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QFPL is hiring 5 functional programmers
by David Laing 08 Mar '18

08 Mar '18

Hi all, QFPL is the Queensland Functional Programming Lab (QFPL) - where I work - and we have 5 positions open in Brisbane, Australia. We're part of Data61, the Australia federal organization that does research and engineering in the data science / ICT space. Our main focus in the lab is on doing things that make it easier for software engineers to use functional programming. This involves: - creating and running courses - improving libraries, documentation and tools - writing libraries and tools to fill gaps in the ecosystem All of the things we create are open-source. You can look at the job description / apply here: https://jobs.csiro.au/job/Brisbane%2C-QLD-EOI-Functional-Programming-Softwa… As far as I know, we're not currently hiring remote workers, but relocation support is a possibility. If you have questions about the lab or the role, I'm happy to answer them. Cheers, Dave

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1st call for papers: Trends in Functional Programming, 11-13 june 2018, Chalmers Campus Johanneberg, Gothenburg
by Peter Achten 07 Mar '18

07 Mar '18

----------------------------- C A L L F O R P A P E R S ----------------------------- ======== TFP 2018 =========== 19th Symposium on Trends in Functional Programming 11-13 June, 2018 Chalmers Campus Johanneberg, Gothenburg http://www.cse.chalmers.se/~myreen/tfp2018/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 at scope). Please be aware that TFP uses two distinct rounds of submissions (see below at submission details). TFP 2018 will be the main event of a pair of functional programming events. TFP 2018 will be accompanied by the International Workshop on Trends in Functional Programming in Education (TFPIE), which will take place on June 14. == 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 High-quality articles are solicited in any of these categories: Research Articles: Leading-edge, previously unpublished research work Position Articles: On what new trends should or should not be Project Articles: Descriptions of recently started new projects Evaluation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 2018 program chairs, Michał Pałka and Magnus Myreen. == 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 == We use EasyChair for the refereeing process. The link to the submission page is: https://easychair.org/conferences/?conf=tfp2018 Authors of papers have the choice of having their contributions formally reviewed either before or after the Symposium. == Pre-symposium formal review == Papers to be formally reviewed before the symposium should be submitted before an early deadline and receive their reviews and notification of acceptance for both presentation and publication before the symposium. A paper that has been rejected in this process may still be accepted for presentation at the symposium, but will not be considered for the post-symposium formal review. == Post-symposium formal review == Draft papers will receive minimal reviews and notification of acceptance for presentation at the symposium. 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. == Paper categories == Draft papers and papers submitted for formal review are submitted as 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. == Format == Papers must be written in English, and written using the LNCS style. For more information about formatting please consult the Springer LNCS web site. == Important Dates == Submission (pre-symposium review): March 26, 2018 Submission (draft, post-symposium review): April 26, 2018 Notification (pre- and post-symposium review): May 3, 2018 Registration: June 3, 2018 TFP Symposium: June 11-13, 2018 TFPIE Workshop: June 14, 2018 Student papers feedback: June 21, 2018 Submission (post-symposium review): August 14, 2018 Notification (post-symposium review): September 20, 2018 Camera-ready paper (pre- and post-symposium review): November 30, 2018 == Program Committee == Program Co-chairs Michał Pałka, Chalmers University of Technology (SE) Magnus Myreen, Chalmers University of Technology (SE) Program Committee Soichiro Hidaka, Hosei University (JP) Meng Wang, University of Bristol (UK) Sam Tobin-Hochstadt, Indiana University Bloomington (US) Tiark Rompf, Purdue University (US) Patricia Johann, Appalachian State University (US) Neil Sculthorpe, Nottingham Trent University (UK) Andres Löh, Well-Typed LLP (UK) Tarmo Uustalu, Tallinn University of Technology (EE) Cosmin E. Oancea, University of Copenhagen (DK) Mauro Jaskelioff, Universidad Nacional de Rosario (AR) Peter Achten, Radboud University (NL) Dimitrios Vytiniotis, Microsoft Research (UK) Alberto Pardo, Universidad de la República (UY) Natalia Chechina, University of Glasgow (UK) Peter Sestoft, IT University of Copenhagen (DK) Scott Owens, University of Kent (UK)

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Fwd: Monad Transformers stack with variable depth
by leonidasbo . 07 Mar '18

07 Mar '18

Hello, I am a beginner with Haskell and the last few days I am troubled on how to form a stack of Monad Transformers. The following example demonstrates the use of multiple State monads without the use of Monad Transformers: data Item = Item { rCounter :: Int } increaseCounter :: State Item () increaseCounter = do val <- gets rCounter modify (\i -> i { rCounter = val + 1 }) data ItemManager = ItemManager { rItems :: [Item] } addItem :: Item -> State ItemManager () addItem item = do items <- gets rItems modify (\mgr -> mgr { rItems = items ++ [item] }) increaseCounterInItems :: State ItemManager () increaseCounterInItems = do items <- gets rItems let items' = map *(execState increaseCounter)* items modify (\mgr -> mgr { rItems = items' }) main :: IO () main = $ do let itemMgrState = do addItem $ Item 0 addItem $ Item 10 increaseCounterInItems let itemMgr = execState itemMgrState $ ItemManager [] let items = rItems itemMgr putStrLn rCounter (items !! 0) -- prints 1 putStrLn rCounter (items !! 1) -- prints 11 In the above implementation calls *execState, *inside functions of ItemManager, for updating Items. I have read about MonadTransformers and that they give you the ability to use monads inside the context of another monad. So I would like to use StateT in signatures of ItemManager's functions and avoid calling *execState, *something like this: increaseCounterInltems :: StateT ItemManager (State Item) () But I cannot find a way to implement the above function. The root cause of the difficulty seems to be that ItemManager contains multiple Items. The Monad Transformer stack contains a single State Item. So it seems to me that I am following the wrong approach. How could I use Monad Transformers in order to avoid calling *execState* for modifying Items in ItemManager? Thanks in advance, Leonidas <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campai…> Virus-free. www.avast.com <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campai…> <#m_-5826819471182298913_DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2>

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sv library for your csv|psv|tsv
by Tony Morris 07 Mar '18

07 Mar '18

Hi everyone, The Queensland Functional Programming Lab has released the sv library for parsing, editing and calculating results based on * separated value file formats such as CSV, PSV and TSV. https://hackage.haskell.org/package/sv This first release of the library is 6 months of work by the FP lab. If you are familiar with the original argonaut[^1] library in scala or purescript, you will know of the idea of codecs for converting a syntax tree into your user-defined values. For example, taking a JSON data type to your own Person data type. Some of these ideas have been adapted to the aeson library. The sv library implements these same original ideas, with corrections to a few of the original mistakes that we made in argonaut. The sv library also retains the inverse law to parsing (write . parse = id), so you can use the library for editing CSV|PSV|TSV files. Characters such as whitespace, quotes, etc are retained in the syntax tree. If there are any questions, please feel free to contact us http://qfpl.io/contact [^1]: http://argonaut.io/

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VerifyThis 2018: Call for Participation and Travel Grants
by Andrei Paskevich 06 Mar '18

06 Mar '18

******************************************************************************** VerifyThis Verification Competition 2018 CALL FOR PARTICIPATION -- TRAVEL GRANTS Competition to be held at ETAPS 2018 http://verifythis.ethz.ch ******************************************************************************** IMPORTANT DATES Grant application deadline: March 12, 2018 Competition: April 14 and 15, 2018 ABOUT VerifyThis 2018 is a program verification competition taking place as part of the European Joint Conferences on Theory and Practice of Software (ETAPS 2018) on April 14-15, 2018 in Thessaloniki, Greece. It is the 7th event in the VerifyThis competition series. The competition will offer a number of challenges presented in natural language and pseudo code. Participants have to formalize the requirements, implement a solution, and formally verify the implementation for adherence to the specification. There are no restrictions on the programming language and verification technology used. The correctness properties posed in problems will have the input-output behaviour of programs in focus. Solutions will be judged for correctness, completeness, and elegance. PARTICIPATION: Participation is open for anybody interested. Teams of up to two people are allowed. Registration for ETAPS workshops and physical presence on site is required. We particularly encourage participation of: - student teams (this includes PhD students) - non-developer teams using a tool someone else developed - several teams using the same tool TRAVEL GRANTS: The competition has funds for a limited number of travel grants. A grant covers the incurred travel and accommodation costs up to a certain limit. The expected limit is EUR 350 for those coming from Europe and EUR 600 for those coming from outside Europe. To apply for a travel grant, send an email to verifythis(a)cs.nuim.ie by March 12, 2018. The application should include: - your name - your affiliation - the verification system(s) you plan to use at the competition - the planned composition of your team - a short letter of motivation explaining your involvement with formal verification so far - if you are a student, please state the academic degree you are seeking and have your supervisor send a brief letter of support to verifythis(a)cs.nuim.ie ORGANIZERS * Marieke Huisman, University of Twente, the Netherlands * Rosemary Monahan, Maynooth University, Ireland * Peter Müller, ETH Zürich, Switzerland * Andrei Paskevich, Paris-Sud University, France * Gidon Ernst, National Institute of Informatics Tokyo, Japan CONTACT Email: verifythis(a)cs.nuim.ie Web: http://verifythis.ethz.ch

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missing optimization for (++)
by Ben Franksen 06 Mar '18

06 Mar '18

I found that in base [1] we have (++) [] ys = ys (++) (x:xs) ys = x : xs ++ ys I had expected there to be a clause (++) xs [] = xs at the top, which would avoid the list traversal in this common case. Is this somehow magically taken care of by the {-# RULES "++" [~1] forall xs ys. xs ++ ys = augment (\c n -> foldr c n xs) ys #-} ? No, inlining @augment g xs = g (:) xs@ gives me (\c n -> foldr c n xs) (:) ys = foldr (:) ys xs which still traverses xs even if ys=[]. Any thoughts? [1] http://hackage.haskell.org/package/base-4.10.1.0/docs/src/GHC.Base.html#%2B… Cheers Ben

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Haskell memory model
by Li-yao Xia 05 Mar '18

05 Mar '18

Hello café, What guarantees are there about shared memory concurrency in Haskell? In particular, I'm wondering how to correctly and efficiently synchronize mutable operations from the vector package, using stm or atomic-primops. - Are reads/writes on vectors sequentially consistent? As a concrete example, can the following program (a common test for relaxed memory models) print anything? import qualified Data.Vector.Mutable as MV import Control.Concurrent main :: IO () main = do v <- MV.replicate 2 0 t <- newEmptyMVar forkIO $ do MV.write v 0 1 x <- MV.read v 1 putMVar t x forkIO $ do MV.write v 1 1 x <- MV.read v 0 putMVar t x a <- takeMVar t b <- takeMVar t if a == 0 && b == 0 then putStrLn "Relaxed!" else return () - Do atomic operations (via stm or atomic-primops) imply some constraints between vector operations? As another concrete example, can the snippet linked below ever throw an exception? One thread writes to a vector, and another reads from it, and they communicate via stm to guess whether the read value is safe to evaluate (in one test case the first thread overwrites a defined value with undefined, and in the other case it overwrites undefined with a defined value). http://lpaste.net/362596 Regards, Li-yao

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Re: [Haskell-cafe] missing optimization for (++)
by Markus Läll 05 Mar '18

05 Mar '18

Hi Viktor What I think the OP is asking for is a case where the original list would be returned immediately if the second is empty -- keeping the original spine. Since that case is missing then the list is pattern-matched and then reconstructed. Whether this actually happens after compilation is the real question. On Mar 4, 2018 21:24, "Viktor Dukhovni" <ietf-dane(a)dukhovni.org> wrote: > On Mar 4, 2018, at 4:32 AM, Ben Franksen <ben.franksen(a)online.de> wrote: > > I found that in base [1] we have > > (++) [] ys = ys > (++) (x:xs) ys = x : xs ++ ys > > I had expected there to be a clause > > (++) xs [] = xs > > at the top, which would avoid the list traversal in this common case. > > [...] > > which still traverses xs even if ys=[]. > > Any thoughts? Haskell is lazy, the traversal of x happens only when the combined list is actually traversed, and only for as many elements as requested, so the construction of the concatenated list carries little additional cost. And as pointed out, needlessly forcing the first element of y can have unintended consequences. For example: GHCi, version 8.0.2: http://www.haskell.org/ghc/ :? for help Prelude> let x = [1..] Prelude> let y = [1..] Prelude> let z = x ++ y Prelude> take 20 z [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20] -- Viktor. _______________________________________________ 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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cabal: Couldn't parse the output of 'setup register --gen-pkg-config':NoParse
by Henk-Jan van Tuyl 04 Mar '18

04 Mar '18

L.S., I am trying to get wxHaskell compiled with GHC 8.4.0.20180224 and cabal-install 2.1.0.0; compilation fails with the message: wxcore-0.93.0.0-1L9rVktyK3zIYrrLxBiCr9 failed during the final install step. The exception was: dieVerbatim: user error (cabal: Couldn't parse the output of 'setup register --gen-pkg-config':NoParse "license" 5 ) I am using Windows 8.1. Can anybody tell me what to do about this? Regards, Henk-Jan van Tuyl -- Message from Stanford University: 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://foldingathome.stanford.edu/ -- http://members.chello.nl/hjgtuyl/tourdemonad.html Haskell programming --

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ANN: network-2.6.3.4
by evan＠evan-borden.com 01 Mar '18

01 Mar '18

Announcing network-2.6.3.4 * Don't touch IPv6Only when running on OpenBSD [#227](https://github.com/haskell/network/pull/227) * Do not closeFd within sendFd [#271](https://github.com/haskell/network/pull/271) * Updating examples and docs. A big thanks to the network contributors. http://hackage.haskell.org/package/network-2.6.3.4

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