta - type theory, mathematical logic, corecursive structures, proof assistants, dependently-typed programming. Graham Hutton - program construction and verification, category theory, recursion operators, coinductive types. Henrik Nilsson - functional reactive programming, modelling and simulation languages, domain-specific languages. Best wishes, Graham +-----------------------------------------------------------+ 10 Fully-Funded PhD Studentships School of Computer Science University of Nottingham, UK Applications are invited for up to ten fully-funded PhD studentships in the School of Computer Science at the University of Nottingham, starting on 1st October 2014. The topics for the studentships are open, but should relate to the interests of one of the School’s research groups: Agents Lab; Automated Scheduling, Optimisation and Planning; Computer Vision Lab; Functional Programming Lab; Intelligent Modelling and Analysis; Mixed Reality Lab; Networked Systems. The studentships are for three years and include a stipend of £13,726 per year and tuition fees, and are available to students of any nationality. Applicants are normally expected to have a first-class Undergraduate or Masters degree in Computer Science or a related discipline, and should discuss their interest and obtain the support of a potential supervisor in the School before applying. To apply, please submit the following items by email to <Christine.Fletcher(a)nottingham.ac.uk>: (1) a brief covering letter that describes your reasons for wishing to pursue a PhD, any ideas you have regarding possible areas or topics, and the name of a potential supervisor; (2) a copy of your CV, including your actual or expected degree class(es), and results of all University examinations; (3) an example of your technical writing, such as a project report or dissertation; (4) contact details for two academic referees. Closing date for applications: 10th January 2014 +-----------------------------------------------------------+ -- Prof Graham Hutton Functional Programming Lab School of Computer Science University of Nottingham, UK http://www.cs.nott.ac.uk/~gmh This message and any attachment are intended solely for the addressee and may contain confidential information. If you have received this message in error, please send it back to me, and immediately delete it. Please do not use, copy or disclose the information contained in this message or in any attachment. Any views or opinions expressed by the author of this email do not necessarily reflect the views of the University of Nottingham. This message has been checked for viruses but the contents of an attachment may still contain software viruses which could damage your computer system, you are advised to perform your own checks. Email communications with the University of Nottingham may be monitored as permitted by UK legislation.

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RFC: Top level mutable state in terms of pure-function initialization?
by EatsKittens 16 Dec '13

16 Dec '13

A pure function (enumToIORef :: (Enum a, Defaultable b) => a -> IORef b). This function returns referentially transparently an IORef as a function of its "seed" with the guarantee that the IORef returned is identical if and only if the seed is. This function can be used to implement top level mutable state in a module. The module can specifically create an enumerated type for this and not export it, thereby removing any possibility of another module passing the seed type and conflicting. The Defaultable class is added in this case to implement only a single method (defaultValue :: Defaultable a => a -> a). This is conceptionally the 'simplest' value of the type, such as the empty list, the number 0, False, the null character &c. The IORef returned by enumToIORef would be initialized before being written to to this specific default value of its type. This approach is chosen because it is impossible to initialize it to user specified value because enumToIORef can be called twice with the same seed but a different initial value. In the alternative it is also possible to do without the default value and say the IORef returned is the same if and only if the seed and the initial value given are the same. Allowing the function to remain referentially transparent as well. This would probably require for good semantics the underlying type of the IORef to be a member of EQ...? All this would of course require that newIORef and enumToIORef never produce the same IORef. Aside its limitations of the type IORef's initialized with this method can carry, I do believe they cover the vast majority of use cases of top level mutable state? Caveats?

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[ANN] Canberra -- Introduction to Functional Programming course (free)
by Tony Morris 16 Dec '13

16 Dec '13

*Title: *Introduction to Functional Programming *Presenters:* Mark Hibberd and Tony Morris *When: * Tuesday 4th, Wednesday 5^th & Thursday 6^th February, 9.00am -- 5.00pm (lunch will be provided) *Where: *NICTA CRL, Tower A, 7 London Circuit, Canberra ACT *Cost:* Free *Abstract:*NICTA will be hosting a hands-on, three day Introduction to Functional Programming, for interested participants (internal and external). We will be using the Haskell programming language for our journey over the three days and this session requires no prior experience with functional programming. You will be required to bring a suitable development machine (portable) for working through the exercises. You will also need to install Glasgow Haskell Compiler (http://www.haskell.org/ghc/) version 7 or higher on that machine. There are no other primary requirements. Each session will be instructed by Mark Hibberd (NICTA) and Tony Morris (NICTA), to help you along your path of FP discovery, wherever that might be. If you are interested in attending this course, please email your EOI to the below email address. In your response, it is very helpful for us to understand your goals in order to make the best of the time we will have, so please take the time to answer the below questions in your response. Your answers will not be shared- just used to construct the course structure/ material. Attendees will be selected based on the answers provided: 1. How would you rate your level of understanding of functional programming? 2. What would you hope to get out of the session? *Expression of Interest:*To haylee.alder(a)nicta.com.au <mailto:haylee.alder@nicta.com.au> by *Friday 24 January, 5pm*.

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