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[Call for Contributions] Haskell Communities and Activities Report, November 2018 edition (35th edition)
by Mihai Maruseac 06 Oct '18

06 Oct '18

Dear all, We would like to collect contributions for the 35th edition of the ============================================================ Haskell Communities & Activities Report http://www.haskell.org/haskellwiki/Haskell_Communities_and_Activities_Report Submission deadline: 4 November 2018 (please send your contributions to hcar at haskell.org, in plain text or LaTeX format, both are equally accepted) ============================================================ This is the short story: * If you are working on any project that is in some way related to Haskell, please write a short entry and submit it. Even if the project is very small or unfinished or you think it is not important enough --- please reconsider and submit an entry anyway! * If you are interested in an existing project related to Haskell that has not previously been mentioned in the HCAR, please tell us, so that we can contact the project leaders and ask them to submit an entry. * If you are working on a project that is looking for contributors, please write a short entry and submit it, mentioning that your are looking for contributors. * Feel free to pass on this call for contributions to others that might be interested. More detailed information: The Haskell Communities & Activities Report is a bi-annual overview of the state of Haskell as well as Haskell-related projects over the last, and possibly the upcoming six months. If you have only recently been exposed to Haskell, it might be a good idea to browse the previous edition --- you will find interesting projects described as well as several starting points and links that may provide answers to many questions. Contributions will be collected until the submission deadline. They will then be compiled into a coherent report that is published online as soon as it is ready. As always, this is a great opportunity to update your webpages, make new releases, announce or even start new projects, or to talk about developments you want every Haskeller to know about! Looking forward to your contributions, Mihai Maruseac FAQ: Q: What format should I write in? A: Any format is ok, I will transpose the submission to the format in use at the time of publication. Previous editions have used a LaTeX format, with the template that is available at: http://haskell.org/communities/11-2018/template.tex And the associated LaTeX style file at http://haskell.org/communities/11-2018/hcar.sty You can use those to edit and preview your entry, but it is very likely that by the time of publication the entire HCAR pipeline would be changed to a more modern one. You will receive a copy of the draft, prior to publication, to ensure that everything looks ok. If you modify an old entry that you have written for an earlier edition of the report, you should soon receive your old entry as a template (provided we have your valid email address). Please modify that template, rather than using your own version of the old entry as a template. Q: Can I include Haskell code? A: Yes. If using LaTeX, you can use lhs2tex syntax (http://www.andres-loeh.de/lhs2tex/) The report is compiled in mode polycode.fmt. Q: Can I include images? A: Yes, you are even encouraged to do so. Please use .jpg or .png format, then. PNG is preferred for simplicity. Q: Should I send files in .zip archives or similar? A: No, plain file attachments are the way. Q: How much should I write? A: Authors are asked to limit entries to about one column of text. A general introduction is helpful. Apart from that, you should focus on recent or upcoming developments. Pointers to online content can be given for more comprehensive or "historic" overviews of a project. Images do not count towards the length limit, so you may want to use this opportunity to pep up entries. There is no minimum length of an entry! The report aims for being as complete as possible, so please consider writing an entry, even if it is only a few lines long. Q: Which topics are relevant? A: All topics which are related to Haskell in some way are relevant. We usually had reports from users of Haskell (private, academic, or commercial), from authors or contributors to projects related to Haskell, from people working on the Haskell language, libraries, on language extensions or variants. We also like reports about distributions of Haskell software, Haskell infrastructure, books and tutorials on Haskell. Reports on past and upcoming events related to Haskell are also relevant. Finally, there might be new topics we do not even think about. As a rule of thumb: if in doubt, then it probably is relevant and has a place in the HCAR. You can also simply ask us. Q: Is unfinished work relevant? Are ideas for projects relevant? A: Yes! You can use the HCAR to talk about projects you are currently working on. You can use it to look for other developers that might help you. You can use HCAR to ask for more contributors to your project, it is a good way to gain visibility and traction. Q: If I do not update my entry, but want to keep it in the report, what should I do? A: Tell us that there are no changes. The old entry will typically be reused in this case, but it might be dropped if it is older than a year, to give more room and more attention to projects that change a lot. Do not resend complete entries if you have not changed them. Q: Will I get confirmation if I send an entry? How do I know whether my email has even reached its destination, and not ended up in a spam folder? A: Prior to publication of the final report, we will send a draft to all contributors, for possible corrections. So if you do not hear from us within two weeks after the deadline, it is safer to send another mail and check whether your first one was received. -- Mihai Maruseac (MM) "If you can't solve a problem, then there's an easier problem you can solve: find it." -- George Polya

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Which pretty print library?
by waldmann 04 Oct '18

04 Oct '18

Dear Cafe, what is today's answer to this old question: https://stackoverflow.com/questions/9761507/which-pretty-print-library In particular, I agree with author's: "The thing that worries me about these [many pretty-printing libraries] is that many of them have many releases. This implies they've had features added, bugs fixed, etc. But have they all had the same bugs fixed?" Meanwhile, there's https://hackage.haskell.org/package/prettyprinter "This package solves all these issues, and then some." (clearly an instance of https://xkcd.com/927/ ) GHC is using pretty-1.1.3.6 ? - J.W.

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[JOB] Haskell job opportunity at RELEX Solutions in Helsinki, Finland
by Mats Rauhala 02 Oct '18

02 Oct '18

Would you like to get paid for writing Haskell? And do you live in Europe, preferably in Helsinki, Finland? If yes, please read on. RELEX Solutions is Europe's fastest growing provider of integrated retail and supply chain planning solutions. We are looking for a few Haskell developers to join our small, but impactful group of Haskellers to develop our internal tools. In this position you will be exposed to various technologies, such as Haskell, Servant, Elm, GHCJS, Terraform, Ansible, Nix, RHEL/CentOS, AWS etc. Your own interests are influential in what your daily work will consist of. Your main responsiblities will be some mix of development, operations and support of and around our coordination system. Interested in applying? Follow the link: https://relex.recruiterbox.com/jobs/fk01gjr/ Full remote for this position is negotiable, but you should be able to be present at the Helsinki office at least for a couple of weeks, preferably longer. Details of your contract are largely negotiable. Please note that the available position will be filled as soon as suitable candidates are found, so don't wait too long ;). I'm also available for questions: - 'masser' at functionalprogramming slack - 'MasseR' at freenode - 'mats.rauhala(a)gmail.com' email or on this mailing list. -- Mats Rauhala

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Internship at Tsuru
by Mikhail Baykov 02 Oct '18

02 Oct '18

Hi Cafe Tsuru Capital is looking for interns. Haskell knowledge is required, experience with pricing futures/options would be nice but not necessary. Located in Tokyo, company language is English. Casual environment, nice monitors and a big coffee machine. Duration 3-4 months, starting at your convenience. We will help you with visa and looking for a place to stay. There's some salary. Details how to apply are on our website. https://www.reddit.com/r/haskell/comments/9knxtu/tsuru_is_looking_for_more_… Feel free to ask questions here, in email or #tsurucapital on freenode.

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Natural Deduction
by Yasuaki Kudo 02 Oct '18

02 Oct '18

Hi, I have already sent similar questions to other forums but am still looking. Would you please advise where I can find a good explanation of Natural Deduction? I have been reading the link below so far. http://www.cs.cmu.edu/~fp/courses/atp/handouts/ch2-natded.pdf Cheers! Yasu

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ANN: hledger-1.11 released
by Simon Michael 01 Oct '18

01 Oct '18

Short announcement this quarter. Pleased to announce the release of hledger 1.11 on schedule! Thanks to release contributors Joseph Weston, Dmitry Astapov, Gaith Hallak, Jakub Zárybnický, Luca Molteni, and SpicyCat. stack users will need to get a copy of hledger source and do stack install from there, due to the recent GHC 8.6 release. cabal install hledger-1.11 should work normally. From http://hledger.org/release-notes.html#hledger-1.11 <http://hledger.org/release-notes.html#hledger-1.11> : hledger 1.11 The default display order of accounts is now influenced by the order of account directives. Accounts declared by account directives are displayed first (top-most), in declaration order, followed by undeclared accounts in alphabetical order. Numeric account codes are no longer used, and are ignored and considered deprecated. So if your accounts are displaying in a weird order after upgrading, and you want them alphabetical like before, just sort your account directives alphabetically. Account sorting (by name, by declaration, by amount) is now more robust and supported consistently by all commands (accounts, balance, bs..) in all modes (tree & flat, tabular & non-tabular). close: new –opening/–closing flags to print only the opening or closing transaction files: a new command to list included files prices: query arguments are now supported. Prices can be filtered by date, and postings providing transaction prices can also be filtered. rewrite: help clarifies relation to print –auto (#745) roi: a new command to compute return on investment, based on hledger-irr test: has more verbose output, more informative failure messages, and no longer tries to read the journal csv: We use a more robust CSV lib (cassava) and now support non-comma separators, eg –separator ‘;’ (experimental, this flag will probably become a CSV rule) (#829) csv: interpolated field names in values are now properly case insensitive, so this works: fields …,Transaction_Date,… date %Transaction_Date journal: D (default commodity) directives no longer break multiplier amounts in transaction modifiers (AKA automated postings) (#860) journal: “Automated Postings” have been renamed to “Transaction Modifiers”. journal: transaction comments in transaction modifier rules are now parsed correctly. (#745) journal: when include files form a cycle, we give an error instead of hanging. upper-case day/month names in period expressions no longer give an error (#847, #852)

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Status of Cloud Haskell
by Alejandro Serrano Mena 28 Sep '18

28 Sep '18

Dear Café, I was wondering what is the current status of Cloud Haskell. Their website only mentions things until 2016, but I see that the 'distributed-process' library is itself well-maintained. It Cloud Haskell still the way to go for distributed processes in Haskell? Regards, Alejandro

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Where is "minimumsBy"?
by Tom Ellis 28 Sep '18

28 Sep '18

Data.List.minimumBy :: Foldable t => (a -> a -> Ordering) -> t a -> a https://www.stackage.org/haddock/lts-12.1/base-4.11.1.0/Data-List.html#v:mi… but there are many cases where that's quite unhelpful. Actually what we want is more like minimumsBy :: ... => (a -> a -> Ordering) -> t a -> [a] There can be many distinct minimizers. For example when I want to get the collection of the youngest people from [(Age, Person)] I want minimumsBy (compare `on` fst) [(12, alice), (15, balaji), (12, cho)] to return [(12, alice), (12, cho)] Does "minimumsBy" exist somewhere reasonably standard? Hoogle doesn't throw up anything obvious https://www.stackage.org/lts-12.1/hoogle?q=%28a+-%3E+a+-%3E+Ordering%29+-%3… Thanks, Tom

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Suppress re-exported module's docs ...
by aditya siram 27 Sep '18

27 Sep '18

Is there any way to have Haddock ignore a re-exported module without hiding it? eg. here all of `B`'s exports/docs show up in `A`'s Haddock page and I don't want to see them there: module A ( ... module B ) import B ...

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Re: [Haskell-cafe] clonetype
by Oleg Grenrus 26 Sep '18

26 Sep '18

The problem is that "All instances" is hard to pin point. We have open world assumption, so instances can be added later (in the dependency tree). Should they be cloned too? And even of you restrict to "instances visible at clonetype definition", that's IMHO not a good idea either, as it's implicit and volatile set (editing imports changes may change the set). So use either tagged-trick/pattern or GND. Haskell's heavy type machinery exists so we can explicitly and exactly say what we need or want. Tagged/phantom-pattern and GND are different, they have different pros & cons. Having `clonetype-fits-all` seems non-trivial to me. Sent from my iPhone > On 24 Sep 2018, at 15.25, Harendra Kumar <harendra.kumar(a)gmail.com> wrote: > > That comes close, but Haskell having such a heavy type machinery to do all the esoteric type stuff in the world, but not allowing you to express such a simple day to day programming thing in a simpler manner is not very satisfying. > > -harendra > >> On Mon, 24 Sep 2018 at 16:16, Oleg Grenrus <oleg.grenrus(a)iki.fi> wrote: >> data MyStringTag >> type MyString = Tagged MyStringTag String >> >> Sent from my iPhone >> >>> On 24 Sep 2018, at 13.42, Harendra Kumar <harendra.kumar(a)gmail.com> wrote: >>> >>> Often, we need to create a newtype that is equivalent to a given type for safety reasons. Using type synonym is useless from type safety perspective. With newtype, we have to add a "deriving" clause to it for deriving the required instances, to make it practically useful. >>> >>> Does it make sense, and is it possible to have something like a "clonetype" that creates a new type and derives all the instances of the parent type as well? It will be quite helpful in creating equivalent newtype synonyms quickly. Almost always, I do not use a newtype where I should just because of the inconvenience of deriving the instances. Ideally, we should just be able to say something like: >>> >>> clonetype MyString = String >>> >>> and we are good to go. What is the shortest possible way to achieve this with currently available mechanisms, if any? >>> >>> -harendra >>> _______________________________________________ >>> 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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