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Fwd: 2nd Call for Papers: 16th ACM SIGPLAN Erlang Workshop 2017
by Rob Stewart 24 Apr '17

24 Apr '17

2nd CALL FOR PAPERS =============== Sixteenth ACM SIGPLAN Erlang Workshop http://erlang.org/workshop/2017/ ----------------------------------------------------------- Oxford, United Kingdom, 8 September 2017 Satellite event of the 22nd ACM SIGPLAN International Conference on Functional Programming (ICFP 2017) 3 - 9 September, 2017 The Erlang Workshop aims to bring together the open source, academic, and industrial communities of Erlang, to discuss technologies and languages related to Erlang. The Erlang model of concurrent programming has been widely emulated, for example by Akka in Scala, and even new programming languages were designed atop of the Erlang VM, such as Elixir. Therefore we would like to broaden the scope of the workshop to include systems like those mentioned above. The workshop will enable participants to familiarize themselves with recent developments on new techniques and tools, novel applications, draw lessons from users' experiences and identify research problems and common areas relevant to the practice of Erlang, Erlang-like languages, functional programming, distribution, concurrency etc. We invite three types of submissions. 1. Technical papers describing language extensions, critical discussions of the status quo, formal semantics of language constructs, program analysis and transformation, virtual machine extensions and compilation techniques, implementations and interfaces of Erlang in/with other languages, and new tools (profilers, tracers, debuggers, testing frameworks, etc.). The maximum length for technical papers is restricted to 12 pages. 2. Practice and application papers describing uses of Erlang in the "real-world", Erlang libraries for specific tasks, experiences from using Erlang in specific application domains, reusable programming idioms and elegant new ways of using Erlang to approach or solve a particular problem. The maximum length for the practice and application papers is restricted to 12 pages. Note that this is a maximum length; we welcome shorter papers also, and the program committee will evaluate all papers on an equal basis independent of their lengths. 3. Poster presentations describing topics related to the workshop goals. Each includes a maximum of 2 pages of the abstract and summary. Presentations in this category will be given an hour of shared simultaneous demonstration time. Workshop Co-Chairs ------------------ Scott Lystig Fritchie, VMware, USA Natalia Chechina, Glasgow University, UK Program Committee ----------------------------- (Note: the Workshop Co-Chairs are also committee members) Clara Benac Earle, Universidad Politecnica de Madrid, Spain Richard Carlsson, Klarna, Sweden Laura M. Castro, University of A Coruna, Spain Viktoria Fördős, Klarna, Sweden James S. Larson, Google, USA Important Dates ----------------------- Submission deadline: Fri May 26, 2017 Author notification: Fri June 23, 2017 Final submission for the publisher: Sat July 15, 2017 Workshop date: Fri September 8, 2017 Instructions to authors -------------------------------- Papers must be submitted online via EasyChair (via the "Erlang2017" event). The submission page is https://www.easychair.org/conferences/?conf=erlang2017 Submitted papers should be in portable document format (PDF), formatted using the ACM SIGPLAN style guidelines. Each submission must adhere to SIGPLAN's republication policy. Violation risks summary rejection of the offending submission. Accepted papers will be published by the ACM and will appear in the ACM Digital Library. The proceedings will be freely available for download from the ACM Digital Library from one week before the start of the conference until two weeks after the conference. Paper submissions will be considered for poster submission in the case they are not accepted as full papers. Venue & Registration Details ------------------------------------------ For registration, please see the ICFP 2017 web site at: http://icfp17.sigplan.org/ Related Links -------------------- ICFP 2017 web site: http://icfp17.sigplan.org/ Past ACM SIGPLAN Erlang workshops: http://www.erlang.org/workshop/ Open Source Erlang: http://www.erlang.org/ EasyChair submission site: https://www.easychair.org/conferences/?conf=erlang2017 Author Information for SIGPLAN Conferences: http://www.sigplan.org/authorInformation.htm Atendee Information for SIGPLAN Events: http://www.sigplan.org/Resources/Policies/CodeOfConduct/

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Looking for a new stackage curator
by Adam Bergmark 24 Apr '17

24 Apr '17

Hi everyone, We are looking to expand the stackage curator team again! Please see this document for more information: https://github.com/fpco/stackage/blob/master/become-a-curator.md If you are already convinced you can go straight to https://goo.gl/forms/eD6lTLtuyyHAIcfC2 Re-applications are encouraged! Cheers, Adam

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Dynamic Programming exercises
by Michael Litchard 23 Apr '17

23 Apr '17

I found the below link to be an illuminating read in regards to how to approach dynamic programming in haskell. Now I would like to test my understanding on different exercises. I'd like suggestions on problems that could be solved by the approach elucidated below. http://jelv.is/blog/Lazy-Dynamic-Programming/

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What does the "S" in "ShowS" signify?
by Chris Martin 22 Apr '17

22 Apr '17

The name "ShowS" in Text.Show always been mysterious to me. Can anyone explain why it's called that?

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Vacancy: Functional Software Engineer
by Damian Nadales 21 Apr '17

21 Apr '17

Hello Cafe, I'm forwarding a job opening in Eindhoven, The Netherlands. """ We are looking for an experienced software developer with good GUI development skills. Proven knowledge on the principles and working of build, test and release management through experience with several tools is required. Part of the work will be in choosing an appropriate GUI build framework catering for the different partner environments. The Model Driven Development Tool is implemented in Haskell. However, no specific Haskell knowledge is required, but hands on experience with a modern functional language is. Please contact Koen.Schilders(a)enter-group.nl """ Best regards, Damian.

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Wow Monads!
by David McClain 21 Apr '17

21 Apr '17

It’s been about 15 years on/off since I first looked at Monads. This weekend I finally sat down and really learned what they are, how they work. I found what looks like the seminal paper on them by Phil Wadler: https://page.mi.fu-berlin.de/scravy/realworldhaskell/materialien/the-essenc… <https://page.mi.fu-berlin.de/scravy/realworldhaskell/materialien/the-essenc…> I’m a pretty heavy Common Lisp guy, going on 30 years with it. I also did tons of SML and OCaml programming. But I only dipped my toe into Haskell a few times. What I was looking for was a more in-depth understanding of Monads and how they work. I remember reading that Wadler paper many years ago, and I was intrigued by the conciseness of changing the interpreter to do different instrumentation. I was hoping to find a magic bullet like that for my Lisp code. And I noticed that Lisp almost never makes any mention of Monads. Surely there is a benefit that could be had… Anyone else have Lisp experience using Monads? Did it offer some major enhancements for you? - DM

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Why does `mzip /= liftM2 (,)`
by Mateusz Kowalczyk 21 Apr '17

21 Apr '17

Hi, Today after half a decade I have found `MonadZip` in `base`. The laws state: ``` liftM (f *** g) (mzip ma mb) = mzip (liftM f ma) (liftM g mb) liftM (const ()) ma = liftM (const ()) mb ==> munzip (mzip ma mb) = (ma, mb) ``` The question is why does ``` mzip /= liftM2 (,) ``` in plain words. Notably we can see lack of IO instance which I'm guessing has something to do asynchronous exceptions but I'm probably wrong…. Rather than investigating for next 30 minutes, I thought I'd just sample existing knowledge (that I could not find out from Google). In what circumstances can we not replace `liftM2 (,)` with `mzip`? -- Mateusz K.

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Problem with tuple with one element constrained
by Tyson Whitehead 20 Apr '17

20 Apr '17

I've been unable to get the following (simplified) code to be accepted by GHCi (8.0.1 and 8.0.2) Prelude> let (x, y) = (1, return 2) <interactive>:1:5: error: • Could not deduce (Monad m0) from the context: Num t bound by the inferred type for ‘x’: Num t => t at <interactive>:1:5-24 The type variable ‘m0’ is ambiguous • When checking that the inferred type x :: forall a (m :: * -> *) t. (Num a, Num t, Monad m) => t is as general as its inferred signature x :: forall t. Num t => t and I don't seem to be able to provide a type signatures that GHCi is okay with Prelude> let { x :: Int; y :: Monad m => m Int; (x, y) = (1, return 2) } <interactive>:5:40: error: • Ambiguous type variable ‘m0’ prevents the constraint ‘(Monad m0)’ from being solved. • When checking that the inferred type x :: forall a (m :: * -> *) t (m1 :: * -> *). (Num a, Num t, Monad m) => t is as general as its signature x :: Int Prelude> let (x, y) = (1, return 2) :: (Int, Monad m => m Int) <interactive>:4:31: error: • Illegal qualified type: Monad m => m Int GHC doesn't yet support impredicative polymorphism • In an expression type signature: (Int, Monad m => m Int) In the expression: (1, return 2) :: (Int, Monad m => m Int) In a pattern binding: (x, y) = (1, return 2) :: (Int, Monad m => m Int) Prelude> let (x,y) = (1,return 2) :: Monad m => (Int, m Int) <interactive>:7:5: error: • Ambiguous type variable ‘m0’ prevents the constraint ‘(Monad m0)’ from being solved. • When checking that the inferred type x :: forall (m :: * -> *). Monad m => Int is as general as its inferred signature x :: Int It seems the constraint on y leaks to x where it isn't well formed? Any help and/or explanations would be greatly appreciated. In my actual code the assignment is from the return value of a function so I can't just split it into two separate statements. Thanks! -Tyson

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Re: [Haskell-cafe] Problem with tuple with one element constrained
by Tyson Whitehead 20 Apr '17

20 Apr '17

On Tue, Apr 18, 2017, 16:02 Joshua Grosso <jgrosso1(a)asu.edu <mailto:jgrosso1@asu.edu>> wrote: /If/ I'm understanding correctly, GHCI's complaining about the fact that `return 2` requires it to create an instance of a `Monad`, but it doesn't know which `Monad` instance it should use... Does `let (x, y) = (1, return 2) :: (Int, Maybe Int)` work (where you can replace `Maybe` with any other monad)? Hi Joshua, Thanks for the input. You are correct that if I choose a particular Monad instance GHCi accepts the code. I believe it should be able to do the assignment without choosing one though. It is, for example, okay with let y = return 2. I'm thinking Sergiu is onto something about this having to do with special GHCi handling. Thanks! -Tyson

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Re: [Haskell-cafe] Haskell 2020: 'let' to be optional and with wider scope of visibility, like other Haskell functions
by Doug McIlroy 20 Apr '17

20 Apr '17

> It's just helping clean up a bit words that doesn't have much meaning. > Currently GHCi in GHC 8 is supporting this, so you could write both: > > x = 10 > x <- return 10 > > Which is great! I trust that "x = 10" above does NOT t mean the same as "let x = 10". If it did, then it wouldn't mean what it does in Haskell. Then code tried successfully in GHCI could fail in GHC. Compare this GHCI session > let x = 10 > :t x x :: Num a => a > x + 0.0 10.0 to this, in which x = 10 has its Haskell meaning > :! cat test.hs x = 10 > :load test.hs > :t x x :: Integer > x + 0.0 No instance for (Fractional Integer) arising from the literal ‘0.0’. Doug

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