- Haskell-Cafe - Haskell.org

hiring PureScript coder
by Dennis Raddle 17 May '18

17 May '18

Hello list, I'm have many years of Python/C++ programming experience professionally, and I've used Haskell in my hobbies. But I'm now working full time as a math tutor. Every day I get ideas for a web app that could help me teach math, and maybe could eventually be for sale in the app store. I'd like to write version 0.1 of this in PureScript. And because I have more money than time at this point, I'd like to hire someone to get me started. I'm thinking of asking for the following: - set up a PureScript project that integrates with React - write code that demonstrates using the kinds of features I'll need, like React features, the HTML5 canvas, and JavaScript math notation libraries. - be available for a couple of Skype or Hangouts meetings as I look over this and have questions Can I get some suggestions as to where to find willing PureScript programmers, and a ballpark number of hours for this? I mean just an order of magnitude... is this closer to 5 hours, 10 hours, or 50 hours? Thanks, D

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ANNOUNCE: Haskell Communities and Activities Report (34th ed., May 2018)
by Mihai Maruseac 16 May '18

16 May '18

On behalf of all the contributors, we are pleased to announce that the Haskell Communities and Activities Report (34th edition, May 2018) is now available, in PDF and HTML formats: http://haskell.org/communities/05-2018/report.pdf http://haskell.org/communities/05-2018/html/report.html All previous editions of HCAR can be accessed on the wiki at https://wiki.haskell.org/Haskell_Communities_and_Activities_Report Many thanks go to all the people that contributed to this report, both directly, by sending in descriptions, and indirectly, by doing all the interesting things that are reported. We hope you will find it as interesting a read as we did. If you have not encountered the Haskell Communities and Activities Reports before, you may like to know that the first of these reports was published in November 2001. Their goal is to improve the communication between the increasingly diverse groups, projects, and individuals working on, with, or inspired by Haskell. The idea behind these reports is simple: Every six months, a call goes out to all of you enjoying Haskell to contribute brief summaries of your own area of work. Many of you respond (eagerly, unprompted, and sometimes in time for the actual deadline) to the call. The editors collect all the contributions into a single report and feed that back to the community. When we try for the next update, six months from now, you might want to report on your own work, project, research area or group as well. So, please put the following into your diaries now: ======================================== End of September 2018: target deadline for contributions to the October 2018 edition of the HCAR Report ======================================== Unfortunately, many Haskellers working on interesting projects are so busy with their work that they seem to have lost the time to follow the Haskell related mailing lists and newsgroups, and have trouble even finding time to report on their work. If you are a member, user or friend of a project so burdened, please find someone willing to make time to report and ask them to "register" with the editors for a simple e-mail reminder in November (you could point us to them as well, and we can then politely ask if they want to contribute, but it might work better if you do the initial asking). Of course, they will still have to find the ten to fifteen minutes to draw up their report, but maybe we can increase our coverage of all that is going on in the community. Feel free to circulate this announcement further in order to reach people who might otherwise not see it. Enjoy! -- 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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state monad transformer that adds or combines state
by Dennis Raddle 15 May '18

15 May '18

I find myself using the state and exception monads at large scale in my programs. For instance I often keep a pseudorandom generator as the state, and use exception handling. In local computations, I may want to use some additional state. Is there a way to add a little extra state temporarily? Let's say I have data State1 = State1 StdGen type M1 = State State1 data State2 = State2 State1 Int type M2 = State State2 runM2 :: M2 a -> Int -> M1 a someFunc :: M1 Double someFunc = do r <- <compute something pseudorandomly> r2 <- runM2 (deeperFunc r) 3 <..etc..> deeperFunc :: Double -> M2 Double

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template haskell library for OO-like selector syntax?
by Dennis Raddle 15 May '18

15 May '18

In my current application, I'm really missing the ability from OO to do things like someData.field1.field2 = "foo" What's do I mean? - field selectors are scoped so that names don't clash with each other or global names - this way of selecting data can be used both for reading it, and for updating specific fields of some data deep in a data hierarchy (In Haskell, if using immutable data, this would requiring doing a data update on every level). Any attempt to do this in Haskell, for me anyway, results in an explosion of names and a lot of boilerplate code and a resulting heavy syntax. Is there a way of obtaining OO-like concise syntax, perhaps with Template Haskell? Dennis

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Failing build for HaXml
by Vanessa McHale 15 May '18

15 May '18

Does anyone know how to submit patches for HaXml? The .cabal file does not list any upstream source repo and it's currently breaking with GHC 8.4.2, which in turn breaks cabal-debian. Thanks -- *Vanessa McHale* Functional Compiler Engineer | Chicago, IL Website: www.iohk.io <http://iohk.io> Twitter: @vamchale PGP Key ID: 4209B7B5 Input Output <http://iohk.io> Twitter <https://twitter.com/InputOutputHK> Github <https://github.com/input-output-hk> LinkedIn <https://www.linkedin.com/company/input-output-global>

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GHC TV station?
by Sylvester Hazel 15 May '18

15 May '18

White space in "do notation" is no longer supported by GHC but I had to guess it the hard way seeing my solutions to Hutton's book and then his own code produce "Parse error" and irritating hint "Possibly caused by a missing 'do'?". So, Hutton 2ed is outdated, Haskell Platform is dropped exhausted then perhaps GHC should have a TV station? Fun is best when it can be shared. Regards, Sylvester

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Haskell eXchange 2018 CFP (London, Thursday, 11th - Friday, 12th October)
by Oliver Charles 15 May '18

15 May '18

Hi all, The Haskell eXchange is an annual conference created for and by the Skills Matter community. An opportunity for Haskellers to meet, learn and share skills, discover emerging technologies and help evolve the Haskell ecosystem. Everyone is welcome to join, whether you are an expert or a beginner, whether you are a commercial user, an academic or a hobbyist, we'd love it if you join us this year at the Haskell eXchange! For 2018, we are planning to have three types of sessions: 1. Regular talks (35 minutes) 2. Hands-on workshops (approximately 90 minutes) 3. Lightning talks (5-10 minutes to be determined in the formal confirmation) The Haskell eXchange is a broad conference, and we'll consider anything with a clear Haskell connection. For example, talks about Haskell libraries and applications, experience reports of using Haskell for work, and tutorials on programming techniques are all fantastic proposals - but please feel free to submit anything that you think is interesting. The committee are happy to work with you if you're unsure if your talk is a good fit, and can be reached at haskellx(a)skillsmatter.com Most importantly, we're looking for talks that inspire and educate. If your proposal doesn't fit into any of the above categories, it doesn't matter! To submit, please see the form in https://skillsmatter.com/conferences/10237-haskell-exchange-2018#get_involv… We look forward to your submissions!

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Maintaining cpphs
by Markus Ongyerth 15 May '18

15 May '18

Hi Malcolm, Are you still interested in maintaining cpphs? I have posted an issue to your github tracker [1] (linked at [2]) and didn't get any response in a week. While that's not a terribly long time, the reason for this patch is trickling down to different distributions repositories (arch and debian-sid) which is making it harder for me to support users because of a dependency. If you are not planing to maintain cpphs in future, I'd like to take over the package on hackage. Cheers, ongy [1] https://github.com/malcolmwallace/cpphs/issues/16 [2] http://hackage.haskell.org/package/cpphs

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PSA for Cabal 2.2 new-* users regarding .ghc.environment files
by Gershom B 14 May '18

14 May '18

There is an important change in the cabal new- commands for 2.2 that the release docs should have highlighted more significantly. Cabal new-* commands now produce a .ghc.environment file by default. These files [1] are picked up by ghc and ghci automatically (since 8.0.1), and allow them to operate directly with the same package environment used by the new-* commands. This lets you, for example, run `ghci` in a project where you are using `new-build` and get the proper dependencies in scope. Herbert has written an experimental tool to make it easier to create and manipulate these environments [2]. However: there is a drawback (on which some discussion at [3] and [4]. In particular, there is not good information provided by ghc about when these files are picked up and used. So if you are admixing new-* commands and other commands for the time being, jumping between the two, or admixing ghc and ghcjs, etc., then you may run into unexpected behavior! [5] The simplest solution for now is to delete the local .ghc.environment file in those cases (i.e. where you're mixing commands and get unexpected behavior). A particular gotcha is that these files are picked up not just in the current directory but also in any parent directory. Cheers, Gershom [1] documented at https://downloads.haskell.org/~ghc/latest/docs/html/users_guide/packages.ht… [2] https://github.com/hvr/cabal-env [3] https://github.com/haskell/cabal/issues/4542 [4] https://ghc.haskell.org/trac/ghc/ticket/13753 [5] Error messages may be like ".cabal/store/ghc-8.0.2/package.db/package.cache: openBinaryFile: does not exist (No such file or directory)" or complaints about missing inplace dependencies.

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Re: [Haskell-cafe] Problem with submitting papers for haskell 2018
by Nicolas Wu 14 May '18

14 May '18

Hello Winter, Thanks for getting in touch, I’m glad to hear that you’re preparing a submission to the Haskell Symposium this year. You haven’t missed any deadlines: we’re still reviewing the early track papers and so EasyChair is closed for regular submissions until notifications for those papers are released. This will happen on 18 May 2018. Best wishes, Nick Dr Nicolas Wu Department of Computer Science University of Bristol > On 14 May 2018, at 14:19, Brent Yorgey <byorgey(a)gmail.com> wrote: > > Hi Nick, > > Did you see this message that was sent to haskell-cafe a few hours ago? > > -Brent > > ---------- Forwarded message --------- > From: winter <drkoster(a)qq.com> > Date: Mon, May 14, 2018 at 4:15 AM > Subject: [Haskell-cafe] Problem with submitting papers for haskell 2018 > To: <haskell-cafe(a)haskell.org> > > > Dear all, > > Currently i and my friends @sighingnow are writing a paper on our > new I/O manager based on libuv. We planed to submit it to Haskell 2018, > and according to the official site's info, the deadline should be next > month: https://icfp18.sigplan.org/track/haskellsymp-2018-papers > > But here is my problem, i registered an account on easychair as Haskell > 2019 required and logged in, but when i click the submit link, a page > with following info are provided: > > > Paper submission for Haskell 2018 is closed.,,You seem to have no > previous roles at Haskell 2018, so > you cannot enter its pages. If you > have questions about the conference, please contact Haskell 2018 > chairs. > > What does this mean? Did i miss the submission window? Or do i have to > do some extra preparations? Please help! > > > Cheers~ > > Winter > > > > _______________________________________________ > 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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