- Haskell-Cafe - Haskell.org

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 11 Jun '18

11 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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removing a cookie via ghcjs
by Michael Litchard 08 Jun '18

08 Jun '18

Using ghcjs, I am able to read a cookie using getCookie. There's no corresponding remove/deleteCookie that I can find. Could I get some assistance in how to remove the same cookie I can see using getCookie?

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TyDe 2018: SUBMISSION DEADLINE EXTENDED TO JUNE 13th.
by Niki Vazou 07 Jun '18

07 Jun '18

Hey all, the TyDe submission deadline got extended for one week! CALL FOR CONTRIBUTIONS: DEADLINE EXTENDED TO JUNE 13th. TyDe 2018: Type-Driven Development https://icfp18.sigplan.org/track/tyde-2018 23-29 Sep, 2018, St. Louis, Missouri (co-located with ICFP) ============================================== *Call for Contributions* We welcome all contributions, both theoretical and practical, on a range of topics including: dependently typed programming; generic programming; design and implementation of programming languages, exploiting types in novel ways; exploiting typed data, data dependent data, or type providers; static and dynamic analyses of typed programs; tools, IDEs, or testing tools exploiting type information; pearls, being elegant, instructive examples of types used in the derivation, calculation, or construction of programs. *Important Dates* **Extended paper submission deadline: Wednesday, June 13, 2018** Extended abstract deadline: Wednesday, June 13, 2018 Author notification: Friday, June 29, 2018 Deadline for camera ready version: August 5, 2018 Workshop: Thursday, September 27, 2018 *Program Committee* - Guillaume Allais, Radboud University Nijmegen, Netherlands - Zena M. Ariola, University of Oregon, USA - David Darais, University of Vermont, USA - Richard Eisenberg, Bryn Mawr College, USA (co-chair) - Jennifer Hackett, University of Nottingham, UK - Shin-ya Katsumata, National Institute of Informatics, Japan - Daan Leijen, Microsoft Research, USA - Shin-Cheng Mu, Academia Sinica, Taiwan - Dominic Orchard, University of Kent, UK - Peter-Michael Osera, Grinnell College, USA - Zoe Paraskevopoulou, Princeton University, USA - Alberto Pardo, Universidad de la Republica, Uruguay - Matthieu Sozeau, University of Paris Diderot, Paris 7, France - Niki Vazou, University of Maryland, USA (co-chair) *Submission details* Submissions should fall into one of two categories: - Regular research papers (12 pages) - Extended abstracts (2 pages) The bibliography will not be counted against the page limits for either category. Regular research papers are expected to present novel and interesting research results, and will be included in the formal proceedings. Extended abstracts should report work in progress that the authors would like to present at the workshop. Extended abstracts will be distributed to workshop attendees but will not be published in the formal proceedings. We welcome submissions from PC members (with the exception of the two co-chairs), but these submissions will be held to a higher standard. Submission is handled through HotCRP: https://tyde18.hotcrp.com/ All submissions should be in portable document format (PDF) and formatted using the ACM SIGPLAN style guidelines: http://www.sigplan.org/Resources/Author/ Note that the ACM SIGPLAN style guidelines have changed from previous years! In particular, submissions should use the new ‘acmart’ format and the two-column ‘sigplan’ subformat (not to be confused with the one-column ‘acmlarge’ subformat!). Extended abstracts must be submitted with the label ‘Extended abstract’ clearly in the title. Best, Niki Vazou

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Usage of `pure`
by PY 07 Jun '18

07 Jun '18

Hello, Dear Cafe! Consider, I have big application with monad and applicative related code. What problems I can hit if I will replace all `return`s with `pure` (in `do`-blocks, anywhere). So, `return` will be totally eliminated. === Best regards, Paul

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Parsing a matrix table with Data.Frames
by Tyson Whitehead 06 Jun '18

06 Jun '18

I have a case where some of my data is stored in CSV matrix form like this example of a table telling whether person i has pet j ,cat,dog,goldfish bill,true,true,false sue,false,true,true fred,false,false,true I can't see any obvious way to read this sort of thing in with the Data.Frames package. Would love to be told differently. Thanks! -Tyson

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