- Haskell-Cafe - Haskell.org

Minimizing cascading rebuilds
by ☂Josh Chia (謝任中) 30 Mar '18

30 Mar '18

Hi, In my project, I have multiple packages. One of the packages, packageA, is very fundamental and depended on directly and indirectly by almost all the other packages. It has functions that use some hard-coded data (a ByteString top-level variable) also defined within packageA. This hard-coded data is appended regularly, causing packageA to be rebuilt and thus almost all the other packages to be rebuilt, and building takes a painfully long time. I know I can move this hard-coded data to a file that's read at run-time, but that means one more item to plumb in at run-time (where to find the file), and IO (preventing the functions from being pure), so I would like to keep it hard-coded. Is there an elegant way to prevent or minimize the cascading rebuild of the dependent packages just because the hard-coded data in packageA changed? For analogy, in C or C++, source code gets compiled to .o files, one for each .cpp source file. Multiple .o files get linked into executables. So, unless the interface (.hpp files) also change, an implementation (.cpp file) change does not cause dependents to be recompiled to get new .o files, although dependent executables get relinked. I'm not familiar with the compilation and linking logic in GHC so maybe it has additional complications. BTW, I'm using stack, in case it makes any difference to the nature of the problem. Josh

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Haskell to Ethereum VM ?
by Takenobu Tani 30 Mar '18

30 Mar '18

Hi cafe, Does anyone know about the code generator from Haskell's syntax to Ethereum VM language (bytecode)? That is, what corresponds to Solidity in Haskell. Although Solidity is interesting, it's difficult for me to achieve quality and safety. Does such a project already exist? Regards, Takenobu

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Re: [Haskell-cafe] Accelerating Automatic Differentiation
by Michal J Gajda 30 Mar '18

30 Mar '18

Hi Charlie It certainly looks like exciting project, but the bar is currently placed very high. TensorFlow package not only provides automatic differentiation for whole programs, but also optimizes data processing both on GPU, and reading to achieve large batches. This field has a lot of hot developments, so You would either need to propose something unique to Haskell, or You risk being outclassed by PyTorch and TensorFlow bindings Maybe Dominic suggests something too. Cheers Michal

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ANN: network-2.6.3.5
by evan＠evan-borden.com 29 Mar '18

29 Mar '18

Announcing network-2.6.3.5 * Reverting "Do not closeFd within sendFd" [#271](https://github.com/haskell/network/pull/271) Sorry for any disruption this versioning snafu may have caused. https://hackage.haskell.org/package/network-2.6.3.5

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[Call for Contributions] Haskell Communities and Activities Report, May 2018 edition (34th edition)
by Mihai Maruseac 26 Mar '18

26 Mar '18

Dear all, We would like to collect contributions for the 34th edition of the ============================================================ Haskell Communities & Activities Report http://www.haskell.org/haskellwiki/Haskell_Communities_and_Activities_Report Submission deadline: 30 April 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: The usual format is a LaTeX source file, adhering to the template that is available at: http://haskell.org/communities/11-2017/template.tex There is also a LaTeX style file at http://haskell.org/communities/11-2017/hcar.sty that you can use to preview your entry. If you do not know LaTeX or don't want to use it or don't have time to translate your entry into it, then please use plain text, it is better to have an entry in plain-text which we will translate than not have it at all. 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. Please 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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GSoC Mentoring/Voting
by Aloïs Cochard 26 Mar '18

26 Mar '18

Hi all, I'm a bit confuse about the process regarding voting on GSoC proposals and proposing as mentor. I receive email from Google that seems to talk about a UI that I have never seen (i.e. they speak about some purple button "I want to be mentor"), OTOH there is this GitHub repository where it seems people contributed proposals. It seems like tomorrow is the deadline for the proposal, so I'm curious what will be the next steps for potential mentor as it seems we diverged a bit from the "official Google way". Thanks for the help. -- *Λ\oïs* http://twitter.com/aloiscochard http://github.com/aloiscochard

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GSoC Project Introduction: Accelerate Automatic Differentiation
by Charles Blake 26 Mar '18

26 Mar '18

Dear all, I'm a student interested in the GSoC programme and I wanted to introduce myself and make contact with those involved in potentially mentoring for the 'Implementing Automatic Differentiation in Accelerate' project (https://summer.haskell.org/ideas.html#accelerate-automatic-differentiation) If it would be more appropriate for me to contact those individuals directly then please let me know. My name is Charlie Blake, and I'm currently coming to the end of my CS undergrad degree. Much of my study of late has been focused on functional programming and parallelism - so when I saw this project proposal it jumped out at me! I was expecting to be assisting research at my university (St Andrews University, Scotland) in this field over the summer, but this arrangement has recently fallen through. Hence why I'm unfortunately sending this message rather close to the deadline. Nevertheless, I'm now hoping very much to get on the GSoC program, to which I am very much committed. With regards to the project itself, I'm currently in the process of drawing up a proposal. Although I'm making every effort to read as much as I can about the 'ad' and 'accelerate' libraries, it's still quite hard to get a good sense of the scope of the project. Would, for instance, it be a reasonable goal to expect to be able to implement all of the core 'ad' functionality in my own parallel library in the time-frame? This seems like the natural objective, but I don't want to propose an unrealistically large project if this is not feasible. If anyone has answers to these questions and might further be willing to discuss a draft project proposal with me over the next few days that would be greatly appreciated. Many thanks, Charlie Blake

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Munich Haskell Meeting, 2018-03-28 @ 19:30
by Christian Neukirchen 26 Mar '18

26 Mar '18

Dear all, Next week, our monthly Munich Haskell Meeting will take place again on Wednesday, March 28 at Cafe Puck at 19h30. For details see here: http://muenchen.haskell.bayern/dates.html If you plan to join, please add yourself to this dudle so we can reserve enough seats! It is OK to add yourself to the dudle anonymously or pseudonymously. https://dudle.inf.tu-dresden.de/haskell-munich-mar-2018/ Everybody is welcome! cu, -- Christian Neukirchen <chneukirchen(a)gmail.com> http://chneukirchen.org

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[ANN] brittany-0.9.0.0 (on both hackage&stackage)
by lennart spitzner 26 Mar '18

26 Mar '18

- Implement `IndentPolicyLeft`: A layouting setting that disables "hanging indentation". This indentation mode may become default in the future. Only configurable via config-file for the time being. - (!) commandline interface is reworked slightly to support multiple inputs/outputs (`brittany --write-mode=inplace *.hs`). This removes the --input/--output flags. - Ensure compatibility with stackage - Change default global config path (old configs are still respected) - Improve support for per-project config - Fix several bugs and Improve language extension support full changelog at https://hackage.haskell.org/package/brittany-0.9.0.0/changelog brittany was recently added to stackage, and should hopefully be included in the next LTS release. -- lennart

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GSoC Haddock project
by Quentin Liu 25 Mar '18

25 Mar '18

Hi all, I am Qingbo Liu, a cs student from Colby College, ME. I’m very interested in the Hi Haddock project and would like to work on it for the summer. Currently I have finished a draft proposal and I am revising it (Thank Alex Biehl here for his kind suggestions). If the project would help you and you are willing to spend some time improving the proposal, please take a look at [1]. Any comment is appreciated. [1] https://docs.google.com/document/d/1BcSeLu8X9QwiM5LzYq5UEU5jIFF7hogdDT3UByU… Best Regards, Qingbo Liu

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