- Haskell-Cafe - Haskell.org

[ANN] lzlib bindings in Haskell
by Vanessa McHale 15 Sep '19

15 Sep '19

Hi all, I have released a library containing a high-level API for lzlib (and bindings to the full lzlib), viz. http://hackage.haskell.org/package/lzlib Cheers, Vanessa McHale

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parallele tolistM of the pipes module
by PICCA Frederic-Emmanuel 12 Sep '19

12 Sep '19

Hello, I would like to know how to write a parallele version of the pipes function: toListM :: Monad m => Producer a m () -> m [a] toListM = fold step begin done where step x a = x . (a:) begin = id done x = x [] {-# INLINABLE toListM #-} I want to extract all the a from th epipes but concurrently. is it possible ? Cheers Frederic

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[POPL2020] Call for student volunteers
by Hanneli Tavante 11 Sep '19

11 Sep '19

Hello! The call for Student Volunteers at POPL2020 is opened until October 17th! The 2020 edition will be in New Orleans, USA, January19th-25th. More information here: https://popl20.sigplan.org/attending/students We encourage all the students to apply - with or without experience, local and non-local, undergrads and graduate students.

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Taking over regex-base on Hackage
by Troels Henriksen 10 Sep '19

10 Sep '19

regex-base is at the bottom of the regex-* package hierarchy and has remarkably remained unchanged and working since the last release in 2010. Alas, the MonadFail change in GHC 8.8 breaks it and the maintainer, Christopher Kuklewicz, seems to have been absent for a while. Most of his other packages have long since been taken over by others. I would like to take over regex-base in order to patch it to work with GHC 8.8. -- \ Troels /\ Henriksen

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Concurrent reads, ordered writes?
by amindfv＠gmail.com 09 Sep '19

09 Sep '19

I've implemented a solution for this problem, but it seems a bit less clean than it could be, which leaves me wondering if there's a data structure or algorithm specifically for this purpose: We've got multiple concurrent thereads reading items from a (TBQueue A), calling f :: A -> B, and writing to a (TBQueue B). We must, though, write items into the (TBQueue B) in the order that the corresponding As were read (the order they were put in the (TBQueue A)). Are there existing libraries which solve this or a similar problem? Ideally with niceties like configuring whether the pending out-of-order writes block the worker threads, and a way of signalling there's no more work to perform. Thanks! Tom

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[CC2020] 2nd CFP for the ACM SIGPLAN 2020 International Conference on Compiler Construction
by Gabriel Rodríguez Álvarez 09 Sep '19

09 Sep '19

ACM SIGPLAN 2020 International Conference on Compiler Construction (CC'20) co-located with CGO, PPoPP and HPCA San Diego, CA, USA February 22 - 23, 2020 https://conf.researchr.org/home/CC-2020 The ACM SIGPLAN 2020 International Conference on Compiler Construction (CC 2020) is interested in work on processing programs in the most general sense: analyzing, transforming or executing input programs that describe how a system operates, including traditional compiler construction as a special case. Original contributions are solicited on the topics of interest which include, but are not limited to: - Compilation and interpretation techniques, including program representation, analysis, and transformation; code generation, optimization, and synthesis; the verification thereof - Run-time techniques, including memory management, virtual machines, and dynamic and just-in-time compilation - Programming tools, including refactoring editors, checkers, verifiers, compilers, debuggers, and profilers - Techniques for specific domains, such as secure, parallel, distributed, embedded or mobile environments - Design and implementation of novel language constructs, programming models, and domain-specific languages CC 2020 is the 29th edition of the conference. From this year onwards, CC is an ACM SIGPLAN conference and will implement guidelines and procedures recommended by SIGPLAN https://www.sigplan.org. ================================================================================================= To subscribe to the CC announce mailing list, see cc_conference_announce(a)googlegroups.com To subscribe to the CC announce Twitter account, see @cc2020conf (https://twitter.com/cc2020conf) ================================================================================================= IMPORTANT DATES Abstract Submission: 23 October 2019 Paper Submission : 30 October 2019 Rebuttal : 4-6 December 2019 Artifact Submission: 13 December 2019 Author Notification: 24 December 2019 Final papers due : 15 January 2020 Conference : 22–23 February 2020 All submissions must be made electronically through the conference web site and include an abstract (100–400 words), author contact information, the full list of authors and their affiliations. Full paper submissions must be in PDF formatted printable on both A4 and US letter size paper. All papers must be prepared in ACM Conference Format using the 2-column acmart format. Papers should contain a maximum of 10 pages of text (in a typeface no smaller than 10 point) or figures, NOT INCLUDING references. There is no page limit for references and they must include the name of all authors (not {et al.}). Appendices are not allowed, but the authors may submit supplementary material, such as proofs or source code; all supplementary material must be in PDF or ZIP format. Looking at supplementary material is at the discretion of the reviewers. Submission is double blind and authors will need to identify any potential conflicts of interest with PC, as defined here: http://www.sigplan.org/Resources/Policies/Review/ (ACM SIGPLAN policy). Authors are encouraged to submit their artifacts for the Artifact Evaluation (AE). The Artifact Evaluation process is run by a separate committee whose task is to assess how the artifacts support the work described in the papers. To ease the organization of the AE committee, we kindly ask authors to submit their artifact at the latest 10 days after the rebuttal. Papers that go through the Artifact Evaluation process successfully will receive a seal of approval printed on the papers themselves. Additional information will be made available on the CC AE web page. Deadlines expire at midnight anywhere on earth. ORGANIZERS General Chair Louis-Noel Pouchet Colorado State University <pouchet AT colostate.edu> Program Chair Alexandra Jimborean Uppsala University <alexandra.jimborean AT it.uu.se> Artifact Evaluation Chairs Michel Steuwer University of Glasgow <Michel.Steuwer AT glasgow.ac.uk> Martin Kong University of Oklahoma Publicity Chair Gabriel Rodriguez University of A Coruna Web Chair Mihail Popov Uppsala University Steering Committee Bjorn Franke University of Edinburgh <bfranke AT inf.ed.ac.uk> Sebastian Hack Saarland University Manuel Hermenegildo IMDEA SW Institute and Technical U. of Madrid Peng Wu Huawei America Research Lab Ayal Zaks Intel and Technion, Israel Jingling Xue University of New South Wales, Australia Christophe Dubach University of Edinburgh Nelson J. Amaral University of Alberta Milind Kulkarni Purdue University Program Committee Apan Qasem AMD/Texas State University Bernhard Scholz University of Sydney Bettina Heim Microsoft Bilha Mendelson Optitura Brian Demsky UC Irvine Changhee Jung Virginia Tech Christian Schulte KTH EJ Park Los Alamos National Laboratory Delphine Demange Inria Dongyoon Lee Virginia Tech Fernando Magno Quintao Pereira UFMG Brazil Haowei Wu Google Manuel Hermenegildo IMDEA and T.U. Madrid Matin Hashemi Sharif University of Technology Michel Steuwer University of Glasgow Mila Dalla Preda University of Verona Nelson J. Amaral University of Alberta Philippe Clauss University of Strasbourg Pavlos Petoumenos University of Edinburgh Rumyana Neykova Brunel London Santosh Nagarakatte Rutgers University Sebastian Hack University of Saarland Tomofumi Yuki Inria Xu Liu College of William and Mary

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Re: [Haskell-cafe] [ANNOUNCE] GHC 8.8.1 and cabal-install version
by Carter Schonwald 06 Sep '19

06 Sep '19

V1 or v2 install? On Mon, Sep 2, 2019 at 11:42 AM George Colpitts <george.colpitts(a)gmail.com> wrote: > https://www.haskell.org/ghc/blog/20190825-ghc-8.8.1-released.html says > > cabal-install users should note that cabal-install-3.0 or later is > required for use with GHC 8.8. > > but this seems wrong or have I done something wrong? > > $ cabal install cabal-install > cabal install cabal-install > ... > > Resolving dependencies... > cabal: Could not resolve dependencies: > [__0] trying: cabal-install-3.0.0.0 (user goal) > [__1] next goal: time (dependency of cabal-install) > [__1] rejecting: time-1.9.3/installed-1.9... (conflict: cabal-install => > base>=4.8 && <4.13, time => base==4.13.0.0/installed-4.1...) > [__1] trying: time-1.9.3 > [__2] next goal: stm (dependency of cabal-install) > [__2] rejecting: stm-2.5.0.0/installed-2.5... (conflict: cabal-install => > base>=4.8 && <4.13, stm => base==4.13.0.0/installed-4.1...) > [__2] trying: stm-2.5.0.0 > [__3] next goal: process (dependency of cabal-install) > [__3] rejecting: process-1.6.5.1/installed-1.6... (conflict: cabal-install > => > base>=4.8 && <4.13, process => base==4.13.0.0/installed-4.1...) > [__3] trying: process-1.6.5.1 > [__4] next goal: pretty (dependency of cabal-install) > [__4] rejecting: pretty-1.1.3.6/installed-1.1... (conflict: cabal-install > => > base>=4.8 && <4.13, pretty => base==4.13.0.0/installed-4.1...) > [__4] trying: pretty-1.1.3.6 > [__5] next goal: network (dependency of cabal-install) > [__5] rejecting: network-3.1.0.1/installed-CeX... (conflict: cabal-install > => > base>=4.8 && <4.13, network => base==4.13.0.0/installed-4.1...) > [__5] trying: network-3.1.0.1 > [__6] trying: hackage-security-0.5.3.0 (dependency of cabal-install) > [__7] next goal: template-haskell (dependency of hackage-security) > [__7] rejecting: template-haskell-2.15.0.0/installed-2.1... (conflict: > cabal-install => base>=4.8 && <4.13, template-haskell => > base==4.13.0.0/installed-4.1...) > [__7] rejecting: template-haskell-2.15.0.0, template-haskell-2.14.0.0, > template-haskell-2.13.0.0, template-haskell-2.12.0.0, > template-haskell-2.11.1.0, template-haskell-2.11.0.0, > template-haskell-2.10.0.0, template-haskell-2.9.0.0, > template-haskell-2.8.0.0, > template-haskell-2.7.0.0, template-haskell-2.6.0.0, > template-haskell-2.5.0.0, > template-haskell-2.4.0.1, template-haskell-2.4.0.0, > template-haskell-2.3.0.1, > template-haskell-2.3.0.0, template-haskell-2.2.0.0 (constraint from > non-upgradeable package requires installed instance) > [__7] fail (backjumping, conflict set: cabal-install, hackage-security, > template-haskell) > After searching the rest of the dependency tree exhaustively, these were > the > goals I've had most trouble fulfilling: base, cabal-install, directory, > template-haskell, process, time, network, pretty, hackage-security, > deepseq, > HTTP, stm, cabal-install:lib > > > On Mon, Aug 26, 2019 at 6:25 AM Ben Gamari <ben(a)well-typed.com> wrote: > >> >> Hello everyone, >> >> The GHC team is pleased to announce the release candidate for GHC 8.8.1. >> The source distribution, binary distributions, and documentation are >> available at >> >> https://downloads.haskell.org/ghc/8.8.1 >> >> This release is the culmination of over 3000 commits by over one hundred >> contributors and has several new features and numerous bug fixes >> relative to GHC 8.6: >> >> * Visible kind applications are now supported (GHC Proposal #15) >> >> * Profiling now works correctly on 64-bit Windows (although still may >> be problematic on 32-bit Windows due to platform limitations; see >> #15934) >> >> * A new code layout algorithm for amd64's native code generator >> significantly improving the runtime performance of some kernels >> >> * The introduction of a late lambda-lifting pass which may reduce >> allocations significantly for some programs. >> >> * Further work on Trees That Grow, enabling improved code re-use of the >> Haskell AST in tooling >> >> * Users can write `forall` in more contexts (GHC Proposal #7) >> >> * The pattern-match checker is now more precise in the presence of >> strict fields with uninhabited types. >> >> * A comprehensive audit of GHC's memory ordering barriers has been >> performed, resulting in a number of fixes that should significantly >> improve the reliability of programs on architectures with >> weakly-ordered memory models (e.g. PowerPC, many ARM and AArch64 >> implementations). >> >> * A long-standing linker limitation rendering GHCi unusable with >> projects with cyclic symbol dependencies has been fixed (#13786) >> >> * Further work on the Hadrian build system >> >> * Countless miscellaneous bug-fixes >> >> Unfortunately, due to a build issue (#17108) found late in the release >> process >> i386 Windows builds are currently unavailable. These will be provided in >> the coming weeks. >> >> As always, if anything looks amiss do let us know. >> >> Happy compiling! >> >> Cheers, >> >> - Ben >> >> >> [1] >> https://downloads.haskell.org/ghc/8.8.1/docs/html/users_guide/8.8.1-notes.h… >> _______________________________________________ >> Glasgow-haskell-users mailing list >> Glasgow-haskell-users(a)haskell.org >> http://mail.haskell.org/cgi-bin/mailman/listinfo/glasgow-haskell-users >> > _______________________________________________ > Glasgow-haskell-users mailing list > Glasgow-haskell-users(a)haskell.org > http://mail.haskell.org/cgi-bin/mailman/listinfo/glasgow-haskell-users >

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How to write a Monad instance for this type
by PICCA Frederic-Emmanuel 06 Sep '19

06 Sep '19

Hello, I try to write a monad instance for this type which represent the content of an hdf5 file. This file format is similar to a filesystem, where directories are Group and files Dataset. I end up with this type. data Hdf5M a = H5Root (Hdf5M a) | H5Group ByteString [Hdf5M a] -- A group can contain other groups and/or datasets | forall sh b. (NativeType b, Shape sh) => H5Dataset ByteString (Array F sh b) type Hdf5 = Hdf5M () hdf5 :: Hdf5 -> Hdf5 hdf5 = H5Root group :: ByteString -> [Hdf5] -> Hdf5 group g = H5Group g dataset :: (NativeType b, Shape sh) => ByteString -> (Array F sh b) -> Hdf5 dataset = H5Dataset I tryed to inspire myself from the blaze-html Markup type. And I would like to be able to describe a contain like this hdf5 $ do group "name" $ do dataset "name1" array1 dataset "name2" array2 group "other-name" $ do etc... instead of H5Root ( H5Group "name" [ dataset ]...) the final idea, is to be able to serialize object via a class ToHdf5 where toHdf5 :: a -> Hdf5 So my question is someone can help me design this ? thanks for your help Frederic

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Stack & Test Coverage
by Hilco Wijbenga 06 Sep '19

06 Sep '19

Hi all, I have a very simple newtype Index = Index Int deriving (Eq, Ord, Enum) for which I have written tests with both HSpec and QuickCheck. Specifically, I have written tests for "==", "/=", "compare" (for all of EQ, LT, and GT), and "toEnum" & "fromEnum". So I thought I had _very_ thoroughly covered that one line. :-) Unfortunately, after running "stack clean ; stack test --coverage" I see in the HTML report that only Eq has been tested and that Ord and Enum have _no_ coverage (i.e. "never executed"). (The module also has some regular functions and an explicit Show instance [all with tests] and those are apparently fine. So coverage does seem to work but not the way I expect?) What am I doing wrong? Cheers, Hilco

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c2hs syntax highlighting in vim
by Vanessa McHale 05 Sep '19

05 Sep '19

Hi all, I wrote a vim plugin to highlight c2hs files, viz. https://github.com/vmchale/c2hs-vim Cheers, Vanessa McHale

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