November 2022 - Haskell-Cafe

How to create a list of each constructor value
by PICCA Frederic-Emmanuel 03 Dec '22

03 Dec '22

Hello, I have a type like this data InputType = CristalK6C | MarsFlyscan | MarsSbs | SixsFlyMedH | SixsFlyMedV | SixsFlyMedVEiger | SixsFlyMedVS70 | SixsFlyScanUhv | SixsFlyScanUhv2 | SixsFlyScanUhvTest | SixsFlyScanUhvUfxc | SixsSbsFixedDetector | SixsSbsMedH | SixsSbsMedV | SixsSbsMedVFixDetector deriving (Eq, Show) I want to create a list of each values in order to create meaningfull error message for the user and simplify my Arbitrary instances. I do not want to type two time the values. instance Arbitrary InputType where arbitrary = oneof (map pure [ CristalK6C , MarsFlyscan , MarsSbs , SixsFlyMedH , SixsFlyMedV , SixsFlyMedVEiger , SixsFlyMedVS70 , SixsFlyScanUhv , SixsFlyScanUhv2 , SixsFlyScanUhvTest , SixsFlyScanUhvUfxc , SixsSbsFixedDetector , SixsSbsMedH , SixsSbsMedV , SixsSbsMedVFixDetector ] ) Thanks for your help Frederic

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Debugging a test suite freeze
by David Feuer 01 Dec '22

01 Dec '22

The logict-sequence test suite consistently freezes up on the last test when compiled with GHC 9.4.3. logict-sequence and its test suite don't do anything special with that GHC/base version as far as I can see, or anything particularly strange in general, so I'm pretty confident the problem lies elsewhere. My best guesses are hedgehog, tasty, and tasty-hedgehog. Has anyone else run into weird issues with any/all of these on GHC 9.4.3? David

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FOSDEM Haskell devroom: we need proposals!
by Fraser Tweedale 30 Nov '22

30 Nov '22

Previously: https://mail.haskell.org/pipermail/haskell-cafe/2022-November/135674.html **We need more proposals! We need your help!** FOSDEM 2023 will be held on 4 & 5 February 2023, in Brussels. For more information see the [official site](https://fosdem.org/2023/). The Haskell devroom (specialist track) will take place on Sunday 5 February, from 13:10 to 17:00 UTC+1. This is an amazing opportunity to promote Haskell, and functional programming generally, to a legion of free software developers and enthusiasts. But right now, we are not even close to filling our schedule. If we don't fill our ~4 hour schedule, the Haskell devroom will not happen. Therefore we are extending our Call for Proposals until Saturday 2022-12-10. We are also now welcoming proposals for tutorials/workshops and longer presentations (up to 45 minutes). Shorter presentations are still welcome, of course. So if you want to propose an introductory workshop, install fest, hack session, or something similar, have at it. You can also help by sharing our CFP far and wide, and encourage specific people you think might have something interesting to present, to submit a proposal. Thanks, Fraser Tweedale

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Call for Haskell.org Committee Nominations
by Ida Bzowska 29 Nov '22

29 Nov '22

Dear Haskellers, The Haskell.org Committee is happy to announce that we are opening the call for nominations for new members. Details can be found [here <https://discourse.haskell.org/t/call-for-haskell-org-committee-nominations-…> ]. You can nominate yourself or your friend! If you have any questions, don't hesitate to ask. λCheers Ida Bzowska

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Writing and testing a Storable instance for a record wrapping ForeignPtrs
by Hécate 29 Nov '22

29 Nov '22

Hi everyone, In a fit of madness I have found myself writing Haskell code where I need to implement a Storable instance. However, by virtue of not being a C programmer, I'm fairly lost on some of the details, especially the value of the sizeOf and alignment methods. My Haskell-level record is the following: data SignedMessage = SignedMessage { messageLength :: CSize , messageForeignPtr :: ForeignPtr CUChar , signatureForeignPtr :: ForeignPtr CUChar } Here is the code of the Storable instance: https://gist.github.com/Kleidukos/31346d067f309f2a86cbd97a85c0f1e8#file-sig… And so I used `hedgehog-classes` to test the Storable instance. However, all the tests fail with the same reason: Prelude.undefined: https://gist.github.com/Kleidukos/31346d067f309f2a86cbd97a85c0f1e8#file-und… The main problem (and that's certainly a red herring for me) is that the `undefined` call comes frombase:Foreign.Marshal.Array. Which shouldn't be a problem, as it is not supposed to be evaluated! Yet apparently it is. If you're interested to see the full code, it's located here: https://github.com/haskell-cryptography/libsodium-bindings/blob/add-sel-pac… I'm not sure how to proceed from here. What would be a good angle to approach this? Cheers, Hécate -- Hécate ✨ 🐦: @TechnoEmpress IRC: Hecate WWW: https://glitchbra.in RUN: BSD

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PhD and post-doc positions in Mainz, Germany
by Erdweg, Sebastian 25 Nov '22

25 Nov '22

We have multiple open positions for PhD students and post-docs in the PL Group of the University of Mainz in Germany. The available positions include a gross monthly salary of ~4000 Euro. Our team meets and socializes in Mainz; remote work is an option. The PL Group at the University of Mainz was founded in 2019. Our goal is to support developers in creating and maintaining software systems that are easier to write, more secure, run faster, and consume less energy. Our current research topics include: -- Incremental computing: How can a computation react to a change of its input efficiently? We have observed up to 10,000x speedups in prior work, can incrementality help us save as much energy? Can we build a new foundation for incremental computing to support a wider range of computations? -- WebAssembly: How can we discover and prevent security vulnerabilities in WebAssembly? We have built a data-flow analysis platform for WebAssembly to identify properties of WebAssembly programs at compile time. Can this platform be used to protect WebAssembly users while also optimizing the code for performance? -- Datalog: How can the power of Datalog best be exploited in modern software development? How can we abstract over and hide the technicalities of Datalog, for example, by compiling DSLs to Datalog. And how can we optimize Datalog code to provide truly declarative performance, without exposing users to details of the underlying database technology? -- Language engineering: How can we build programming-language tools with modest effort and without duplicating the language's semantics? For example, can we derive type checkers, debuggers, and other editor services from the language’s semantics? And does this require a language workbench or can we support rich services for embedded languages as well? Mainz is part of the Frankfurt Metropolitan Area and only a short train ride away from Frankfurt's international community and culture. Mainz itself lies at the confluence of the Rhine and Main rivers, surrounded by plenty of nature. https://mainz.de/en/worth-seeing/reasons-to-love-mainz.php I'm excited to hear from interested candidates via email. If you know potential candidates, please forward this message to them. Sebastian Erdweg https://www.pl.informatik.uni-mainz.de/erdweg

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Munich Haskell Meeting, 2022-11-30 @ 19:30
by Leah Neukirchen 25 Nov '22

25 Nov '22

Dear all, Next week, our last* monthly Munich Haskell Meeting of the year 2022 will take place again on Wednesday, November 30 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 nuudel so we can reserve enough seats! It is OK to add yourself to the nuudel anonymously or pseudonymously. https://nuudel.digitalcourage.de/haskell-munich-nov-2022 Everybody is welcome! *) There will be no meeting in late December due to festivities, but perhaps again in the first week of January, as is tradition. cu, -- Leah Neukirchen <leah(a)vuxu.org> https://leahneukirchen.org/

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Learn Physics with Funtional Programming
by Jonathan Drews 23 Nov '22

23 Nov '22

I got the No starch Press *.pdf book "Learn Physics with Functional Programming" by Scott Walck. It's an easy introduction to coding physics problems in Haskell. It is very well written. I mention it because right now, the week of Thanksgiving, NoStarch Press is having a 35% off sale on all books. -- Kind regards, Jonathan

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KSF Media Ab hiring Senior Developer in Helsinki, Finland
by Kari Pahula 23 Nov '22

23 Nov '22

KSF Media is Finland's largest Swedish language news media group. Our products include Hufvudstadsbladet, Västra Nyland, Östnyland and HBL Junior. KSF Media's digital products are growing fast and our focus is in digital subscription sales and product development. We are now looking for a new member to join our digital development team to create outstanding news media products for our readers. We are a small but capable team with a lean way of working and passion to learn new things every day. Our way of working Kanban Pair Programming, Code Reviews Git, CI/CD (multiple deployments a day), Trunk Based Development Working in the open. Our whole frontend is open source: https://github.com/KSF-Media/affresco and https://github.com/KSF-Media/mosaico Our stack Most new developments happen in Haskell, PureScript and Javascript Cloud Infrastructure as Code (Google Cloud, Kubernetes, Terraform) Microservices environment with REST APIs What we expect from you some relevant work experience and English language. Swedish or Finnish knowledge is a plus Knowledge of the principles behind the modern Web stack: things like MVC, Relational Databases and Testing High motivation, self-steering, willingness to learn and dive into things, good social skills and good sense of humour Interest in functional programming, news media and making the world a better place Awareness of some UX principles, API design (and optionally UI design) and empathy for the users of your code What we can offer Flexible terms, with possibility to remote working Competitive salary and benefits The best co-workers Office in the most central location in Helsinki Interested? Please apply via LinkedIn, https://www.linkedin.com/jobs/view/3373101222 or drop a line at antti.haarala(a)ksfmedia.fi no later than on the 5th of December. Reddit discussion at https://www.reddit.com/r/haskell/comments/z2pupj/ksf_media_ab_hiring_senior…

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Upcoming maintenance on Haskell services
by Bryan Richter 22 Nov '22

22 Nov '22

Hello folks, On Thursday 24 November at 6 AM UTC, I will start a 4-hour maintenance window for the following Haskell services: 1. downloads.haskell.org 2. gitlab.haskell.org In particular, I expect the following outages: 1. downloads.haskell.org will be read-only for the duration of the window. * No uploads 2. gitlab.haskell.org will be read-only for the duration of the window. * No CI pipelines(!) * No git pushes * No commenting on issues or merge requests 3. gitlab.haskell.org will furthermore be entirely inaccessible very briefly. * There will be 1-2 outages. * Each outage will last a few seconds. The reason for the maintenance is that our hosting sponsor, Equinix Metal, is performing a facilities migration. One of our servers, gitlab-storage, is slated for retirement. All data and services that run on that server must be moved to a new server. I'm sending this first notification to a wide audience as an extra precaution in case something goes wrong. :) In reality, I expect this maintenance to only affect GHC developers and a small group of ecosystem maintainers. In particular, web access of https://downloads.haskell.org should *not* be affected by this maintenance. I will send further updates to a smaller audience. Note: The actual migration will be quick. Most of the maintenance window will be spent waiting for DNS propagation. -Bryan Haskell Foundation DevOps

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