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Re: [Haskell-cafe] Gitter Haskell Community
by Ben Spencer 07 Dec '16

07 Dec '16

Hello Tomas, I agree usability does matter. On Dec 07, 2016, at 11:55 AM, Ben Spencer <ben.richard.spencer(a)me.com> wrote: Hello Tomas, I agree usability does matter. On Dec 07, 2016, at 11:51 AM, Tomas Carnecky <tomas.carnecky(a)gmail.com> wrote: Usability matters. It's easier to tell people to open a browser window and point them at a URL than tell them to download an IRC chat client and how to connect to the server and... On Wed, Dec 7, 2016 at 5:41 PM William Yager <will.yager(a)gmail.com> wrote: What are the advantages of this over the #haskell IRC on freenode? It's very active, usually with over 1500 nicks at any given time. I generally prefer IRC to any of these hip web chat solutions because IRC is client-agnostic and very rugged against companies folding or deciding they don't want to host a project any more. Basically the only way to kill an IRC channel is through social attrition, whereas any social value built up in hosted chat services might disappear overnight. The one major advantage of hosted chats over IRC is that they work better with mobile users, but I don't think that's very relevant for haskell dev. Will On Wed, Dec 7, 2016 at 7:34 AM, Ben Spencer <ben.richard.spencer(a)me.com> wrote: Why Gitter you might ask? _______________________________________________ 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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State of records in Haskell
by Øystein Kolsrud 07 Dec '16

07 Dec '16

Hi! I recently had a look at a talk by Simon Peyton Jones on lenses (https://skillsmatter.com/skillscasts/4251-lenses-compositional-data-access-…) and happened to notice that, at the very end, he mentions that there were changes going into GHC 7.10 that would make it possible to use the same field name for multiple record types. I was searching around a little for more information on this, but had a hard time finding what I was looking for and was hoping that someone here could give me a pointer. What does GHC support in this domain at the moment, and are there any particular flags I need to use in order to use that functionality? Best regards, Øystein Kolsrud

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CFP Bx 17: 6th International Workshop on Bidirectional Transformations
by Meng Wang 07 Dec '16

07 Dec '16

CFP Bx 17: 6th International Workshop on Bidirectional Transformations CALL FOR PAPERS Sixth International Workshop on Bidirectional Transformations (Bx 2017) Uppsala, Sweden (Saturday April 29th, as part of ETAPS 2017) http://bx-community.wikidot.com/bx2017:home Bidirectional transformations (bx) are a mechanism for maintaining the consistency of at least two related sources of information. Such sources can be relational databases, software models and code, or any other document following standard or ad-hoc formats. Bx are an emerging topic in a wide range of research areas, with prominent presence at top conferences in several different fields (namely databases, programming languages, software engineering, and graph transformation), but with results in one field often getting limited exposure in the others. Bx 2017 is a dedicated venue for bx in all relevant fields, and is part of a workshop series that was created in order to promote cross-disciplinary research and awareness in the area. As such, since its beginning in 2012, the workshop has rotated between venues in different fields. IMPORTANT DATES - Abstract submission: 20 Jan 2017 - Paper submission: 27 Jan 2017 - Author notification: 17 Feb 2017 - Camera-ready version: 1 March 2017 - Workshop date: 29 April 2017 AIMS AND TOPICS The aim of the workshop is to bring together researchers and practitioners, established and new, interested in bx from different perspectives, including but not limited to: - data and model synchronization - view updating - inter-model consistency analysis and repair - data/schema (or model/metamodel) co-evolution - coupled software/model transformations - inversion of transformations and data exchange mappings - domain-specific languages for bx - analysis and classification of requirements for bx - bridging the gap between formal concepts and application scenarios - analysis of efficiency of transformation algorithms and benchmarks - survey and comparison of bx technologies - case studies and tool support PAPER CATEGORIES Submissions to Bx 2017 can be: - Regular papers (up to 15 pages) - in-depth presentations of novel concepts and results - applications of bx to new domains - survey papers providing novel comparisons between existing bx technologies and approaches - case studies - Tool papers (up to 8 pages) - guideline papers presenting best practices for employing a specific bx approach (with a specific tool) - presentation of new tools or substantial improvements to existing ones - qualitative and/or quantitative comparisons of applying different bx approaches and tools - Short papers (up to 4 pages) - work in progress - small focused contributions - position papers and research perspectives - critical questions and challenges for bx - Talk proposals (up to 2 pages) - proposed lectures about topics of interest for bx - existing work representing relevant contributions for bx - promising contributions that are not mature enough to be proposed as papers of the other categories All papers are expected to be self-contained and well-written. Tool papers are not expected to present novel scientific results, but to document artifacts of interest and share bx experience/best practices with the community. Short papers should primarily provoke interesting discussion at the workshop and will not be held to the same standard of maturity as regular papers. Talk proposals are expected to present works of particular interest for the community and that are worth a talk slot at the workshop. We strongly encourage authors to ensure that any (variants of) examples are present in the bx example repository at the time of submission, and for tool papers, to allow for reproducibility with minimal effort, either via a virtual machine (e.g. via Share - http://share20.eu) or a dedicated website with relevant artifacts and tool access. SUBMISSION GUIDELINES Submitted papers must follow the CEUR one column style available at http://ceur-ws.org/Vol-XXX/samplestyles/. Papers must be submitted via the EasyChair system: https://www.easychair.org/conferences/?conf=bx2017. Submissions not complying with the above guidelines may be excluded from the reviewing process without further notice. If a paper is accepted, one author of the paper is expected to participate in the workshop to present it. Authors of accepted tool papers are also expected to be available to demonstrate their tool at the event. PROCEEDINGS AND SPECIAL ISSUE The workshop proceedings, including all accepted papers (except talk proposals), will be published electronically by CEUR (http://ceur-ws.org) Authors of accepted papers (of all categories except talk proposal) that have high-quality and the potential to be extended into journal articles will be invited to submit a revised and extended version of their paper to an expected special issue of the Journal of Object Technology (http://www.jot.fm) these papers will then be subject to a careful reviewing and selection process according to the scientific standards of the Journal of Object Technology. PROGRAM CO-CHAIRS - Romina Eramo, University of L'Aquila, Italy - Michael Johnson, Macquarie University, Australia PROGRAM COMMITTEE MEMBERS - Anthony Anjorin, University of Paderborn, Germany - Soichiro Hidaka, Hosei University, Japan - Max E. Kramer, Karlsruhe Institute of Technology, Germany - James McKinna, University of Edinburgh, UK - Hugo Pacheco, University of Minho, Portugal - Alfonso Pierantonio, University of L'Aquila, Italy - Andy Schürr, Technical University of Darmstadt, Germany - Daniel Strüber, Universität Koblenz-Landau, Germany - James Terwilliger, Microsoft, USA - Meng Wang, University of Kent, UK - Bernhard Westfechtel, Universität Bayreuth, Germany - Manuel Wimmer, Vienna University of Technology, Austria +++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Dr. Meng Wang | Lecturer in Computer Science School of Computing | University of Kent | Canterbury, Kent, CT2 7NF, UK m.w.wang(a)kent.ac.uk<mailto:m.w.wang@kent.ac.uk> | www.cs.kent.ac.uk/~mw516<http://www.cs.kent.ac.uk/~mw516> +++++++++++++++++++++++++++++++++++++++++++++++++++++++++

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Qualified imports and REPL output in GHCi 8.0.1
by Atrudyjane 07 Dec '16

07 Dec '16

When I do a qualified import such as: λ> import qualified Data.Bool then query a type, this is the output. λ> :t Data.Bool.bool Data.Bool.bool :: a -> a -> Bool -> a Was expecting: λ> :t Data.Bool.bool Data.Bool.bool :: a -> a -> Data.Bool.bool -> a I experimented with changing the -fno-implicit-import-qualified flag and the result was the same. Is there an option that needs to be set to show the expected behavior? Regards, Andrea Sent with [ProtonMail](https://protonmail.com) Secure Email.

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Use of errorWithoutStackTrace in the Prelude
by Alexis King 07 Dec '16

07 Dec '16

Hello, I noticed that the partial functions in the Prelude use errorWithoutStackTrace instead of `error` to provide their error messages, which produces significantly worse error messages. I stumbled into this when a coworker of mine had trouble tracking down a use of `head` that was throwing an exception, but didn’t include any information about where it was in the source. What exactly is the rationale for this? Is it to avoid the performance penalty of passing around the implicit parameter? That seems relatively unlikely, since the performance hit seems trivial, but perhaps it’s to avoid breaking tests that depend on error messages? I think it would be nice for Prelude-provided functions to be informative by default, so the change seems worth it to me, but I’m wondering if there’s something I’ve overlooked. Also, if the answer really is “no, errorWithoutStackTrace is correct”, is the expectation that people will use -prof if they want stacks? This seems a bit frustrating to a newcomer who might not understand anything more complicated than running `stack test` and might not be able to figure out how to pass the right options (especially since options need to be passed both at compile-time and at runtime). Thanks, Alexis

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Re: [Haskell-cafe] stack setup errors when user name has accents
by Andre Fernandes 06 Dec '16

06 Dec '16

> > This was due to a bug in the yaml package, apologies. It's been patched, > and the next version of Stack will have the bugfix. I believe the next > version will be released in the next few days, but if you're able to build > from master, you can use that. > Thanks a lot for your answer, it's good to know that soon the new Stack version will solve it. > > Here's the original issue, which includes a link to a temporary workaround: > https://github.com/commercialhaskell/stack/issues/2491 > > I'll take a look at that. > On Mon, Dec 5, 2016 at 8:13 PM, Andre Fernandes <fernand...@gmail.com > <javascript:>> wrote: > >> I am new in Haskell, and I am trying to use stack in my "Windows 10" >> machine to study a little more. >> >> Stack installed nicely, but when I run "stack setup" at the command >> prompt I get the following error: >> >> *"Could not parse 'C:\Users\Andr├®\AppData\Roaming\stack\config.yaml':* >> *InvalidYaml (Just (YamlException "Yaml file not found: >> C:\\Users\\Andr\233\\AppData\\Roaming\\stack\\config.yaml"))* >> >> *See http://docs.haskellstack.org/en/stable/yaml_configuration/ >> <http://docs.haskellstack.org/en/stable/yaml_configuration/>."* >> >> My name is "André" with an accent, and that's the problem, it can not >> find config.yaml at my windows user directory. Is there a way to solve this >> problem, maybe force stack to look into another folder, or something else? >> >> My windows command prompt encoding is 850, I do not not know if this info >> could help. >> >> Thanks in advance for any answer, >> André. >> >> _______________________________________________ >> 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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stack setup errors when user name has accents
by Andre Fernandes 06 Dec '16

06 Dec '16

I am new in Haskell, and I am trying to use stack in my "Windows 10" machine to study a little more. Stack installed nicely, but when I run "stack setup" at the command prompt I get the following error: *"Could not parse 'C:\Users\Andr├®\AppData\Roaming\stack\config.yaml':* *InvalidYaml (Just (YamlException "Yaml file not found: C:\\Users\\Andr\233\\AppData\\Roaming\\stack\\config.yaml"))* *See http://docs.haskellstack.org/en/stable/yaml_configuration/."* My name is "André" with an accent, and that's the problem, it can not find config.yaml at my windows user directory. Is there a way to solve this problem, maybe force stack to look into another folder, or something else? My windows command prompt encoding is 850, I do not not know if this info could help. Thanks in advance for any answer, André.

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Following-up on the laziness thread on Reddit
by Saurabh Nanda 06 Dec '16

06 Dec '16

Thoughts on this particular comment - https://www.reddit.com/r/haskell/comments/5fyg9e/how_important_is_laziness_… - from core GHC hackers would be very interesting and enlightening. -- Saurabh.

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Call for Haskell.org Committee Nominations
by Gershom B 05 Dec '16

05 Dec '16

Dear Haskellers, It is time to put out a call for new nominations (typically but not necessarily self-nominations) to the haskell.org committee. We have four members of our committee due for retirement -- Adam Foltzer, Nicolas Wu, Andres Loeh, and Edward Kmett (who is stepping down early). As per our bylaws, three of the slots will be for regular three year terms, and one will be a short one year term to fill out the remainder of Edward's. To nominate yourself, please send an email to committee at haskell.org by December 2, 2016. The retiring members are eligible to re-nominate themselves. Please feel free to include any information about yourself that you think will help us to make a decision. The Haskell.org committee serves as a board of directors for Haskell.org, a 501(c)3 nonprofit which oversees technical and financial resources related to Haskell community infrastructure. Being a member of the committee does not necessarily require a significant amount of time, but committee members should aim to be responsive during discussions when the committee is called upon to make a decision. Strong leadership, communication, and judgement are very important characteristics for committee members. The role is about setting policy, providing direction/guidance for Haskell.org infrastructure, planning for the long term, and being fiscally responsible with the Haskell.org funds (and donations). As overseers for policy regarding the open source side of Haskell, committee members must also be able to set aside personal or business related bias and make decisions with the good of the open source Haskell community in mind. We seek a broad representation from different segments of the Haskell world -- including but not limited to those focused on education, those focused on industrial applications, those with background in organizing users-groups, and those focused directly on our technical infrastructure. More details about the committee's roles and responsibilities are on https://wiki.haskell.org/Haskell.org_committee If you have any questions about the process, please feel free to e-mail us at committee at haskell.org, or contact one of us individually. Best, Gershom Bazerman

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[course announcement] Haskell for Life
by Sergiu Ivanov 05 Dec '16

05 Dec '16

Dear Haskell Cafe, This year I have taught and will teach a short course introducing people to Haskell. I realised that such a course might interest the subscribers of this list, so here is the course page, with all course materials (CC-BY licence): http://lacl.fr/~sivanov/doku.php?id=en:haskell_for_life Any feedback is welcome. (I will teach the next instance of the course in the following two weeks in Chișinău, Republic of Moldova, so if you happen to be around, don't hesitate to come by and give me a wink IRL ;-) ) -- Sergiu

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