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TFPIE - Trends in Functional Programming in Education 2017 - Deadline extended to 17 May
by Simon Thompson 09 May '17

09 May '17

After a number of requests, we have extended the deadline for TFPIE 2017 to 17 May. Please consider submitting if you’re interested in hearing about how to get the functional message shared more widely. A particular topic of this year's TFPIE will be MOOCs and other online learning and, as well as a session on this, we're delighted to announce that Heather Miller of EFPL and Northeastern University will be giving a keynote on this topic. Heather works on and around the Scala programming language and is Executive Director of the Scala Center. We'll also have Yann Regis-Gianas and Benjamin Canou from the OCaml MOOC team, Jeremy Singer (Haskell), and Simon Thompson (Erlang). TFPIE 2017 - DEADLINE EXTENDED TO 17 MAY Trends in Functional Programming in Education, 2017 https://www.cs.kent.ac.uk/people/staff/sjt/TFPIE2017/ The sixth workshop on Trends in Functional Programming in Education, 2017, which is to be held on the Canterbury campus of the University of Kent on Thursday, 22 June, following the 2017 TFP meeting on 19–21 June. TFPIE workshops have previously been held in St Andrews, Scotland (2012), Provo Utah, USA (2013), Soesterberg, The Netherlands (2014), and Sophia-Antipolis, France (2015), College Park, USA (2016). The goal of TFPIE is to gather researchers, teachers and professionals that use, or are interested in the use of, functional programming in education. TFPIE aims to be a venue where novel ideas, classroom-tested ideas and work-in-progress on the use of functional programming in education are discussed. The one-day workshop will foster a spirit of open discussion by having a review process for publication after the workshop. The program chair of TFPIE 2017 will screen submissions to ensure that all presentations are within scope and are of interest to participants. After the workshop, presenters will be invited to submit revised versions of their articles for publication in the journal Electronic Proceedings in Theoretical Computer Science (EPTCS). Final call for papers TFPIE 2017 welcomes submissions describing techniques used in the classroom, tools used in and/or developed for the classroom and any creative use of functional programming (FP) to aid education in or outside Computer Science. Topics of interest include, but are not limited to: - FP and beginning CS students - FP and Computational Thinking - FP and Artificial Intelligence - FP in Robotics - FP and Music - Advanced FP for undergraduates - FP in graduate education - Engaging students in research using FP - FP in Programming Languages - FP in the high school curriculum - FP as a stepping stone to other CS topics - FP and Philosophy - The pedagogy of teaching FP - FP and e-learning: MOOCs, automated assessment etc. - Best Lectures – more details below In addition to papers, we are requesting best lecture presentations. What’s your best lecture topic in an FP related course? Do you have a fun way to present FP concepts to novices or perhaps an especially interesting presentation of a difficult topic? In either case, please consider sharing it. Best lecture topics will be selected for presentation based on a short abstract describing the lecture and its interest to TFPIE attendees. Submission Potential presenters are invited to submit an extended abstract (4-6 pages) or a draft paper (up to 16 pages) in EPTCS style. The authors of accepted presentations will have their preprints and their slides made available on the workshop's website. Papers and abstracts can be submitted via easychair at the following link: https://easychair.org/conferences/?conf=tfpie2017 After the workshop, presenters will be invited to submit (a revised version of) their article for review. The PC will select the best articles for publication in the journal Electronic Proceedings in Theoretical Computer Science (EPTCS). Articles rejected for presentation and extended abstracts will not be formally reviewed by the PC. Programme committee Dr Laura Castro, University of A Coruña Prof Ralf Lämmel, University of Koblenz-Landau Dr Elena Machkasova, University of Minnesota, Morris Prof Michel Mauny, Inria, Paris Dr Jeremy Singer, University of Glasgow Prof Simon Thompson, University of Kent (chair) Important dates Submissions of draft papers: 17 May, 2017 Notification: 22 May, 2017 Registration: 11 June, 2017 Workshop: 22 June 2017 Submission for formal review: 18 August, 2017 Notification of acceptance: 6 October, 2017 Camera ready paper: 3 November, 2017 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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Bug in random shuffle algorithm
by David Turner 09 May '17

09 May '17

https://wiki.haskell.org/Random_shuffle says: Here's a variation using the MonadRandom package: import Control.Monad import Control.Monad.ST import Control.Monad.Random import System.Random import Data.Array.ST import GHC.Arr shuffle :: RandomGen g => [a] -> Rand g [a] shuffle xs = do let l = length xs rands <- take l `fmap` getRandomRs (0, l-1) let ar = runSTArray $ do ar <- thawSTArray $ listArray (0, l-1) xs forM_ (zip [0..(l-1)] rands) $ \(i, j) -> do vi <- readSTArray ar i vj <- readSTArray ar j writeSTArray ar j vi writeSTArray ar i vj return ar return (elems ar) But this doesn't yield a uniformly-chosen random permutation of its input, because at the i'th step the first `i` elements are not fixed as they are in the other algorithms on that page. Cheers, David

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Re: [Haskell-cafe] [perl #129843] [LTA] Indexing on a Str throws generic “out of range” message which is less than awesome (“hello”[2])
by Joachim Durchholz 09 May '17

09 May '17

Am 08.05.2017 um 23:00 schrieb Brandon Allbery: > > On Mon, May 8, 2017 at 4:49 PM, Joachim Durchholz <jo(a)durchholz.org > <mailto:jo@durchholz.org>> wrote: > > If the mental model for Perl6 strings is "array of characters" though > > Perl has never had that mental model, is my point. Right, I should have written "is supposed to evolve to" instead of "is". Array of characters may be a useful abstraction to have in Perl6, or not (see below). > It's generally > imported by folks who come from languages where strings *are* "arrays of > characters" --- and where that model has a strong tendency to cause > problems. (See Python 3's struggles with Unicode as an example. And > C/C++, well, don't even get me started. Some of these struggles originate from equating bytes with characters. Since Perl6 is more or less a clean slate, it can avoid these. Other struggles originate from the structure of Unicode: it defines multiple levels of sequences, each useful for different tasks: - code points - graphemes - characters (various normalizations exist) - word parts (for line breaking) - words - sentences - paragraphs and possible a few more. Ideally, developers will be able to use the same API structure at each level, maybe with the exception of the grapeme level where Perl6 has its native representation (the better the API, the less of such implementation details is visible and relevant to the programmer). > Bytes stopped being the basis of > characters even *before* Unicode. C and C++ are still struggling to > understand that. I think you're being unfair to them. The issues are actually well-understood in the C++ arena, as demonstrated by the ICU library. It's just that language evolution is constrained by legacy, plus possibly short-sighed decisions by compiler makers. Also, C++ (by necessity) evolves slower than Unicode. Under these conditions, Unicode support in a library is actually preferrable to anything inside the language, it's enough if the language can interoperate with the library.

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[ANN] gonimo web-based baby monitor has launched!
by Robert Klotzner 09 May '17

09 May '17

Hi to all Haskell-er parents out there! Always hated that your baby monitor is the only thing left in your household not coded in Haskell? Well, don't worry no more! Gonimo is here! Visit gonimo.com <https://gonimo.com> and have a baby monitor coded in Haskell! All you need is a recent web-browser (Chrome works best) on any non iOS platform! :-) Source code on github <https://github.com/gonimo/gonimo>! Hope you like it! Feedback, very welcome! Uh and we have a facebook page too! facebook.com/mygonimo ! If you like our baby monitor consider a like or even share - it is pretty hard with no money to reach potential users, so this would really be awesome! Best regards, Robert

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Parse stream using an external template for rules?
by Brian Jones 09 May '17

09 May '17

I'm not completely sure what I am looking for so I figured I'd ask the community. I have a project which reads data from a telnet stream (I wrote a pipes-network[1] library to handle this), however, rather than hard code the parsing rules with something like attoparsec (as I have done in my example) I'd like to define a template language which reads in a file with the template definitions that describes what to parse instead and use that inside the parser step. What tools and approaches would you recommend in this case? Or alternatively, a better solution? Thanks, Brian [1] https://github.com/alasconnect/pipes-telnet

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Language extension proposal: aspects
by MarLinn 08 May '17

08 May '17

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Deadline extension may 15: Trends in Functional Programming, 19-21 june 2017, University of Kent, Canterbury
by Peter Achten 08 May '17

08 May '17

TFP 2017 EXTENSION: Deadline extension until Monday, 15 May (anywhere on earth). -------------------------------------------------------------------------------- We encourage anyone who wants to present their work at TFP in Canterbury, England this June to submit a 2-10 page abstract if time is too short to put together a full paper. ----------------------------- F I N A L C A L L F O R P A P E R S ----------------------------- ======== TFP 2017 =========== 18th Symposium on Trends in Functional Programming 19-21 June, 2017 University of Kent, Canterbury https://www.cs.kent.ac.uk/events/tfp17/index.html The symposium on Trends in Functional Programming (TFP) is an international forum for researchers with interests in all aspects of functional programming, taking a broad view of current and future trends in the area. It aspires to be a lively environment for presenting the latest research results, and other contributions (see below). Authors of draft papers will be invited to submit revised papers based on the feedback receive at the symposium. A post-symposium refereeing process will then select a subset of these articles for formal publication. TFP 2017 will be the main event of a pair of functional programming events. TFP 2017 will be accompanied by the International Workshop on Trends in Functional Programming in Education (TFPIE), which will take place on 22 June. The TFP symposium is the heir of the successful series of Scottish Functional Programming Workshops. Previous TFP symposia were held in * Edinburgh (Scotland) in 2003; * Munich (Germany) in 2004; * Tallinn (Estonia) in 2005; * Nottingham (UK) in 2006; * New York (USA) in 2007; * Nijmegen (The Netherlands) in 2008; * Komarno (Slovakia) in 2009; * Oklahoma (USA) in 2010; * Madrid (Spain) in 2011; * St. Andrews (UK) in 2012; * Provo (Utah, USA) in 2013; * Soesterberg (The Netherlands) in 2014; * Inria Sophia-Antipolis (France) in 2015; * and Maryland (USA) in 2016. For further general information about TFP please see the TFP homepage. (http://www.tifp.org/) == SCOPE == The symposium recognizes that new trends may arise through various routes. As part of the Symposium's focus on trends we therefore identify the following five article categories. High-quality articles are solicited in any of these categories: Research Articles: leading-edge, previously unpublished research work Position Articles: on what new trends should or should not be Project Articles: descriptions of recently started new projects Evaluation Articles: what lessons can be drawn from a finished project Overview Articles: summarizing work with respect to a trendy subject Articles must be original and not simultaneously submitted for publication to any other forum. They may consider any aspect of functional programming: theoretical, implementation-oriented, or experience-oriented. Applications of functional programming techniques to other languages are also within the scope of the symposium. Topics suitable for the symposium include, but are not limited to: Functional programming and multicore/manycore computing Functional programming in the cloud High performance functional computing Extra-functional (behavioural) properties of functional programs Dependently typed functional programming Validation and verification of functional programs Debugging and profiling for functional languages Functional programming in different application areas: security, mobility, telecommunications applications, embedded systems, global computing, grids, etc. Interoperability with imperative programming languages Novel memory management techniques Program analysis and transformation techniques Empirical performance studies Abstract/virtual machines and compilers for functional languages (Embedded) domain specific languages New implementation strategies Any new emerging trend in the functional programming area If you are in doubt on whether your article is within the scope of TFP, please contact the TFP 2017 program chairs, Scott Owens and Meng Wang. == BEST PAPER AWARDS == To reward excellent contributions, TFP awards a prize for the best paper accepted for the formal proceedings. TFP traditionally pays special attention to research students, acknowledging that students are almost by definition part of new subject trends. A student paper is one for which the authors state that the paper is mainly the work of students, the students are listed as first authors, and a student would present the paper. A prize for the best student paper is awarded each year. In both cases, it is the PC of TFP that awards the prize. In case the best paper happens to be a student paper, that paper will then receive both prizes. == PAPER SUBMISSIONS == Acceptance of articles for presentation at the symposium is based on a lightweight peer review process of extended abstracts (4 to 10 pages in length) or full papers (20 pages). The submission must clearly indicate which category it belongs to: research, position, project, evaluation, or overview paper. It should also indicate which authors are research students, and whether the main author(s) are students. A draft paper for which ALL authors are students will receive additional feedback by one of the PC members shortly after the symposium has taken place. We use EasyChair for the refereeing process. Papers must be submitted at: https://easychair.org/conferences/?conf=tfp17 Papers must be written in English, and written using the LNCS style. For more information about formatting please consult the Springer LNCS web site: http://www.springer.com/computer/lncs?SGWID=0-164-6-793341-0 == INVITED SPEAKERS == Conor McBride University of Strathclyde (UK) Cătălin Hriţcu INRIA Paris (FR) == IMPORTANT DATES == Submission of draft papers: ***15 May, 2017*** extension Notification: 12 May, 2017 Registration: 11 June, 2017 TFP Symposium: 19-21 June, 2017 Student papers feedback: 29 June, 2017 Submission for formal review: 2 August, 2017 Notification of acceptance: 3 November, 2017 Camera ready paper: 2 December, 2017 == PROGRAM COMMITTEE == Co-Chairs Meng Wang University of Kent (UK) Scott Owens University of Kent (UK) PC Jeremy Yallop University of Cambridge (UK) Nicolas Wu University of Bristol (UK) Laura Castro University of A Coruña (ES) Gabriel Scherer Northeastern University (US) Edwin Brady University of St Andrews (UK) Janis Voigtländer Radboud University Nijmegen (NL) Peter Achten Radboud University Nijmegen (NL) Tom Schrijvers KU Leuven (BE) Matthew Fluet Rochester Institute of Technology (US) Mauro Jaskelioff CIFASIS/Universidad Nacional de Rosario (AG) Patricia Johann Appalachian State University (US) Bruno Oliveira The University of Hong Kong (HK) Rita Loogen Philipps-Universität Marburg (GE) David Van Horn University of Marylan (US) Soichiro Hidaka Hosei University (JP) Michał Pałka Chalmers University of Technology (SE) Sandrine Blazy University of Rennes 1 - IRISA (FR)

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[ANN] New release of SBV, now with optimization
by Levent Erkok 08 May '17

08 May '17

I'm happy to announce a new release of SBV (v6.0); a library for seamlessly integrating SMT solvers with Haskell: http://hackage.haskell.org/package/sbv <https://hackage.haskell.org/package/sbv> This version brings optimization features to SBV, where arithmetic goals can be minimized or maximized. The algorithms employed are particularly suitable for linear-optimization problems, over bounded/unbounded integers and reals. Multiple objective functions with optimization priorities are also supported: http://hackage.haskell.org/package/sbv-6.0/docs/Data-SBV.html#g:44 Objective values that assume their optimal values at infinity and epsilon are also supported, allowing the user to express arbitrary combinations of goals. Furthermore, soft-goals (i.e., those that can be violated with a user-specified penalty) are included as well. Such goals can be used to expressed "nice-to-have" constraints, for instance as they appear in classic scheduling problems. (Optimization is currently only supported by the z3-backend, and leverages the features of the z3 SMT solver. Please make sure you get a fresh copy of it from github <https://github.com/Z3Prover/z3>.) A few basic examples: - Basic linear optimization over reals <https://hackage.haskell.org/package/sbv-6.0/docs/Data-SBV-Examples-Optimiza…> - Workshop product allocation <https://hackage.haskell.org/package/sbv-6.0/docs/Data-SBV-Examples-Optimiza…> - Allocating virtual-machines in data-centers <https://hackage.haskell.org/package/sbv-6.0/docs/Data-SBV-Examples-Optimiza…> This release also comes with a number of other changes/features, including support for user given tactics, mainly aimed for advanced users. See here <https://hackage.haskell.org/package/sbv-6.0/changelog> for details. Bug reports, as always, are most welcome. -Levent.

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Re: [Haskell-cafe] Seeking Help with IHaskell Maintenance/Development
by Jonathan Wheaton 07 May '17

07 May '17

As a Haskell newbie and someone who uses IHaskell as a way of exploring Haskell from anywhere (work, various laptops and Chromebooks at home, my mobile phone even), I would be really sad to see IHaskell go away. I'm very much hoping the project can find a maintainer, as it's been invaluable to me. Jonathan Wheaton On May 7, 2017 11:52 AM, "Andrew Gibiansky" <andrew.gibiansky(a)gmail.com> wrote: Hey folks, For the past several months, I have not been able to put any effort into maintaining IHaskell, a front-end for Jupyter for Haskell. I do not know how useful IHaskell has been in the past to the community, but as it becomes more and more outdated it becomes less useful. If anyone is interested in helping out (or taking over) IHaskell maintenance and development, please let me know. Best, Andrew -- – Andrew _______________________________________________ Haskell-Cafe mailing list To (un)subscribe, modify options or view archives go to: http://mail.haskell.org/cgi-bin/mailman/listinfo/haskell-cafe Only members subscribed via the mailman list are allowed to post.

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[ANN] ble: Bluetooth Low Energy in Haskell
by Julian K. Arni 07 May '17

07 May '17

Dear list, I've released the package 'ble' a little while ago, but hadn't announced it so far because I wanted to make sure the API stabilized somewhat, and at least some bugs were addressed, in the course of dealing with our own needs. But now feels like a good time to announce it. 'ble' allows writing Bluetooth Low Energy peripherals in Haskell (and soon, centrals too). Currently only Linux (with Bluez >= 5.41) is supported. Mostly it exposes the GATT API. The README (in the github repo and in the Hackage main page) provide a simple example application. Github: https://github.com/plow-technologies/ble Hackage: http://hackage.haskell.org/package/ble Enjoy, ~~~ Julian Arni Haskell Consultant https://turingjump.com/

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Seeking Help with IHaskell Maintenance/Development
by Andrew Gibiansky 07 May '17

07 May '17

Hey folks, For the past several months, I have not been able to put any effort into maintaining IHaskell, a front-end for Jupyter for Haskell. I do not know how useful IHaskell has been in the past to the community, but as it becomes more and more outdated it becomes less useful. If anyone is interested in helping out (or taking over) IHaskell maintenance and development, please let me know. Best, Andrew -- – Andrew

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Partial type family application
by mniip 06 May '17

06 May '17

So I've been thinking of a type system extension: partial type family application. If we look at the type system used by modern GHC, in it, type family application is very distinct from constructor/constraint application: it is somewhat opaque in the sense that a type family must always appear fully applied. As such, it doesn't make sense to talk about a type family's kind, if we have: type family Id (a :: *) :: * where Id x = x then saying that 'Id :: * -> *' would be wrong, because Id cannot be used interchangeably with things that are truly of kind * -> *, such as Maybe or []. The reason for the "fully applied" restriction is that if we allowed partially applied type functions, then their equality would be undecidable. Still, I think, in a lot of cases we could benefit from partially applied type functions, even without extensional equality. Writing type level list folds, filters, zips, you name it. As stated above, we can't add the proposition 'Id :: * -> *' to our type system, so, what if, instead, we added a different kind of arrow kind for type families? I like the look of (~>), so 'Id :: * ~> *'. (~>) :: * -> * -> * This rule of inference, similar to the usual, would supersede all the type family kinding rules: f :: k ~> l, x :: k ------------------- f x :: l As such, the juxtaposition operator would very clearly have two different "kinds": (k -> l) --> k --> l and (k ~> l) --> k --> l, and there is no N-ary "type family application" operator. In order for the type checker to not fall apart, we need to have at least intesional (structural) equality on (~>), which we can have because it is decidable. We could then write stuff like type family Foldr (f :: k ~> l ~> l) (z :: l) (xs :: [k]) :: l where Foldr f z '[] = z Foldr f z (x ': xs) = f x (Foldr f z xs)

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Generalized concatMap for lenses?
by Tyson Whitehead 06 May '17

06 May '17

I am writing some code to do some web-page parsing using the lens library. The folded (or traverse) functions let me go sequence -> lens fold It would be nice to be able to go back again lens fold -> sequence The general idea being move it into a lens-fold sequence representation, work with it there, and then recover the original sequence representation. As a more concrete example, the following works for lists (folded .) :: Getter s [a] -> Fold s a (to . toListOf) :: Fold s a -> Getter s [a] I think I'm maybe thinking of something like a generalized concatMap for lenses magic :: Fold s a -> Getter (f s) (f a) Possibly there is already a function for this or some other way it should be done? Haven't found it yet though, so thought I would ask the list for some enlightenment. Thanks! -Tyson

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Functor instance for FunPB
by Alex Wede 06 May '17

06 May '17

Hey Everyone, ich have a algebraic data type: data FunPB a b = FunPB { runFunPB :: a -> (a,[b]) } I got a Monoid Instance instance Monoid (FunPB a b) where mempty = FunPB $ \k -> (k,mempty) mappend pb1 pb2 = FunPB $ \n -> (,) n $ msum . (<$>) (uncurry (flip const).((flip runFunPB) n)) $ [pb1,pb2] Now I need to write a functor instance instance Functor (FunPB a) where fmap f b = ? How can I map over a->(a,[b])? Lg Alex

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Hunting for ghci manual input vs. file input differences again
by MarLinn 05 May '17

05 May '17

Hi, I've been working on a kind of constrained version of Data.Dynamic: data Dynamic (c :: * -> Constraint) where Dynamic :: (Typeable a, c a) => a -> Dynamic c The idea is that Data.Dynamic gives up all compile time type information. In this variant I can at least keep a bit of the information around that I have. (In fact I can even "lift" a type into a constraint, thereby keeping /all/ information.) Most of my functions are nailed down, including mappings and traversals. But one group of functions eludes me: functions to change only the constraint, while keeping the value. Here is one of my goal types: castDynamic :: ( Typeable a, c a, d a ) => Dynamic c -> Dynamic d I'm pretty sure I'll have to sprinkle in a Proxy a, but so be it. I've thrown all typing tricks at this function that I know of, from unsafeCoerce over case-of instead of pattern matching, to ScopedTypeVariables. But I couldn't convince ghci to accept my code. So I tried something simpler. castDynamic' :: (Typeable a, c a) => Dynamic Show -> Maybe (Dynamic c) Here's where it gets funny: I can implement this function in ghci interactively just fine. >>> :t \(d :: Dynamic Show) -> case d of Dynamic a -> Dynamic <$> cast a \(d :: Dynamic Show) -> case d of Dynamic a -> Dynamic <$> cast a :: (Typeable a, c a) => Dynamic Show -> Maybe (Dynamic c) But when I enter the exact same code in a file and load it, ghci balks at me because a is too ambiguous. Again, I've tried if it's the monomorphism restriction, or if I need to sprinkle in more (scoped) signatures or explicit forall's etc… nothing helped. What is the difference here? Am I missing an extension? Am I doing something I shouldn't and the interactive mode is just doing me a favor? There was a discussion on this list less than a month ago where it was mentioned that ghci handles polymorphic types differently depending on the source of the code. Is there some documentation on these differences? Any help would be appreciated. Cheers, MarLinn

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http-client(-tls) or http-conduit?
by Baojun Wang 05 May '17

05 May '17

Hi cafe, It seems both(all) packages are actively maintained, however, they seem to provide a lots of similar functionalities, is there any preferences to use any one of them, and the reason why (Personally I'd prefer the former because of familiarity)? I've read [ https://haskell-lang.org/library/http-client] but it doesn't have recommendation. Thanks baojun

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Re: [Haskell-cafe] Foldable for (,)
by Olaf Klinke 04 May '17

04 May '17

Look at the Stream functor in Data.Stream [1]. Below I will argue by examples that while both Foldable and Traversable instances can be defined, the Foldable instance is less likely to produce terminating functions. Streams can be given a Traversable instance easily: instance Traversable Stream where sequenceA (Cons fa fas) = liftA2 Cons fa (sequenceA fas) For some applicatives this will not terminate. For streams of Maybes, sequenceA will either yield Just an infinite stream or return Nothing. Streams of IO actions also seem fine. A possible Foldable instance would suffer the same termination issues due to recursion. But with a monoid, folds over a stream will terminate less often, e.g. instance Foldable Stream where foldMap f (Cons x xs) = mappend (f x) (foldMap f xs) Then, all (xs :: Stream Bool) will diverge for the constant True stream and terminate for all others. -- Olaf [1] http://hackage.haskell.org/package/Stream-0.4.7.2/docs/Data-Stream.html

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Haskell type declaration summary
by Andrew Butterfield 04 May '17

04 May '17

Dear Haskellers, any quick and easy way to extract all the type declarations from a Haskell source file? (for easy reference) Regards, Andrew Butterfield School of Computer Science & Statistics Trinity College Dublin 2, Ireland

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Re: [Haskell-cafe] Haskell type declaration summary
by Andrew Butterfield 04 May '17

04 May '17

Hi Kevin, yes - I can do that, but it is tedious to issue each command, and I may not remember what all the types are called (I know that :browse will tell me what things exist in the current module with a capital letter) Also I want to be able to do this for a file different to the one currently loaded in GHCi. Something along the lines of (assuming a unix shell): $> showtypes MyBigMonsterHaskellFile.hs data X = A | B type Name = String newtype Y = Z Name .... $> (maybe with a blank line for each one..) Has no-one rustled up something like this - or do I need to look into Haskell parsing...? Cheers, Andrew > On 4 May 2017, at 16:30, Kevin Quick <quick(a)sparq.org> wrote: > > > You can use ghci's browse: > > $ ghci > Prelude> import Data.Maybe > Prelude Data.Maybe> :browse Data.Maybe > ... > Prelude Data.Maybe> :l MyFile.hs > MyFile Data.Maybe> :browse MyFile > ... > > Andrew Butterfield writes: > >> Dear Haskellers, >> any quick and easy way to extract all the type declarations from a Haskell source file? >> (for easy reference) >> >> Regards, >> >> Andrew Butterfield >> School of Computer Science & Statistics >> Trinity College >> Dublin 2, Ireland >> >> _______________________________________________ >> Haskell-Cafe mailing list >> To (un)subscribe, modify options or view archives go to: >> http://mail.haskell.org/cgi-bin/mailman/listinfo/haskell-cafe >> Only members subscribed via the mailman list are allowed to post. > Andrew Butterfield School of Computer Science & Statistics Trinity College Dublin 2, Ireland

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How should I view this file? It looks like literate Haskell but isn't that file type.
by Jeffrey Brown 04 May '17

04 May '17

I am looking at Text.Markdown. The Types.hs file[1] looks like it's got comments that are meant to be viewed as some form other than plain text -- for instance, , msAddHeadingId :: Bool -- ^ If @True@, an @id@ attribute is added to the heading tag with the value equal to -- the text with only valid CSS identifier characters. -- -- > ## Executive Summary -- -- > <h2 id="executive-summary">Executive Summary</h2> -- -- Default: @False@ -- -- Since 0.1.13 I thought it might be literate Haskell, but the file ends in .hs, not .lhs. How should I view it? Preferably in Emacs? [1] https://github.com/snoyberg/markdown/blob/master/Text/Markdown/Types.hs -- Jeff Brown | Jeffrey Benjamin Brown Website <https://msu.edu/~brown202/> | Facebook <https://www.facebook.com/mejeff.younotjeff> | LinkedIn <https://www.linkedin.com/in/jeffreybenjaminbrown>(spammy, so I often miss messages here) | Github <https://github.com/jeffreybenjaminbrown>

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customize ghci error msg
by Johannes Waldmann 04 May '17

04 May '17

Dear Cafe. I have a "stack repl" which loads 841 modules in ghci. I have to do :set prompt "> " because the default prompt shows all modules loaded, and I never see a value or an error message without an enourmous amount of scrolling. But, even with this prompt - when I get some error on ":r", ghci says "... Failed, modules loaded: ..." and again I have to scroll back five miles. How could I change this message? - Thanks, J.W. https://downloads.haskell.org/~ghc/latest/docs/html/users_guide/ghci.html#g…

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Re: [Haskell-cafe] [Biohaskell] hash map/associative structure
by Ketil Malde 04 May '17

04 May '17

> I know it may be a long shot, but did you consider using columnar data store like Apache Arrow? Arrow might be an option, but is there a Haskell interface? (Googling gives the obvious hits regarding arrows, and Google doesn't seem to care about me adding +apache to the search, it gives me result where "+apache" is overstruck.) > Without knowing more about your application it is a bit difficult to produce more hints. > What is your application? The short story is that I extract a number of 64-bit values from my data, and want to maintain frequency counts for each unique value. So there'll be on the order of 10^9 (plus/minus an order of magnitude) unique values, with counts ranging from one to a few million (and large values being rare). The long explanation is that I'm doing k-mer counts for molecular sequences, breaking DNA sequence data into overlapping words of fixed size (the parameter k), and counting their occurrences. I encode them as Word64, using two bits per nucleotide (the alphabet is A, C, G, and T). This is of course a fairly staple thing to do, and there is no lack of alternative programs that do it - but I'd like mine to work anyway, and it annoys me to have run into this particular bug. Whether it is my own fault, in the Judy FFI, the GHC runtime or libraries, the libjudy code, GHC compilation issues, or a hardware error. -k -- If I haven't seen further, it is by standing in the footprints of giants

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Foldable for (,)
by Jonathon Delgado 04 May '17

04 May '17

I sent the following post to the Beginners list a couple of weeks ago (which failed to furnish an actual concrete example that answered the question). Upon request I'm reposting it to Café: I've seen many threads, including the one going on now, about why we need to have: length (2,3) = 1 product (2,3) = 3 sum (2,3) = 3 or (True,False) = False but the justifications all go over my head. Is there a beginner-friendly explanation for why such seemingly unintuitive operations should be allowed by default?

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Typing Haskell in Haskell experience
by Christopher Done 03 May '17

03 May '17

I’ve been working through Typing Haskell in Haskell in detail ( https://gist.github.com/chrisdone/0075a16b32bfd4f62b7b) and I noticed that if I change e.g. SourcePrelude.hs from the Hackage package ( http://hackage.haskell.org/package/thih) to have a declaration like this: [("printZ", Just (Forall [] ([] :=> (tString))), [([], ap [econst showMfun, econst (("Z" :>: toScheme (TCon (Tycon "Nat" Star))))])])], In other words printChar = show (Z :: Nat) Where Z is neither defined nor an instance of Show, it type checks just fine. If I replace it with e.g. toScheme (TVar(Tyvar "k" Star)) i.e. “some thing of type k“, then it complains that the instance is ambiguous, which is true. So it seems that THIH will accept any type as an instance of any class without complaint as long as all the type variables have been filled in with the correct kind. This came as a surprise to me, as I’m using it in a project. There is apparently code in the type checker that pays attention to the class environment, and you provide instances to it, but it doesn’t seem to care what instances are provided or not. I believe I’ll have to do some extra work to check that the instances actually exist and are full resolved. I can’t tell whether this is a bug or intended behavior. I tried emailing the author of THIH but his email bounced back. Frankly the actual interesting bit of the type checker — the bit where we resolve class instances — is actually the hardest bit for me to read and the bit I’d like more exposition on. I’ve written a tokenizer, parser, renamer and thanks to THIH an inferer, and a stepper in a small dialect of Haskell I’m calling Duet. There’s an example here: http://chrisdone.com/toys/duet-gamma/ You can see the problem illustrated if you type e.g. the following in the top-left: data Nat = Z | S Natmain = show Z The type inferred is: main = ((show :: (Show Nat) => Nat -> String) (Z :: Nat) :: (Show Nat) => String) Which is at least enough information for me to do a lookup and insert an instance dictionary. But I sort of would have expected the type checker to say “no instance”. It does explicitly say that you have to do your own dependency analysis and renamer, but the instance part isn’t clear to me. Oh, and you also have to write your own kind inference for data type declarations. Who knew implementing a Haskell was so involved? So beware future travelers… THIH is awesome, but these are the things I’ve found missing. Ciao!

2 4

ANNOUNCE: graphviz 2999.19.0.0
by Ivan Lazar Miljenovic 03 May '17

03 May '17

I've just released a new version of my Haskell bindings to the Graphviz graph visualisation toolkit. Note that the major version bump is solely because I had to remove what I thought was a useful feature (trying to allow you to do things like `"a" --> ["b", "c", "d"]` in Monadic graphs by automagically converting the "a" into ["a"]) turned out not to work in practice (as people will typically use this with literal values, but when combined with OverloadedStrings results in GHC getting confused as to what the type is). So unless you actually managed to use this functionality, then the API remains the same as 2999.18.* and you should just be able to bump your upper versions in your .cabal files (which you all do, right)? -- Ivan Lazar Miljenovic Ivan.Miljenovic(a)gmail.com http://IvanMiljenovic.wordpress.com

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Cabal and IPv6
by Serguey Zefirov 02 May '17

02 May '17

I have found that Cabal does not work on IPv6-only networks (which my machine happen to be part of). The problem is basically this: "ping hackage.haskell.org" does not resolve host while "ping6 hackage.haskell.org" does. Thus cabal cannot do anything useful on that machine. Do anyone have a solution for that? I was unable to find any on the internet. ;)

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Final call for papers: Trends in Functional Programming, 19-21 june 2017, University of Kent, Canterbury
by Peter Achten 01 May '17

01 May '17

----------------------------- F I N A L C A L L F O R P A P E R S ----------------------------- ======== TFP 2017 =========== 18th Symposium on Trends in Functional Programming 19-21 June, 2017 University of Kent, Canterbury https://www.cs.kent.ac.uk/events/tfp17/index.html The symposium on Trends in Functional Programming (TFP) is an international forum for researchers with interests in all aspects of functional programming, taking a broad view of current and future trends in the area. It aspires to be a lively environment for presenting the latest research results, and other contributions (see below). Authors of draft papers will be invited to submit revised papers based on the feedback receive at the symposium. A post-symposium refereeing process will then select a subset of these articles for formal publication. TFP 2017 will be the main event of a pair of functional programming events. TFP 2017 will be accompanied by the International Workshop on Trends in Functional Programming in Education (TFPIE), which will take place on 22 June. The TFP symposium is the heir of the successful series of Scottish Functional Programming Workshops. Previous TFP symposia were held in * Edinburgh (Scotland) in 2003; * Munich (Germany) in 2004; * Tallinn (Estonia) in 2005; * Nottingham (UK) in 2006; * New York (USA) in 2007; * Nijmegen (The Netherlands) in 2008; * Komarno (Slovakia) in 2009; * Oklahoma (USA) in 2010; * Madrid (Spain) in 2011; * St. Andrews (UK) in 2012; * Provo (Utah, USA) in 2013; * Soesterberg (The Netherlands) in 2014; * Inria Sophia-Antipolis (France) in 2015; * and Maryland (USA) in 2016. For further general information about TFP please see the TFP homepage. (http://www.tifp.org/) == SCOPE == The symposium recognizes that new trends may arise through various routes. As part of the Symposium's focus on trends we therefore identify the following five article categories. High-quality articles are solicited in any of these categories: Research Articles: leading-edge, previously unpublished research work Position Articles: on what new trends should or should not be Project Articles: descriptions of recently started new projects Evaluation Articles: what lessons can be drawn from a finished project Overview Articles: summarizing work with respect to a trendy subject Articles must be original and not simultaneously submitted for publication to any other forum. They may consider any aspect of functional programming: theoretical, implementation-oriented, or experience-oriented. Applications of functional programming techniques to other languages are also within the scope of the symposium. Topics suitable for the symposium include, but are not limited to: Functional programming and multicore/manycore computing Functional programming in the cloud High performance functional computing Extra-functional (behavioural) properties of functional programs Dependently typed functional programming Validation and verification of functional programs Debugging and profiling for functional languages Functional programming in different application areas: security, mobility, telecommunications applications, embedded systems, global computing, grids, etc. Interoperability with imperative programming languages Novel memory management techniques Program analysis and transformation techniques Empirical performance studies Abstract/virtual machines and compilers for functional languages (Embedded) domain specific languages New implementation strategies Any new emerging trend in the functional programming area If you are in doubt on whether your article is within the scope of TFP, please contact the TFP 2017 program chairs, Scott Owens and Meng Wang. == BEST PAPER AWARDS == To reward excellent contributions, TFP awards a prize for the best paper accepted for the formal proceedings. TFP traditionally pays special attention to research students, acknowledging that students are almost by definition part of new subject trends. A student paper is one for which the authors state that the paper is mainly the work of students, the students are listed as first authors, and a student would present the paper. A prize for the best student paper is awarded each year. In both cases, it is the PC of TFP that awards the prize. In case the best paper happens to be a student paper, that paper will then receive both prizes. == PAPER SUBMISSIONS == Acceptance of articles for presentation at the symposium is based on a lightweight peer review process of extended abstracts (4 to 10 pages in length) or full papers (20 pages). The submission must clearly indicate which category it belongs to: research, position, project, evaluation, or overview paper. It should also indicate which authors are research students, and whether the main author(s) are students. A draft paper for which ALL authors are students will receive additional feedback by one of the PC members shortly after the symposium has taken place. We use EasyChair for the refereeing process. Papers must be submitted at: https://easychair.org/conferences/?conf=tfp17 Papers must be written in English, and written using the LNCS style. For more information about formatting please consult the Springer LNCS web site: http://www.springer.com/computer/lncs?SGWID=0-164-6-793341-0 == INVITED SPEAKERS == Conor McBride University of Strathclyde (UK) Cătălin Hriţcu INRIA Paris (FR) == IMPORTANT DATES == Submission of draft papers: 5 May, 2017 Notification: 12 May, 2017 Registration: 11 June, 2017 TFP Symposium: 19-21 June, 2017 Student papers feedback: 29 June, 2017 Submission for formal review: 2 August, 2017 Notification of acceptance: 3 November, 2017 Camera ready paper: 2 December, 2017 == PROGRAM COMMITTEE == Co-Chairs Meng Wang University of Kent (UK) Scott Owens University of Kent (UK) PC Jeremy Yallop University of Cambridge (UK) Nicolas Wu University of Bristol (UK) Laura Castro University of A Coruña (ES) Gabriel Scherer Northeastern University (US) Edwin Brady University of St Andrews (UK) Janis Voigtländer Radboud University Nijmegen (NL) Peter Achten Radboud University Nijmegen (NL) Tom Schrijvers KU Leuven (BE) Matthew Fluet Rochester Institute of Technology (US) Mauro Jaskelioff CIFASIS/Universidad Nacional de Rosario (AG) Patricia Johann Appalachian State University (US) Bruno Oliveira The University of Hong Kong (HK) Rita Loogen Philipps-Universität Marburg (GE) David Van Horn University of Marylan (US) Soichiro Hidaka Hosei University (JP) Michał Pałka Chalmers University of Technology (SE) Sandrine Blazy University of Rennes 1 - IRISA (FR)

1 0

hash map/associative structure
by Ketil Malde 30 Apr '17

30 Apr '17

Hi, I've been using Judy arrays as a fast and even more importatnly, compact associative structure. Infortunately, I'm getting occasional segfaults, and I'm unable to find anything wrong with my code. Others also report something similar. The Debian maintainer of libjudy made a version without some dubious optimizations, but that didn't help...at least not substantially. So the question is, what is a good replacement? I just need Word64 -> Integral, but again, I expect to fill all of main memory with data, so memory compactness is important. Anything using trees and boxed values (e.g. Data.IntMap and friends) out. I only need to be able to insert, modify (add one), and finally extract the key-value pairs (e.g. 'elems'). Any suggestions? -k -- If I haven't seen further, it is by standing in the footprints of giants

2 1

How can I find out which functions can be run on an expression?
by Julian Leviston 30 Apr '17

30 Apr '17

I'd like to programmatically find out which functions in a module could possibly apply to a particular expression. I also posted this to stack overflow. To make this concrete: {-# LANGUAGE TemplateHaskell #-} module Test where -- we'll import template-haskell from Lens -- so we can create prisms automatically for our 'AST' import qualified Control.Lens.TH as LTH --- some 'AST' in a toy language data CExp = CLit Int -- a literal integer | CAdd CExp CExp -- addition | CMul CExp CExp -- multiplication | CSub CExp CExp -- subtraction deriving Show -- an eval for our AST eval :: CExp -> Int eval exp = case exp of CLit i -> i CAdd e1 e2 -> eval e1 + eval e2 CMul e1 e2 -> eval e1 * eval e2 CSub e1 e2 -> eval e1 - eval e2 -- a function to build a sum using add with our AST, from a list of Int values listToSums :: [Int] -> CExp listToSums = foldr CAdd (CLit 0) . fmap CLit -- here we make prisms for looking at particular values -- in the CExp AST LTH.makePrisms ''CExp -- let's have an expression: theList1 :: CExp theList1 = listToSums [1..38] Now, at this point, I'd like a function that can give me a list of all the top level functions of a particular module (including this one) that are able to be applied to the expression theList1. This will include the prisms that were created with makePrisms. It would be fine if it uses the hint library's Interpreter monad. I've been experimenting with it a bit, and while I can get a list of all of the definitions at the top level of any module, and I can find the types of them, too (more or less), I'm a bit lost about how to pass an expression in as an argument to these functions then check if that exprssions will typecheck. If I can do that, I can run filter across all of the functions in a module, which lets me find out which ones are applicable. Many thanks in advance.

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State of Haskell IDE Engine
by Alan & Kim Zimmerman 30 Apr '17

30 Apr '17

Some of you have been wondering what has happened to the haskell-ide-engine[1], and whether it may perhaps have died. Development has resumed, based mainly on the existence of an enabling technology in the Language Server Protocol[2] which is starting to have implementations for IDEs and Languages[3]. It was always the intention to leverage off common infrastructure at the IDE side, and this protocol is making that possible. The current state for haskell-ide-engine is that support is provided in master[4], which has been tested in emacs using[5] (and [6] until the branch is merged). It is also tested against vscode[7] using the vscode-hie-server plugin[8]. Current features include - diagnostics provided via hlint and ghc-mod (using flycheck in emacs) - hover support giving the type under the cursor - ability to apply hlint suggestions as codeActions, via apply-refact - HaRe refactorings exposed in the emacs version. The vscode plugin lags in this, my skills are limited There is a lot of development happening on the emacs lsp-mode, as it benefits many languages, not just haskell, and so developers from other languages are also contributing. The LSP support for haskell-ide-engine is supplied by a separate library[9] which is being used in at least 3 other LSP servers to my knowledge. These will be made public when/if it suits their creators to do so. The general plan going forward is to focus HIE on being an LSP server. Other transports will not be removed, but the driving paradigm will be LSP support. The longer term plan is to use this as a platform to drive more interactivity back into GHC, starting with exploring incremental parsing driven by the document change notifications provided in the LSP protocol, and supported in haskell-lsp[9]. Alan [1] https://github.com/haskell/haskell-ide-engine/issues/218 [2] https://github.com/Microsoft/language-server-protocol [3] https://github.com/Microsoft/language-server-protocol/wiki/Protocol-Impleme… [4] https://github.com/haskell/haskell-ide-engine [5] https://github.com/alanz/lsp-haskell [6] https://github.com/alanz/lsp-mode/tree/project-ask [7] http://code.visualstudio.com/ [8] https://github.com/alanz/vscode-hie-server [9] https://github.com/alanz/haskell-lsp

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Deadline Extension: International Workshop on OCL and Textual Modeling (OCL 2017)
by Achim D. Brucker 29 Apr '17

29 Apr '17

(Apologies for duplicates) New Deadline: May 7, 2017 CALL FOR PAPERS 17th International Workshop on OCL and Textual Modeling Co-located with STAF 2017 SOFTWARE TECHNOLOGIES: APPLICATIONS AND FOUNDATIONS July 20, 2017, Marburg, Germany http://oclworkshop.github.io Modeling started out with UML and its precursors as a graphical notation. Such visual representations enable direct intuitive capturing of reality, but they have weaknesses: for example, detailed visual representations bear the risk of becoming overcrowded faster than textual models and some of the visual features lack the level of precision required to create complete and unambiguous specifications. These weaknesses of graphical notations encouraged the development of text-based modeling languages that either integrate with or replace graphical notations for modeling. Typical examples of such languages are OCL, textual MOF, Epsilon, and Alloy. Textual modeling languages have their roots in formal language paradigms like logic, programming and databases. The goal of this workshop is to create a forum where researchers and practitioners interested in building models using OCL or other kinds of textual languages can directly interact, report advances, share results, identify tools for language development, and discuss appropriate standards. In particular, the workshop will encourage discussions for achieving synergy from different modeling language concepts and modeling language use. The close interaction will enable researchers and practitioners to identify common interests and options for potential cooperation. ## Topics of interest Topics of interest include (but are not limited to): - Mappings between textual modeling languages and other languages/formalisms - Algorithms, evaluation strategies and optimizations in the context of textual modeling languages for: - validation, verification, and testing, - model transformation and code generation, - meta-modeling and DSLs, and - query and constraint specifications - Alternative graphical/textual notations for textual modeling languages - Evolution, transformation and simplification of textual modeling expressions - Libraries, templates and patterns for textual modeling languages - Tools that support textual modeling languages (e.g., verification of OCL formulae, runtime monitoring of invariants) - Complexity results for textual modeling languages - Quality models and benchmarks for comparing and evaluating textual modeling tools and algorithms - Successful applications of textual modeling languages - Case studies on industrial applications of textual modeling languages - Experience reports: - usage of textual modeling languages and tools in complex domains, - usability of textual modeling languages and tools for end-users - Empirical studies about the benefits and drawbacks of textual modeling languages - Innovative textual modeling tools - Comparison, evaluation and integration of modeling languages - Correlation between modeling languages and modeling tasks This year, we particularly encourage submissions describing applications and case studies of textual modeling as well as test suites and benchmark collections for evaluating textual modeling tools. ## Venue This workshop will be organized as a part of STAF 2017 Conferenze in Marburg, Germany. It was previously organized as part of the MODELS conference. Similar to its predecessors , the workshop addresses both people from academia and industry . The aim is to provide a forum for addressing integration of OCL and other textual modeling languages , as well as tools for textual modeling , and for disseminating good practice and discussing the new requirements for textual modeling . ## Workshop Format The workshop will include short (about 15 min) presentations, parallel sessions of working groups, and sum-up discussions. ## Submissions Two types of papers will be considered: * Short contributions (between 6 and 8 pages) describing new ideas, innovative tools or position papers. * Full papers (between 12 and 16 pages). in LNCS format. Submissions should be uploaded to [EasyChair](https://easychair.org/conferences/?conf=ocl2017). The program committee will review the submissions (minimum 2 reviews per paper, usually 3 reviews) and select papers according to their relevance and interest for discussions that will take place at the workshop. Accepted papers will be published online in a post-conference edition of [CEUR](http://www.ceur-ws.org). ## Important Dates - Submission of papers: May 7, 2017 (extended) - Notification: May 25, 2017 - Workshop date: July 20, 2017 -- Dr. Achim D. Brucker | Software Assurance & Security | University of Sheffield https://www.brucker.ch | https://logicalhacking.com/blog @adbrucker | @logicalhacking

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th-abstraction: A new library for inspecting datatypes from Template Haskell
by Eric Mertens 28 Apr '17

28 Apr '17

Hello, I've uploaded a new library to Hackage that helps normalize the information one can get by reifying the type constructor of a type declared with data or newtype. https://hackage.haskell.org/package/th-abstraction https://github.com/glguy/th-abstraction I've found that I was duplicating a lot of code when trying to maintain compatibility across a range of Template Haskell versions when using the 'reify' operation. Currently I'm testing against GHC versions as old as 7.4.2 and as new as 8.2.1-rc1. This package eliminates some of the noise that comes from reify's syntax-oriented constructors and eliminates the differences across normal and GADT syntax. I expect to add more Template Haskell functionality to this package over time as needed with a focus on being able to maintain compatibility across a wide range of template-haskell package versions. I hope others are able to find it useful! Best regards, Eric Mertens "glguy"

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ANN: wxHaskell 0.92.3.0
by Henk-Jan van Tuyl 28 Apr '17

28 Apr '17

L.S., I am happy to announce a new version of wxHaskell: 0.92.3.0 Windows users can still use wxInstall Achelanne 0.1 to install this new version of wxHaskell.[0][1] Changes in wxHaskell since 0.92.2: - Improvements for compilation on BSD platform - Improved commandline handling - Sample program PaintGC.hs added - Compilation can now be done with an alternative wx-config.exe - Simplification of Windows build process with Stack - Several bugs solved Thanks to everyone who contributed! What is wxHaskell? ------------------ wxHaskell[2] is a portable and native GUI library for Haskell. The goal of the project is to provide an industrial strength GUI library for Haskell, but without the burden of developing (and maintaining) one ourselves. wxHaskell is therefore built on top of wxWidgets[3] – a comprehensive C++ library that is portable across all major GUI platforms; including GTK, Windows, X11, and MacOS X. Furthermore, it is a mature library (in development since 1992) that supports a wide range of widgets with the native look-and-feel. Links ----- See the homepage of wxHaskell for more information: https://wiki.haskell.org/WxHaskell Repository: https://github.com/wxHaskell/wxHaskell Tickets: https://sourceforge.net/p/wxhaskell/_list/tickets The packages are: - wxc https://hackage.haskell.org/package/wxc - wxdirect https://hackage.haskell.org/package/wxdirect - wxcore https://hackage.haskell.org/package/wxcore - wx https://hackage.haskell.org/package/wx Regards, Henk-Jan van Tuyl [0] http://sourceforge.net/projects/wxhaskell/files/wxInstall/ [1] https://wiki.haskell.org/WxHaskell/Windows#Installing_the_easy_way [2] https://wiki.haskell.org/WxHaskell [3] https://wxwidgets.org/ -- 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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bounty for vty on Windows
by Simon Michael 28 Apr '17

28 Apr '17

Hi all, vty is a nice full-screen curses-style API, and the basis for the nice higher-level brick TUI (text UI) framework, that builds on POSIX platforms only. All agree that it would be nice to make it work on Windows too. This would allow building cross-platform TUIs with haskell. Also there are things in vty, such as the Graphics.Vty.Attributes, that would be useful for CLIs too. I summarised current status and have kicked off a bounty towards getting Windows support added to the vty lib. I'm sending this to raise interest and invite your help, be you a person with a Windows machine, a potential bounty donor, or someone interested in improving Haskell's portability and applicability. https://github.com/jtdaugherty/vty/pull/1#issuecomment-297143444 <https://github.com/jtdaugherty/vty/pull/1#issuecomment-297143444> My particular interest is in making hledger-ui[1] cross platform, and in being able to use vty's higher-level terminal styles in CLI tools on all platforms. Best! Simon [1] http://hledger.org/hledger-ui.html <http://hledger.org/hledger-ui.html>

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Should I report a bug on GHC 7.10.3, or is it past it's end-of-life?
by Ramin Honary 28 Apr '17

28 Apr '17

I'm getting an "internal error: evacuate: strange closure type" in GHC 7.10.3. Should I report it? Would it even do any good? It doesn't seem there is any more development on the 7.10 branch anymore. If it is still being developed, should I try updating my GHC to a more recent build of 7.10.3? Looking at the core dump file, it appears to be a problem in the garbage collector. I've done a bit of work trying get around the bug, including using -dcore-lint and -O0, and updating my dependency libraries, and I can still reproduce the issue very regularly in my own environment by calling a single method in my code base, either in GHCi or in a compiled binary test program.

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Trends in Functional Programming in Education TFPIE 2017, Canterbury 22 June, SECOND CALL FOR PAPERS
by Simon Thompson 28 Apr '17

28 Apr '17

TFPIE 2017 Trends in Functional Programming in Education, 2017 https://www.cs.kent.ac.uk/people/staff/sjt/TFPIE2017/ The sixth workshop on Trends in Functional Programming in Education, 2017, which is to be held on the Canterbury campus of the University of Kent on Thursday, 22 June, following the 2017 TFP meeting on 19–21 June. TFPIE workshops have previously been held in St Andrews, Scotland (2012), Provo Utah, USA (2013), Soesterberg, The Netherlands (2014), and Sophia-Antipolis, France (2015), College Park, USA (2016). A particular topic of this year's TFPIE will be MOOCs and other online learning, and as well as a session on this, we're looking forward to announcing a keynote speaker in this area very soon. The goal of TFPIE is to gather researchers, teachers and professionals that use, or are interested in the use of, functional programming in education. TFPIE aims to be a venue where novel ideas, classroom-tested ideas and work-in-progress on the use of functional programming in education are discussed. The one-day workshop will foster a spirit of open discussion by having a review process for publication after the workshop. The program chair of TFPIE 2017 will screen submissions to ensure that all presentations are within scope and are of interest to participants. After the workshop, presenters will be invited to submit revised versions of their articles for publication in the journal Electronic Proceedings in Theoretical Computer Science (EPTCS). Second call for papers TFPIE 2017 welcomes submissions describing techniques used in the classroom, tools used in and/or developed for the classroom and any creative use of functional programming (FP) to aid education in or outside Computer Science. Topics of interest include, but are not limited to: - FP and beginning CS students - FP and Computational Thinking - FP and Artificial Intelligence - FP in Robotics - FP and Music - Advanced FP for undergraduates - FP in graduate education - Engaging students in research using FP - FP in Programming Languages - FP in the high school curriculum - FP as a stepping stone to other CS topics - FP and Philosophy - The pedagogy of teaching FP - FP and e-learning: MOOCs, automated assessment etc. - Best Lectures – more details below In addition to papers, we are requesting best lecture presentations. What’s your best lecture topic in an FP related course? Do you have a fun way to present FP concepts to novices or perhaps an especially interesting presentation of a difficult topic? In either case, please consider sharing it. Best lecture topics will be selected for presentation based on a short abstract describing the lecture and its interest to TFPIE attendees. Submission Potential presenters are invited to submit an extended abstract (4-6 pages) or a draft paper (up to 16 pages) in EPTCS style. The authors of accepted presentations will have their preprints and their slides made available on the workshop's website. Papers and abstracts can be submitted via easychair at the following link: https://easychair.org/conferences/?conf=tfpie2017 After the workshop, presenters will be invited to submit (a revised version of) their article for review. The PC will select the best articles for publication in the journal Electronic Proceedings in Theoretical Computer Science (EPTCS). Articles rejected for presentation and extended abstracts will not be formally reviewed by the PC. Programme committee Dr Laura Castro, University of A Coruña Prof Ralf Lämmel, University of Koblenz-Landau Dr Elena Machkasova, University of Minnesota, Morris Prof Michel Mauny, Inria, Paris Dr Jeremy Singer, University of Glasgow Prof Simon Thompson, University of Kent (chair) Important dates Submissions of draft papers: 10 May, 2017 Notification: 17 May, 2017 Registration: 11 June, 2017 Workshop: 22 June 2017 Submission for formal review: 18 August, 2017 Notification of acceptance: 6 October, 2017 Camera ready paper: 3 November, 2017 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

1 0

Looking for maintainers or comaintainers on my Haskell projects
by Christopher Done 28 Apr '17

28 Apr '17

Hi all, The short version is: I’ve been battling RSI in my fingers for some years. I’m doing various things to mitigate that problem, but I have very limited finger bandwidth these days; enough to work at my usual pace at my job, but not much in the evenings and weekends, and so I can’t manage to do much on my hobby projects. I’m also not as motivated these days to work on my set of open source projects, and am turning my attention to different things. It’s not great, but that’s life. I don’t think that the users of my packages are getting the best maintainership deal. Rather than be “the absentee maintainer”, I’d prefer a straight-forward transition of maintainership or ownership to someone who can put the right energy and time in. In terms of packages, there are really two that have a significant maintenance burden and users aren’t being served very well: - HIndent <https://github.com/chrisdone/hindent> has a significant amount of issues opened for it regularly, and many of them require discussion and debate. If someone would like to become a co-maintainer, let me know. It may (eventually) make sense to move it to a more general GitHub organization like commercialhaskell or haskell. - Intero <https://github.com/commercialhaskell/intero/issues>, which seems to have been a success, has a pretty big maintenance burden on “this doesn’t work” kind of issues which require investigation. There’s some Emacs Lisp work to do on it, and some Haskell work on the intero binary, and a whole lot of platform-specific problems or tooling not working together. On the other hand people really like this project, and there’s a lot of tooling potential. If you want to take xeno <https://github.com/chrisdone/xeno> and make it into a publishable package, please do so. The rest of my projects that are on Stackage are: labels <https://hackage.haskell.org/package/labels>, ace <https://hackage.haskell.org/package/ace>, ical <https://hackage.haskell.org/package/ical>, check-email <https://hackage.haskell.org/package/check-email>, freenect <https://hackage.haskell.org/package/freenect>, frisby <https://hackage.haskell.org/package/frisby>, gd <https://hackage.haskell.org/package/gd>, ini <https://hackage.haskell.org/package/ini>, lucid <https://hackage.haskell.org/package/lucid>, osdkeys <https://hackage.haskell.org/package/osdkeys>, pdfinfo <https://hackage.haskell.org/package/pdfinfo>, present <https://hackage.haskell.org/package/present>, pure-io <https://hackage.haskell.org/package/pure-io>, scrobble <https://hackage.haskell.org/package/scrobble>, shell-conduit <https://hackage.haskell.org/package/shell-conduit>, sourcemap <https://hackage.haskell.org/package/sourcemap>, descriptive <https://hackage.haskell.org/package/descriptive>, wrap <https://hackage.haskell.org/package/wrap>, path <https://hackage.haskell.org/package/path>, weigh <https://hackage.haskell.org/package/weigh>, haskell-docs <https://hackage.haskell.org/package/haskell-docs>, and structured-haskell-mode <https://hackage.haskell.org/package/structured-haskell-mode>. If you’re interested in taking over or co-maintaining any of them, let me know. Some are interesting, others are boring, some are trivial. I have other packages on Hackage, but they’re mostly dead or experiments that don’t need maintenance anyway. I’ve started the process of adding or changing maintainers on my public services: - Haskell News <https://github.com/haskellnews> is now a GitHub organization. Luke Murphy is a co-owner, and has full access to the DigitalOcean account that is running the service. So if you want to work on that project, I’m not in the way. - lpaste <https://github.com/lpaste/lpaste> has been moved to its own DigitalOcean account too. If anyone is interested in taking over the project or co-running it, let me know. - tryhaskell <https://github.com/chrisdone/tryhaskell> doesn’t really require any maintenance, but it’s also on its own DigitalOcean account now too. - IRCBrowse <https://github.com/chrisdone/ircbrowse> is now on its own DigitalOcean account too. It requires maintenance once in a while. If anyone is interested in taking over the project or co-running it, let me know. Cheers!

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Re: [Haskell-cafe] Partial type family application
by Oleg 27 Apr '17

27 Apr '17

If the goal is to write higher-order type families, we can do that already -- and were able to do for a long time. For example, please see http://okmij.org/ftp/Haskell/TTypeable/TTypeable.hs that was written in 2012 for http://okmij.org/ftp/Haskell/typeEQ.html It shows the type-level function that checks for a membership in a type-level using the equality function supplied by a user as the first argument. Incidentally, here is the definition type instance Member f x NIL = HFalse type instance Member f x (h :/ t) = ORELSE (Apply f (x,h)) (CLOS AC_Member (f,x,t)) It was written before the modern syntax for type-level lists and booleans. This is an example of the general technique of defunctionalization.

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[JOB] Summer contracting opportunity for CodeWorld
by Chris Smith 27 Apr '17

27 Apr '17

Hello, Haskellers. I'm happy to announce a summer contracting opportunity helping to create documentation and educational materials for the CodeWorld project. CodeWorld (https://code.world) is a platform (and soon, a curriculum) for teaching mathematics via Haskell programming to children at the U.S. middle school level (ages 11-14). For more information about the CodeWorld project and its motivations, I can refer you to my recent BayHac presentation at https://youtu.be/7CGuI9HcfqQ Start: Early June End: Mid-August (but flexible) Full-time commitment Anticipated compensation: US$1500 / week Working remotely is expected, with the possibility of one week of required travel. As part of this position, you will work closely as a team with two other full-time writers to create detailed educational materials for use with the CodeWorld platform. You will be the team's expert on computer programming and the Haskell programming language. Other team members have expertise in mathematics education, and general and special needs education. The team's over-arching goal will be to produce objectives, instructional video scripts, visual aids, reference documentation (online and offline), pencil-and-paper activities, classroom activity planning, assessments, and any other resources necessary to support the success of this curriculum as a year-long class in schools. You should expect a typical day to include writing, editing and reviewing the content of others, planning objectives and content sequence, brainstorming activities and resources to help with content units, and some debate and consensus-building with the team on important design decisions. All artifacts produced during the job will be released under open source and/or Creative Commons licenses, suitable for use without charge by schools and organizations around the world. Qualifications: - Strong knowledge of Haskell programming language fundamentals. - Excellent writing and communication skills (in English), and in particular, an ability to explain technical ideas to an audience of beginners in a compelling way. - A mathematics and/or education background would be beneficial, but is not required. For this position, you will be a contractor for the New York Haskell User Group. Resumes can be sent to cdsmith(a)gmail.com.

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complex multiplication function in Haskell
by Mahmoud Murad 27 Apr '17

27 Apr '17

Hi there, The number 354162 has 6 digits and contains all digits from 1 to 6, and it can be considered as a multiplication of 3 * 54 = 162. so what I need is a function that will take all the real number and return the number that can be split as above, 354162 .. 3 * 54 = 162 I have no idea how to do such a thing! any help!

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Getting ready for Summer of Haskell 2017
by Niki Vazou 25 Apr '17

25 Apr '17

We are happy to announce that Summer of Haskell 2017 will host at least 8 students, funded from the Haskell community and corporate sponsors. You can find all information (including the timeline) at the Summer of Haskell new webpage: https://summer.haskell.org/ Students can submit applications from April 25th until the May 6th. We recommend that interested students start thinking about their proposals and brainstorm with potential mentors. In case you would like to participate as a student, but you have no idea what to work on, we have a page dedicated to ideas here: https://summer.haskell.org/ideas.html Teachers of FP courses at universities around the world are strongly encouraged to share this announcement with their students. Mentors, as well as everyone from the community, are encouraged to contribute ideas by sending pull requests to the Summer of Haskell repository (or contacting us): https://github.com/haskell-org/summer-of-haskell Sponsors are still welcome, as we can add more slots if the necessary funds become available. Combining our current individual donations with partial sponsors, we only need $2000 more to fund an additional student. Please consider making a small donation towards that goal. If you would like to contribute do not hesitate to contact us or donate directly: https://wiki.haskell.org/Donate_to_Haskell.org We’d like to thank our current sponsors for making this Summer of Haskell possible: haskell.org kicked things off this year by funding a student and organizing the Summer of Haskell 2017 after a successful Summer of Haskell 2016 <https://mail.haskell.org/pipermail/haskell-cafe/2016-December/125702.html>. Asahi Net <http://asahinet.com/> is a Japanese Internet service provider that has been running stable systems for over 25 years. They are a proud sponsor of the Summer of Haskell, and contribute to the Japanese Haskell community. Awake Networks <http://www.awakenetworks.com/> is building a next generation network security and analytics platform. They are a proud sponsor of the Summer of Haskell and contribute broadly to the Haskell community. CodeWorld <http://code.world/> is an educational project that blends mathematics and Haskell programming into a visual playground. Chris Smith has volunteered to fund two students to work on CodeWorld in particular. Facebook <http://facebook.com/> uses Haskell in its anti-abuse infrastructure <https://code.facebook.com/posts/745068642270222/fighting-spam-with-haskell/>, and as part of that effort we open-sourced the Haxl <https://github.com/facebook/Haxl> framework which is being used at scale in production to automatically parallelise data-fetching code. We're delighted to be able to support the Haskell community's efforts by sponsoring a student for this year's Summer of Haskell. Fugue Inc. <http://fugue.co/> radically simplifies cloud operations with its software-defined system for dynamically orchestrating and enforcing cloud infrastructure at scale. Fugue uses Haskell in its product and is proud to sponsor a student to improve the ecosystem. Galois <http://galois.com/> applies cutting-edge computer science and applied mathematics to solve difficult technological problems, delivering practical solutions tailored to our clients’ needs. Haskell and other functional programming languages are key tools we use in providing these solutions. Tweag I/O <http://tweag.io/> is a network of software innovation labs across Europe. We develop novel solutions and products for our clients around the world. Haskell is key to delivering fast, correct and maintainable code. We have shipped Haskell in anything from tiny web services to large high-performance compute clusters with custom hardware. We're particularly keen to help the community grow Haskell into the strongest systems programming language and ecosystem out there. We're very proud to sponsor a student this summer to help make it happen. Finally, Davean has volunteered to fund a student expressly to work on the Hadrian build system for GHC <https://haskell-org.github.io/summer-of-haskell/ideas.html#hadrian-ghc>. Feel free to contact us at (nvazou at cs.umd.edu and m at jaspervdj.be) if want to help or if you have any ideas, questions, or concerns. Best, Niki Vazou & Jasper Van der Jeugt for the Haskell.org Committee

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Senior Lectureships in Computer Science at Chalmers and Gothenburg U
by Andreas Abel 25 Apr '17

25 Apr '17

We are hiring full-time permanent lecturers! http://www.chalmers.se/en/about-chalmers/vacancies/Pages/default.aspx?rmpag… http://www.gu.se/english/about_the_university/job-opportunities/vacancies-d… The positions are focusing on teaching, but some time will be available for research as well. Excerpt from the description: Major responsibilities The scientific area is Computer Science, interpreted broadly. The position is a full-time tenured appointment with focus on education and pedagogical development. You will teach a variety of topics in Computer Science; there may include courses such as programming, data structures, algorithms and databases. You will also supervise bachelor level projects and master’s theses. Besides teaching, you will keep up with the technical and pedagogical development in the areas of the position and introduce new methods in the curriculum. As a faculty member you will share the responsibility of the administration and management of the department and the educational programmes. You will collaborate with industrial, academic or governmental partners, and take part in the research conducted at the department. In addition, you are encouraged to apply for funding of further pedagogical advancement of our programmes, and for research funding. -- Andreas Abel <>< Du bist der geliebte Mensch. Department of Computer Science and Engineering Chalmers and Gothenburg University, Sweden andreas.abel(a)gu.se http://www.cse.chalmers.se/~abela/

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Munich Haskell Meeting, 2017-01-26 @ 19:30
by Christian Neukirchen 25 Apr '17

25 Apr '17

Dear all, This week, our monthly Munich Haskell Meeting will take place again on Thursday, April 27 at Augustiner-Gaststätte Rumpler (Baumstraße 21) at 19h30. For details see here: http://muenchen.haskell.bayern/dates.html If you plan to join, please add yourself to this dudle so we can reserve enough seats! It is OK to add yourself to the dudle anonymously or pseudonymously. https://dudle.inf.tu-dresden.de/haskell-munich-apr-2017/ Everybody is welcome! cu, -- Christian Neukirchen <chneukirchen(a)gmail.com> http://chneukirchen.org

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VSTTE 2017 - Deadline Extension
by Andrei Paskevich 25 Apr '17

25 Apr '17

*** DEADLINE EXTENSION *** 9th Working Conference on Verified Software: Theories, Tools, and Experiments (VSTTE) https://vstte17.lri.fr July 22-23, 2017, Heidelberg, Germany Co-located with the 29th International Conference on Computer-Aided Verification, CAV 2017 Deadline Extension The deadlines for submitting abstracts and full papers have been extended by one week. The new deadlines are firm. Important Dates * Abstract submission (extended): Mon, May 1, 2017 (AoE) * Full paper submission (extended): Mon, May 8, 2017 (AoE) * Notification: Mon, Jun 5, 2017 * VSTTE: Sat-Sun, Jul 22-23, 2017 * Camera-ready: Mon, Aug 21, 2017 Overview The goal of the VSTTE conference series is to advance the state of the art in the science and technology of software verification, through the interaction of theory development, tool evolution, and experimental validation. We welcome submissions describing significant advances in the production of verified software, i.e., software that has been proved to meet its functional specifications. Submissions of theoretical, practical, and experimental contributions are equally encouraged, including those that focus on specific problems or problem domains. We are especially interested in submissions describing large-scale verification efforts that involve collaboration, theory unification, tool integration, and formalized domain knowledge. We also welcome papers describing novel experiments and case studies evaluating verification techniques and technologies. Topics of interest for VSTTE include education, requirements modeling, specification languages, specification/verification/certification case studies, formal calculi, software design methods, automatic code generation, refinement methodologies, compositional analysis, verification tools (e.g., static analysis, dynamic analysis, model checking, theorem proving, satisfiability), tool integration, benchmarks, challenge problems, and integrated verification environments. Paper Submissions We accept both long (limited to 16 pages, references not included) and short (limited to 10 pages, references not included) paper submissions. Short submissions also cover Verification Pearls describing an elegant proof or proof technique. Submitted research papers and system descriptions must be original and not submitted for publication elsewhere. Each submission will be evaluated by at least three members of the Program Committee. We expect that one author of every accepted paper will present their work at the conference. Paper submissions must be written in English using the LNCS LaTeX format (http://www.springer.com/gp/computer-science/lncs/conference-proceedings-gui…) and must include a cogent and self-contained description of the ideas, methods, results, and comparison to existing work. Papers will be submitted via EasyChair at the VSTTE 2017 conference page (https://www.easychair.org/conferences/?conf=vstte2017) The post-conference proceedings of VSTTE 2017 will be published in the LNCS series. Authors of accepted papers will be requested to sign the copyright transfer form. A selection of best papers will be invited for publication in the Journal of Automated Reasoning. Invited Speakers * Christoph Weidenbach (Max Planck Institute for Informatics, Germany) * Santiago Zanella-Beguelin (Microsoft Research, UK) Program Chairs * Andrei Paskevich (Université Paris-Sud, France) * Thomas Wies (New York University, USA) Program Committee * June Andronick (University of New South Wales, Australia) * Christel Baier (TU Dresden, Germany) * Sandrine Blazy (Université de Rennes 1, France) * Arthur Charguéraud (Inria, France) * Ernie Cohen (Amazon Web Services, USA) * Rayna Dimitrova (MPI-SWS, Germany) * Carlo A. Furia (Chalmers University of Technology, Sweden) * Arie Gurfinkel (University of Waterloo, Canada) * Hossein Hojjat (Rochester Institute of Technology, USA) * Marieke Huisman (University of Twente, Netherlands) * Bart Jacobs (KU Leuven, Belgium) * Rajeev Joshi (NASA Jet Propulsion Laboratory, USA) * Zachary Kincaid (Princeton University, USA) * Akash Lal (Microsoft Research, India) * Shuvendu Lahiri (Microsoft Research, USA) * Francesco Logozzo (Facebook, USA) * Peter Müller (ETH Zürich, Switzerland) * Jorge A. Navas (SRI International, USA) * Scott Owens (University of Kent, UK) * Gerhard Schellhorn (Universität Augsburg, Germany) * Peter Schrammel (University of Sussex, UK) * Natarajan Shankar (SRI International, USA) * Mihaela Sighireanu (Université Paris-Diderot, France) * Julien Signoles (CEA LIST, France) * Michael Tautschnig (Queen Mary University of London, UK) * Tachio Terauchi (JAIST, Japan) * Oksana Tkachuk (NASA Ames Research Center, USA) * Mattias Ulbrich (Karlsruhe Institute of Technology, Germany)

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In search for an http/2 server
by Wojtek Narczyński 24 Apr '17

24 Apr '17

Honorable cafe, I'd like to experiment with http/2. The package wai used to contain Network.Wai.HTTP2, but the ChangeLog says it has been removed in 3.2.0, no further explanation given. Where should I look for an http/2 server these days? -- Kind regards, Wojtek Narczynski

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ANN: Compose Unconference and Exchange [NYC, May 20-21]
by Gershom B 24 Apr '17

24 Apr '17

I'm happy to announce that we now have a venue and dates for the affiliated Unconference and Exchange (aka "hackathon") for the Compose conference in NYC. It will take place the weekend immediately following the main conference, featuring improptu tutorials, collaborative coding, and generally be a good informal opportunity to work and discuss with functional programmers of all sorts. Registration (free) is at: https://www.eventbrite.com/e/cmpse-unconference-and-exchange-2017-tickets-3… Registration for the main conference remains at: https://composeconference.eventbrite.com. Early bird tickets are now gone, so get tickets while you can! We're also happy to announce the topic of our invited keynote by Emily Riehl: A Categorical View of Computational Effects * Unconference information: http://www.composeconference.org/2017/unconference/ * Unconference registration: https://www.eventbrite.com/e/cmpse-unconference-and-exchange-2017-tickets-3… * Full conference abstracts: http://www.composeconference.org/2017/program * Conference Registration: http://composeconference.eventbrite.com * Follow @composeconf on twitter for news: https://twitter.com/composeconf * On freenode irc, chat with fellow attendees at #composeconference * Corporate sponsorships are welcome. Current sponsors list forthcoming. * Policies (diversity and anti-harassment): http://www.composeconference.org/conduct * Email us with any questions at info(a)composeconference.org * Please forward this announcement to interested parties and lists.

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Fwd: 2nd Call for Papers: 16th ACM SIGPLAN Erlang Workshop 2017
by Rob Stewart 24 Apr '17

24 Apr '17

2nd CALL FOR PAPERS =============== Sixteenth ACM SIGPLAN Erlang Workshop http://erlang.org/workshop/2017/ ----------------------------------------------------------- Oxford, United Kingdom, 8 September 2017 Satellite event of the 22nd ACM SIGPLAN International Conference on Functional Programming (ICFP 2017) 3 - 9 September, 2017 The Erlang Workshop aims to bring together the open source, academic, and industrial communities of Erlang, to discuss technologies and languages related to Erlang. The Erlang model of concurrent programming has been widely emulated, for example by Akka in Scala, and even new programming languages were designed atop of the Erlang VM, such as Elixir. Therefore we would like to broaden the scope of the workshop to include systems like those mentioned above. The workshop will enable participants to familiarize themselves with recent developments on new techniques and tools, novel applications, draw lessons from users' experiences and identify research problems and common areas relevant to the practice of Erlang, Erlang-like languages, functional programming, distribution, concurrency etc. We invite three types of submissions. 1. Technical papers describing language extensions, critical discussions of the status quo, formal semantics of language constructs, program analysis and transformation, virtual machine extensions and compilation techniques, implementations and interfaces of Erlang in/with other languages, and new tools (profilers, tracers, debuggers, testing frameworks, etc.). The maximum length for technical papers is restricted to 12 pages. 2. Practice and application papers describing uses of Erlang in the "real-world", Erlang libraries for specific tasks, experiences from using Erlang in specific application domains, reusable programming idioms and elegant new ways of using Erlang to approach or solve a particular problem. The maximum length for the practice and application papers is restricted to 12 pages. Note that this is a maximum length; we welcome shorter papers also, and the program committee will evaluate all papers on an equal basis independent of their lengths. 3. Poster presentations describing topics related to the workshop goals. Each includes a maximum of 2 pages of the abstract and summary. Presentations in this category will be given an hour of shared simultaneous demonstration time. Workshop Co-Chairs ------------------ Scott Lystig Fritchie, VMware, USA Natalia Chechina, Glasgow University, UK Program Committee ----------------------------- (Note: the Workshop Co-Chairs are also committee members) Clara Benac Earle, Universidad Politecnica de Madrid, Spain Richard Carlsson, Klarna, Sweden Laura M. Castro, University of A Coruna, Spain Viktoria Fördős, Klarna, Sweden James S. Larson, Google, USA Important Dates ----------------------- Submission deadline: Fri May 26, 2017 Author notification: Fri June 23, 2017 Final submission for the publisher: Sat July 15, 2017 Workshop date: Fri September 8, 2017 Instructions to authors -------------------------------- Papers must be submitted online via EasyChair (via the "Erlang2017" event). The submission page is https://www.easychair.org/conferences/?conf=erlang2017 Submitted papers should be in portable document format (PDF), formatted using the ACM SIGPLAN style guidelines. Each submission must adhere to SIGPLAN's republication policy. Violation risks summary rejection of the offending submission. Accepted papers will be published by the ACM and will appear in the ACM Digital Library. The proceedings will be freely available for download from the ACM Digital Library from one week before the start of the conference until two weeks after the conference. Paper submissions will be considered for poster submission in the case they are not accepted as full papers. Venue & Registration Details ------------------------------------------ For registration, please see the ICFP 2017 web site at: http://icfp17.sigplan.org/ Related Links -------------------- ICFP 2017 web site: http://icfp17.sigplan.org/ Past ACM SIGPLAN Erlang workshops: http://www.erlang.org/workshop/ Open Source Erlang: http://www.erlang.org/ EasyChair submission site: https://www.easychair.org/conferences/?conf=erlang2017 Author Information for SIGPLAN Conferences: http://www.sigplan.org/authorInformation.htm Atendee Information for SIGPLAN Events: http://www.sigplan.org/Resources/Policies/CodeOfConduct/

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Looking for a new stackage curator
by Adam Bergmark 23 Apr '17

23 Apr '17

Hi everyone, We are looking to expand the stackage curator team again! Please see this document for more information: https://github.com/fpco/stackage/blob/master/become-a-curator.md If you are already convinced you can go straight to https://goo.gl/forms/eD6lTLtuyyHAIcfC2 Re-applications are encouraged! Cheers, Adam

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Dynamic Programming exercises
by Michael Litchard 22 Apr '17

22 Apr '17

I found the below link to be an illuminating read in regards to how to approach dynamic programming in haskell. Now I would like to test my understanding on different exercises. I'd like suggestions on problems that could be solved by the approach elucidated below. http://jelv.is/blog/Lazy-Dynamic-Programming/

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What does the "S" in "ShowS" signify?
by Chris Martin 21 Apr '17

21 Apr '17

The name "ShowS" in Text.Show always been mysterious to me. Can anyone explain why it's called that?

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