April 2018 - Haskell-Cafe

[ANN] Darcs 2.14.0 release
by Guillaume Hoffmann 04 Apr '18

04 Apr '18

Hi all, The Darcs team is pleased to announce the release of Darcs 2.14.0! Darcs is a free, open source revision control system. It is: * Distributed: Every user has access to the full command set, removing boundaries between server and client or committer and non-committers. * Interactive: Darcs is easy to learn and efficient to use because it asks you questions in response to simple commands, giving you choices in your work flow. You can choose to record one change in a file, while ignoring another. As you update from upstream, you can review each patch name, even the full "diff" for interesting patches. * Smart: Originally developed by physicist David Roundy, darcs is based on a unique algebra of patches. Learn more about Darcs on http://darcs.net . # Supported GHC and Cabal versions Darcs 2.14 can be compiled with GHC 8.0, 8.2 and 8.4, and supports Cabal versions from 1.24. # Windows issues Darcs 2.14 received many updates in its support of encoding. However, it may still contain bugs, especially under Windows, a platform for which we have fewer known users. Please let us know if you encounter weird behaviour under Windows. # What's new # ## User Interface ## - fix encoding business, make DARCS_DONT_ESCAPE_8BIT=1 default (Ben Franksen, Ganesh Sittampalam) - show explicit dependencies in `darcs log -s` (Gian Piero Carrubba) - improve bash/zsh completion (Ben, Gian Piero) - no longer print an error message when ctrlc'ing pager (Guillaume Hoffmann) - `darcs help markdown` mentions all files in `_darcs/prefs/` (Guillaume) - add patch index status to `show repo` command (Ben) ## New features ## - per-file conflict marking (Ben) - make it possible to use DARCS_SCP=rsync (Ben) - add --not-in-remote option to unrecord command (Ben) ## Performance ## - plug memory leak and improve efficiency in annotate (Ben) - save unneeded FL/RL reverses in SelectChanges module (Ben) - optimize token replace code and --look-for-replaces (Ben) - no longer show conflicting files on `whatsnew -s`, will reintrodue this feature when it is done efficiently (Guillaume) ## Developer-related ## - separate display and storage of patches (Ben) - support GHC 8.2 and GHC 8.4 (Ganesh) - many refactorings in Darcs.Repository modules and API (Ben, Guillaume) - no longer track build dependencies in Setup.hs, nor use alpha, beta, rc names (Guillaume) - refactor `pull --reorder-patches` (Ben) - refactor SelectChanges (Ben) - remove Patchy typeclass and redundant constaints where possible (Guillaume) - fix build with cabal new-build (Francesco Ariis) - unit and quickcheck tests for inventories (Ben) - throw out all access to bytestring internals from Darcs.Util.ByteString (Ben) - refactor, simplify, and document hunk application (Ben) - drop support of old cache location and SHA1-hashed repos (Guillaume) - rely on GHC's own stack traces for bug reporting (Guillaume) ## Issues resolved in Darcs 2.14 ## - fix mail encoding with '.' or '=' as last character (Timo von Holtz) - issue2526: whatsnew -l --boring should list boring files (Ben) - issue2208: replace detects existing force hunks in working (Ben) - issue2512: author name is written to repository after multiple-choice prompt (Stephan-A. Posselt) - issue2359: convert --export mishandles Unicode filenames (Ben) - issue2545: prevent argument smuggling in SSH repository URLs (Gian Piero) - issue2581: fix rebase pull --reorder (Ben) - issue2575: fix unrevert with rebase (Ben) - issue2579: allow darcs send to work even if no MTA is installed - issue2555: include explicit dependencies in the output of `log -v` (Gian Piero) - issue2569: decoding multibyte characters (Ben) - issue2563: create remote repo in correct format in ssh tests (Ben) - issue2565: create _darcs dir after searching for an existing one (Ben) - issue2567: darcs whatsnew --unified (Ben) - issue2566: avoid renaming across file systems (Ben) - issue2564: delete wrong and irrelevant propConcatPS (Guillaume) - issue2559: remove trailing empty lines in patch header edition (Guillaume) - issue2536: mask out internal matchers in `show files` routing logic (Gian Piero)

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ThEdu'18: Second Call for Extended Abstracts & Demonstrations
by Achim D. Brucker 04 Apr '18

04 Apr '18

(Apologies for duplicates) 2nd Call for Extended Abstracts & Demonstrations ************************************************************************** ThEdu'18 Theorem proving components for Educational software 18 July 2018 http://www.uc.pt/en/congressos/thedu/thedu18 ************************************************************************** affiliated to IJCAR 2018 July 14-17, 2018 Oxford, United Kingdom http://www.ijcar2018.org/ (part of FLoC 2018) ************************************************************************** THedu'18 Scope: Computer Theorem Proving is becoming a paradigm as well as a technological base for a new generation of educational software in science, technology, engineering and mathematics. The workshop brings together experts in automated deduction with experts in education in order to further clarify the shape of the new software generation and to discuss existing systems. Invited Talk Julien Narboux, University of Strasbourg, France Important Dates * Extended Abstracts: 15th April 2018 * Author Notification: 15th May 2018 * Workshop Day: 18 July 2018 Topics of interest include: * methods of automated deduction applied to checking students' input; * methods of automated deduction applied to prove post-conditions for particular problem solutions; * combinations of deduction and computation enabling systems to propose next steps; * automated provers specific for dynamic geometry systems; * proof and proving in mathematics education. Submission We welcome submission of extended abstracts and demonstration proposals presenting original unpublished work which is not been submitted for publication elsewhere. All accepted extended abstracts and demonstrations will be presented at the workshop. The extended abstracts will be made available online. Extended abstracts and demonstration proposals should be submitted via easychair, https://easychair.org/conferences/?conf=thedu18 formatted according to http://www.easychair.org/publications/easychair.zip Extended abstracts and demonstration proposals should be approximately 5 pages in length and are to be submitted in PDF format. At least one author of each accepted extended abstract/demonstration proposal is expected to attend THedu'18 and presents his/her extended abstract/demonstration. Program Committee Francisco Botana, University of Vigo at Pontevedra, Spain Roman Hašek, University of South Bohemia, Czech Republic Filip Maric, University of Belgrade, Serbia Walther Neuper, Graz University of Technology, Austria (co-chair) Pavel Pech, University of South Bohemia, Czech Republic Pedro Quaresma, University of Coimbra, Portugal (co-chair) Vanda Santos, CISUC, Portugal Wolfgang Schreiner, Johannes Kepler University, Austria Burkhart Wolff, University Paris-Sud, France Proceedings The extended abstracts and system descriptions will be available in ThEdu'18 Web-page. After presentation at the conference, selected authors will be invited to submit a substantially revised version, extended to 14--20 pages, for publication by the Electronic Proceedings in Theoretical Computer Science (EPTCS). -- Dr. Achim D. Brucker | Software Assurance & Security | University of Sheffield https://www.brucker.ch | https://logicalhacking.com/blog @adbrucker | @logicalhacking

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Where are rank-3 types necessary in practice for maintaining abstraction?
by Timotej Tomandl 04 Apr '18

04 Apr '18

Hello, So we need rank-2 type in runST :: (forall s. ST <https://hackage.haskell.org/package/base-4.11.0.0/docs/Control-Monad-ST.htm…> s a) -> a, to prevent s from appearing in a. I have been thinking about this for a bit, but I failed to come up with a practical situation, where rank-3 types are necessary for safety of some abstraction. The rank-3 example in here and any other I found, look very synthetic, i.e. limiting computation to id: https://ocharles.org.uk/blog/guest-posts/2014-12-18-rank-n-types.html and compared to the runST example of limiting a scope of a type variable for purposes of safety looks unnatural. Could anyone please point me to a practical example of rank-3 polymorphism, where it is necessary for safety of an abstraction, if it exists? I suspect there is a situation, where rank-3 is necessary for maintaining abstration exists, but I can't think of any. Any ideas about such situations and even better situations where this is used on hackage? Timotej Tomandl

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Database of real faults
by Gabriela Araujo Britto 03 Apr '18

03 Apr '18

Hi, I'd like to know if there exists a database of reproducible real faults in Haskell software, along the lines of defects4j (https://github.com/rjust/ defects4j/), or a related initiative. My intention is to use this for research in mutation testing. Thank you, Gabriela

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2nd CfP: IFL 2018 (30th Symposium on Implementation and Application of Functional Languages)
by Jurriaan Hage 03 Apr '18

03 Apr '18

Hello, Please, find below the second call for papers for IFL 2018. Please forward these to anyone you think may be interested. Apologies for any duplicates you may receive. best regards, Jurriaan Hage Publicity Chair of IFL --- ================================================================================ IFL 2018 30th Symposium on Implementation and Application of Functional Languages University of Massachusetts Lowell, MA, USA September 5th-7th, 2018 http://iflconference.org ================================================================================ ### Scope The goal of the IFL symposia is to bring together researchers actively engaged in the implementation and application of functional and function-based programming languages. IFL 2018 will be a venue for researchers to present and discuss new ideas and concepts, work in progress, and publication-ripe results related to the implementation and application of functional languages and function-based programming. Topics of interest to IFL include, but are not limited to: - language concepts - type systems, type checking, type inferencing - compilation techniques - staged compilation - run-time function specialization - run-time code generation - partial evaluation - (abstract) interpretation - metaprogramming - generic programming - automatic program generation - array processing - concurrent/parallel programming - concurrent/parallel program execution - embedded systems - web applications - (embedded) domain specific languages - security - novel memory management techniques - run-time profiling performance measurements - debugging and tracing - virtual/abstract machine architectures - validation, verification of functional programs - tools and programming techniques - (industrial) applications ### Keynote Speakers * Adam Chlipala, Massachusetts Institute of Technology CSAIL * Arjun Guha, University of Massachusetts Amherst ### Submissions and peer-review Differently from previous editions of IFL, IFL 2018 solicits two kinds of submissions: * Regular papers (12 pages including references) * Draft papers for presentations ('weak' limit between 8 and 15 pages) Regular papers will undergo a rigorous review by the program committee, and will be evaluated according to their correctness, novelty, originality, relevance, significance, and clarity. A set of regular papers will be conditionally accepted for publication. Authors of conditionally accepted papers will be provided with committee reviews along with a set of mandatory revisions. Regular papers not accepted for publication will be considered as draft papers, at the request of the author. Draft papers will be screened to make sure that they are within the scope of IFL, and will be accepted for presentation or rejected accordingly. Prior to the symposium: Authors of conditionally accepted papers and accepted presentations will submit a pre-proceedings version of their work that will appear in the draft proceedings distributed at the symposium. The draft proceedings does not constitute a formal publication. We require that at least one of the authors present the work at IFL 2018. After the symposium: Authors of conditionally accepted papers will submit a revised versions of their paper for the formal post-proceedings. The program committee will assess whether the mandatory revisions have been adequately addressed by the authors and thereby determines the final accept/reject status of the paper. Our interest is to ultimately accept all conditionally accepted papers. If you are an author of a conditionally accepted paper, please make sure that you address all the concerns of the reviewers. Authors of accepted presentations will be given the opportunity to incorporate the feedback from discussions at the symposium and will be invited to submit a revised full article for the formal post-proceedings. The program committee will evaluate these submissions according to their correctness, novelty, originality, relevance, significance, and clarity, and will thereby determine whether the paper is accepted or rejected. ### Publication The formal proceedings will appear in the International Conference Proceedings Series of the ACM Digital Library. At no time may work submitted to IFL be simultaneously submitted to other venues; submissions must adhere to ACM SIGPLAN's republication policy: http://www.sigplan.org/Resources/Policies/Republication ### Important dates Submission of regular papers: May 25, 2018 Submission of draft papers: July 17, 2018 Regular and draft papers notification: July 20, 2018 Deadline for early registration: August 8, 2018 Submission of pre-proceedings version: August 29, 2018 IFL Symposium: September 5-7, 2018 Submission of papers for post-proceedings: November 7, 2018 Notification of acceptance: December 22, 2018 Camera-ready version: February 10, 2019 ### Submission details All contributions must be written in English. Papers must use the ACM two columns conference format, which can be found at: http://www.acm.org/publications/proceedings-template Authors submit through EasyChair: https://easychair.org/conferences/?conf=ifl2018 ### Peter Landin Prize The Peter Landin Prize is awarded to the best paper presented at the symposium every year. The honored article is selected by the program committee based on the submissions received for the formal review process. The prize carries a cash award equivalent to 150 Euros. ### Organization and Program committee Chairs: Jay McCarthy & Matteo Cimini, University of Massachusetts Lowell, USA Program Committee: * Arthur Chargueraud, Inria, FR * Ben Delaware, Purdue University, USA * Christos Dimoulas, Northwestern University, USA * David Darais, University of Vermont, USA * Dominic Orchard, University of Kent, UK * Ekaterina Komendantskaya, Heriot-Watt University, UK * Garrett Morris, University of Kansas, USA * Heather Miller, EPFL & Northeastern University, CH & USA * Jeremy Yallop, University of Cambridge, UK * Keiko Nakata, SAP Innovation Center Potsdam, DE * Laura Castro, University of A Coruna, ESP * Magnus Myreen, Chalmers University of Technology, SWE * Natalia Chechina, Bournemouth University, UK * Peter Achten, Radboud Universiteit Nijmegen, NL * Peter-Michael Osera, Grinnell College, USA * Richard Eisenberg, Bryn Mawr College, USA * Trevor McDonell, University of New South Wales, AUS * Yukiyoshi Kameyama, University of Tsukuba, JAP ### Venue The 30th IFL is organized by the University of Massachusetts Lowell. The City of Lowell is located at the heart of the Merrimack Valley just 30 miles northwest of Boston. Lowell can be easily reached by train or taxi. See the website for more information on the venue. ### Acknowledgments This call-for-papers is an adaptation and evolution of content from previous instances of IFL. We are grateful to prior organizers for their work, which is reused here. A part of IFL 2018 format and CFP language that describes conditionally accepted papers has been adapted from call-for-papers of OOPSLA conferences.

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WST 2018 - 2nd Call for Papers (submission: April 15, 2018)
by Salvador Lucas 03 Apr '18

03 Apr '18

========================================================================== WST 2018 - Call for Papers 16th International Workshop on Termination July 18-19, 2017, Oxford, United Kingdom http://wst2018.webs.upv.es/ ========================================================================== The Workshop on Termination (WST) traditionally brings together, in an informal setting, researchers interested in all aspects of termination, whether this interest be practical or theoretical, primary or derived. The workshop also provides a ground for cross-fertilization of ideas from the different communities interested in termination (e.g., working on computational mechanisms, programming languages, software engineering, constraint solving, etc.). The friendly atmosphere enables fruitful exchanges leading to joint research and subsequent publications. The workshop is held as part of the 2018 Federated Logic Conference (FLoC 2018) http://www.floc2018.org/ IMPORTANT DATES: * submission deadline: April 15, 2018 * notification: May 15, 2018 * final version due: May 31, 2018 * workshop: July 18-19, 2018 TOPICS: The 16th International Workshop on Termination welcomes contributions on all aspects of termination. In particular, papers investigating applications of termination (for example in complexity analysis, program analysis and transformation, theorem proving, program correctness, modeling computational systems, etc.) are very welcome. Topics of interest include (but are not limited to): * abstraction methods in termination analysis * certification of termination and complexity proofs * challenging termination problems * comparison and classification of termination methods * complexity analysis in any domain * implementation of termination methods * non-termination analysis and loop detection * normalization and infinitary normalization * operational termination of logic-based systems * ordinal notation and subrecursive hierarchies * SAT, SMT, and constraint solving for (non-)termination analysis * scalability and modularity of termination methods * termination analysis in any domain (lambda calculus, declarative programming, rewriting, transition systems, etc.) * well-founded relations and well-quasi-orders COMPETITION: Since 2003, the catalytic effect of WST to stimulate new research on termination has been enhanced by the celebration of the Termination Competition and its continuously developing problem databases containing thousands of programs as challenges for termination analysis in different categories, see http://termination-portal.org/wiki/Termination_Competition In 2018, the Termination Competition will run in parallel with FLoC 2018. More details will be provided in a dedicated announcement on the competition. PROGRAM COMMITTEE: Cristina Borralleras - U. de Vic Ugo Dal Lago - U. degli Studi di Bologna Carsten Fuhs - Birkbeck, U. of London Samir Genaim - U. Complutense de Madrid Juergen Giesl - RWTH Aachen Raul Gutiérrez - U. Politecnica de València Keiichirou Kusakari - Gifu University Salvador Lucas (chair) - U. Politecnica de Valencia Fred Mesnard - U. de La Reunion Aart Middeldorp - U. of Innsbruck Albert Rubio - U. Politecnica de Catalunya Rene Thiemann - U. of Innsbruck Caterina Urban - ETH Zürich INVITED SPEAKERS: tba SUBMISSION: Submissions are short papers/extended abstracts which should not exceed 5 pages. There will be no formal reviewing. In particular, we welcome short versions of recently published articles and papers submitted elsewhere. The program committee checks relevance and provides additional feedback for each submission. The accepted papers will be made available electronically before the workshop. Papers should be submitted electronically via the submission page: https://easychair.org/conferences/?conf=wst2018 Please, use LaTeX and the LIPIcs style file http://drops.dagstuhl.de/styles/lipics/lipics-authors.tgz to prepare your submission.

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vector-sized: (//) Finites to Ints?
by David Banas 02 Apr '18

02 Apr '18

When did the vector-sized (//) operator change from expecting Finites to expecting Ints?

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[ANNOUNCE] GHC 8.4.2-rc1 now available
by Ben Gamari 02 Apr '18

02 Apr '18

Hello everyone, The GHC team is proud to announce the first release candidate of 8.4.2. the source distribution, binary distributions, and documentation are available at https://downloads.haskell.org/~ghc/8.4.2-rc1 This release follows so closely to 8.4.1 due to a number last-minute bug-fixes that didn't quite make it into 8.4.1. This includes fixes for: * #14705, the interpreter being broken on some systems * #14779, where the compiler produces invalid code when used with -g * #14891, where a selection of GHC testsuite cases fail on OS X * #5129, where the simplifier would incorrectly reorder evaluation in under some conditions. Since this is a relatively small bugfix release we are bypassing the alpha releases and moving right to the release candidate stage. If all goes well the final release will be cut next week. Happy testing Cheers, - Ben

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Architecture for reflex based applications
by Robert Klotzner 02 Apr '18

02 Apr '18

Hi there! I did a little write up about structuring reflex applications, which seems to work out really well for me. Check it out here: https://github.com/gonimo/gonimo/blob/master/front/doc/Gonimo-Architecture.… I would love to hear your thoughts! Best regards, Robert

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json-autotype 1.1.2, and type-providers initiative
by Michal J Gajda 02 Apr '18

02 Apr '18

Hi, I am pleased to announce new version of json-autotype. Highlights of the version: 1. GHC 8.4 support. 2. Preliminary support for Elm output (with more Haskell-family languages coming) 3. Peter Simons has joined the team as official maintainer. 4. Ask us anything on Gitter: https://gitter.im/dataHaskell/json-autotype Json-Autotype team, and Data Haskell Frames team is also pleased to announce `type-providers` initiative that aims to provide standard API for type providers for Haskell family of languages. (Please join us on Gitter: https://gitter.im/dataHaskell/type-providers and https://gitter.im/dataHaskell/DataFrames) -- Cheers Michal J. Gajda

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