- Haskell-Cafe - Haskell.org

Lattice and calculation of Least Upper Bounds
by Aaron Gray 16 Jun '18

16 Jun '18

Hi, I am trying to work out how to use the Algebra.Lattice family of Lattice data structures. Firstly how do I construct a lattice ? What I am wanting to do is to be able to construct a lattice to represent a multiple inheritance hierarchy. Then I to be able to find the Least Upper Bound of a set of classes/types. This is in order to find the type of a multiple case expression. I am not sure if the Haskell classes are actually applicable ? but if they are how do I apply them to the following problem please ? -- Aaron Gray Independent Open Source Software Engineer, Computer Language Researcher, Information Theorist, and amateur computer scientist.

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Hedgehog - Integrated shrinking, shrinks obey invariants by construction.
by Petr Pudlák 16 Jun '18

16 Jun '18

Hi everyone, I found the above interesting sentence in Hedgehog's [1] documentation. What does this mean? Is construction there somewhat tied to shrinking, perhaps something like going in the reverse direction? Thanks, Petr [1] https://github.com/hedgehogqa/haskell-hedgehog#features

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Re: [Haskell-cafe] LIA bindings?
by ARJANEN Loïc Jean David 15 Jun '18

15 Jun '18

Hello, It was purely curiosity which made me ask that question given that the report mentions this standard but as you said, if no one maintains it there’s little point in making bindings for it. Regards, ARJANEN Loïc Le 2018-06-13 à 22:48, Richard O'Keefe a écrit : > A couple of years ago I inquired about adding a new module to > the LIA standards to describe binary and decimal fixed point > arithmetic, having run into a standard which deferred the > semantics of its fixed point arithmetic to LIA. That was a > bit odd, because LIA explicitly refused to say anything about > the matter. The result was the implementations not agreeing, > in quite fundamental ways, with each other. I offered a > draft executable specification in Haskell, checked with > QuickCheck. I basically got the answer "nice work, but nobody > in the industry cares about LIA any more, which is why LIA-1 > was revised but LIA-2 and LIA-3 never were and never will be." > > So the question has to be asked: what exactly would be the > benefit in building library code to support a standard that > nobody wants to maintain any more? > > On 13 June 2018 at 20:44, ARJANEN Loïc Jean David > <arjanen.loic(a)gmail.com <mailto:arjanen.loic@gmail.com>> wrote: > > Dear Café, > > I saw in the report that the standard libraries’ operations don’t > conform to LIA and that such operations should be done in an > external library. Does such a library exist? > > Regards, > ARJANEN Loïc > > _______________________________________________ > Haskell-Cafe mailing list > To (un)subscribe, modify options or view archives go to: > http://mail.haskell.org/cgi-bin/mailman/listinfo/haskell-cafe > <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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Call for draft papers for presentation at IFL 2018 (Implementation and Application of Functional Languages)
by Jurriaan Hage 15 Jun '18

15 Jun '18

Hello, Please, find below the fourth 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 --- Call for Draft papers for presentations ================================================================================ 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 [PASSED!] Submission of draft papers: July 17, 2018 [UPCOMING!] 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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How far can you take overloading with type classes?
by Hilco Wijbenga 14 Jun '18

14 Jun '18

Hi all, Given definitions of Line and Lines is it possible to define a type class (or maybe multiple type classes) that would allow for the following: (++) :: Line -> Line -> Lines (++) :: Line -> Lines -> Lines (++) :: Lines -> Line -> Lines (++) :: Lines -> Lines -> Lines I.e. is there a way to overload (++) such that it supports each of these 4 combinations? (Let's ignore that (++) already exists for the moment.) Cheers, Hilco

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CFP: One Month Until Left For Submitting to The Workshop in OCL and Textual Modeling (OCL 2018)
by Achim D. Brucker 14 Jun '18

14 Jun '18

(Apologies for duplicates) ********************************************************** ** Only one month left until the submission deadline! *** ********************************************************** CALL FOR PAPERS 18th International Workshop on OCL and Textual Modeling Co-located with MODELS 2018: ACM/IEEE 21th International Conference on Model Driven Engineering Languages and System, October 14, 2018, Copenhagen, Denmark 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 - Mathematical models and/or formal semantics for textual modeling languages - 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) - Model-driven security using textual modeling languages - 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 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 MODELS 2018 Conference in Copenhagen, Denmark. 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 5 and 7 pages) describing new ideas, innovative tools or position papers. * Full papers (between 10 and 14 pages). in LNCS format. Submissions should be uploaded to [EasyChair](https://easychair.org/conferences/?conf=ocl2018). 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, as part of the MODELS workshop proceedings, in [CEUR](http://www.ceur-ws.org). ## Important Dates - Submission of papers: July 17, 2018 - Notification: August 17, 2018 - Workshop date: October 14, 2018 -- Dr. Achim D. Brucker | Software Assurance & Security | University of Sheffield https://www.brucker.ch | https://logicalhacking.com/blog @adbrucker | @logicalhacking

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LIA bindings?
by ARJANEN Loïc Jean David 13 Jun '18

13 Jun '18

Dear Café, I saw in the report that the standard libraries’ operations don’t conform to LIA and that such operations should be done in an external library. Does such a library exist ? Regards,ARJANEN Loïc

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Re: [Haskell-cafe] Announce: Haskell Platform 8.4.3
by Johannes Waldmann 13 Jun '18

13 Jun '18

> Haskell Platform 8.4.3 Nice. Now I'm wondering - is there an estimated release date for stackage LTS for ghc-8.4.3? That's a genuine question. I know stackage has (a lot) more packages (platform: less than 100?, last LTS: 2474?) so it involves more interfaces (to software, to humans) that can break in many more ways. - J.W.

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Disable default-to-DeriveAnyClass warning with DerivingStrategies?
by Theodore Lief Gannon 12 Jun '18

12 Jun '18

Is there a flag to disable this warning? There's no mystery or surprise to the default, but if I want all three of GeneralizedNewtypeDeriving, DeriveAnyClass and DerivingStrategies enabled, I'm currently stuck with a warning for e.g. deriving (Generic, ToJSON). The only way to use strategy keywords is on standalone deriving lines, which seems unnecessarily verbose.

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how to prevent 'stack' from installing 'ghc'?
by Johannes Waldmann 10 Jun '18

10 Jun '18

Dear Cafe, 'stack' tries to download and install a 'ghc' binary in case 'ghc' in $PATH does not match what is needed for the resolver given in 'stack.yaml' How can I switch this off completely and reliably? I much rather 'stack' just fails when it detects the mismatch. putting 'system-ghc: true' in 'stack.yaml' and '~/.stack/config.yaml' apparently is not enough. 'stack' does warn before downloading, but sometimes I'm not seeing the warning, e.g., because the whole thing is triggered silently from using 'intero'. I do have several ghc executables (built from source) in /opt/ghc/ghc-$version/bin/ghc and I just need to set PATH accordingly. It would be even better if I could tell 'stack' (once and for all) about these locations. I think I understand why 'stack' does what it does (reproducible builds) but I really want to minimize the number of other people's binaries on my machine. I do use the auto-download feature for easier CI builds - so I agree it can be useful. - J.W.

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