News aggregator

Amazon SES email issues

haskell-cafe - Fri, 04/29/2016 - 7:45am
Hi everyone, I'm having issues with sending email through Amazon SES. I'm using the *Network.Mail.Mime.SES* package. The error I get is: *email-test-exe: SESException {seStatus = Status {statusCode = 403, statusMessage = "Forbidden"}, seCode = "SignatureDoesNotMatch", seMessage = "The request signature we calculated does not match the signature you provided. Check your AWS Secret Access Key and signing method. Consult the service documentation for details.", seRequestId = "8ceb250a-0dd3-11e6-892c-4fb1a14d4732"}* What's confusing is that I'm using the same SES settings in a Rails app as well as a small Rust console program without any issues (it works from the same machine too). The only thing I can think of is that with this Haskell package, I haven't found where to set certain things like the port number (587) and so maybe it's that? Here is a small sample app that illustrates the problem. What am I missing? Thanks. *{-# LANGUAGE OverloadedStrings #-}{-# LANGUAGE QuasiQuotes #-}* *module Main where*
Categories: Offsite Discussion

[ANN] Pre-announcing ZuriHac 2016

haskell-cafe - Thu, 04/28/2016 - 10:42pm
Hello fellow Haskellers, it's my pleasure to announce that this year's ZuriHac, the Zurich Haskell hackathon, will happen from July 22nd to 24th. The registration will open this Saturday at 12pm (UTC+2). More information will follow. Greetings, Alex on behalf of the orga team _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe< at >haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/haskell-cafe
Categories: Offsite Discussion

ANN: Haskell Prime 2020 committee has formed

General haskell list - Thu, 04/28/2016 - 8:29pm
Dear Haskell Community! Some time ago I asked for nominations to reboot the Haskell Prime process[1], and now I'm pleased to finally announce the formation of the new Haskell Language 2020 Committee! The goal of the Haskell Language committee together with the Core Libraries Committee is to work towards a new Haskell 2020 Language Report. I'd like to remind everyone that the Haskell Prime Process[4] relies on *everyone* in the community to help by contributing proposals which the committee will then evaluate and if suitable help formalise for inclusion. Everyone interested in participating is also invited to join the haskell-prime mailing list. Four years (or rather ~3.5 years) from now may seem like a long time. However, given the magnitude of the task at hand, to discuss, formalise, and implement proposed extensions (taking into account the recently enacted three-release-policy[3]) to the Haskell Report, the process shouldn't be rushed. Consequently, this may even turn out to be a tight schedule after
Categories: Incoming News

ANN: Haskell Prime 2020 committee has formed

libraries list - Thu, 04/28/2016 - 10:57am
Dear Haskell Community! Some time ago I asked for nominations to reboot the Haskell Prime process[1], and now I'm pleased to finally announce the formation of the new Haskell Language 2020 Committee! The goal of the Haskell Language committee together with the Core Libraries Committee is to work towards a new Haskell 2020 Language Report. I'd like to remind everyone that the Haskell Prime Process[4] relies on *everyone* in the community to help by contributing proposals which the committee will then evaluate and if suitable help formalise for inclusion. Everyone interested in participating is also invited to join the haskell-prime mailing list. Four years (or rather ~3.5 years) from now may seem like a long time. However, given the magnitude of the task at hand, to discuss, formalise, and implement proposed extensions (taking into account the recently enacted three-release-policy[3]) to the Haskell Report, the process shouldn't be rushed. Consequently, this may even turn out to be a tight schedule after
Categories: Offsite Discussion

[ANNOUNCE] GHC 8.0.1 release candidate 4 available

glasgow-user - Thu, 04/28/2016 - 10:10am
Hello Haskellers, The GHC team is happy to announce the availability of fourth release candidate of the Glasgow Haskell Compiler's 8.0.1 release. Source and binary distributions can be found at, http://downloads.haskell.org/~ghc/8.0.1-rc4/ This is the last of four candidates leading up to the 8.0.1 release, addressing nearly all of the known issues of the previous candidates. These include, * A type-checker panic triggered by use of Typeable on a kind-polymorphic type constructor (#11334) * A type-checker explosion where -XTypeInType would gobble up massive amounts of memory when used in a data instance (#11407) * A variety of other typechecker issues (#11811, #11797, #11813, #11814) * A build issue seen on OS X (#11828) * Template Haskell can now produce instances with OVERLAPP{ING,ABLE,ED} pragmas * Autoconf has improved version checks for libdw (#11820) * Typeable and hs-boot files now interact nicely (#11824) * The build system now checks for the broken App
Categories: Offsite Discussion

Summer of Haskell - Now Accepting Applications!

haskell-cafe - Wed, 04/27/2016 - 10:10pm
(Note: I am posting this on behalf of Edward Kmett who has spotty availability at the moment) We've posted an official Summer of Haskell website: https://summer.haskell.org/ It contains the full timeline for the program this summer, and most importantly, a form for submitting student applications, also linked here: https://docs.google.com/forms/d/1JLIa58u7AcWN31bH_LcCBujN9uzAwfd3HxrT32qz9_g/viewform The student application period ends next Friday, May 6. Last year we had a very successful project brainstorming thread. This led to our largest and most successful Summer of Code, ever. There is a thread on reddit now devoted to the purpose of further brainstorming for this year: https://www.reddit.com/r/haskell/comments/4gh1tu/summer_of_haskell_now_accepting_applications/ If you have a proposal that you think a student could make a good dent in over the course of a summer, especially one with broad impact on the community, please feel free to discuss it there. If you are a potential student, please fe
Categories: Offsite Discussion

Hackage package index download failure

haskell-cafe - Wed, 04/27/2016 - 8:21pm
I'm unable to download the package index file used by cabal: $ cabal update Downloading the latest package list from hackage.haskell.org cabal: Failed to download http://hackage.haskell.org/packages/archive/00-index.tar.gz : ErrorMisc "Error HTTP code: 502" A few hours ago the error was a 503. Anybody know what's going on? Regards, Sean _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe< at >haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/haskell-cafe
Categories: Offsite Discussion

wren gayle romano: Hacking projects over the next few months

Planet Haskell - Wed, 04/27/2016 - 4:08pm

Life’s been really hectic lately, but I’ve been getting (slowly) back into working on my Haskell packages. In particular, since the switch from darcs to github I’ve started getting more comments and feature requests, which is nice. Over the next half-year or so, here’s what I’ll be up to in my free time between work on the dissertation and work on Hakaru:

containers — I’ve been appointed one of the new co-maintainers of our favorite venerable library. I prolly won’t be doing any major work until autumn (as mentioned when I was appointed), but I’ve had a number of conversations with David Feuer about where to take things in terms of cleaning up some old maintenance cruft.

bytestring-trie — A few years back I started reimplementing my tries to use Bagwell’s Array Mapped Tries in lieu of Okasaki’s Big-Endian Patricia Tries, but then got stalled because life. I’ve started up on it again, and it’s just about ready to be released after a few more tweaks. Also, now that I’m working on it again I can finally clear out the backlog of API requests (sorry folks!).

exact-combinatorics — A user recently pointed me towards a new fast implementation of factorial making waves lately. It’s not clear just yet whether it’ll be faster than the current implementation, but should be easy enough to get going and run some benchmarks.

unification-fd — This one isn’t hacking so much as dissemination. I have a backlog of queries about why things are the way they are, which I need to address; and I’ve been meaning to continue the tutorial about how to use this library for your unification needs.

logfloat — We’ve been using this a lot in Hakaru, and there are a few performance tweaks I think I can add. The main optimization area is trying to minimize the conditionals for detecting edge cases. The biggest issue has just been coming up with some decent benchmarks. The problem, of course, is that most programs making use of logfloats do a lot of other work too so it can be tricky to detect the actual effect of changes. I think this is something Hakaru can help a lot with since it makes it easy to construct all sorts of new models.



comments
Categories: Offsite Blogs

Fw: Bikeshedding request for GHCi's :type

haskell-cafe - Wed, 04/27/2016 - 1:34pm
Dear cafe, I'm forwarding mail from ghc-devs ML [1]. I think `:type` command is very important for beginners and middle users. Please feedback your opinion to them ;) [1]: https://mail.haskell.org/pipermail/ghc-devs/2016-April/011933.html next year and shuddered at having to teach Foldable at the same time as `length`. So I implemented feature request #10963 ( https://ghc.haskell.org/trac/ghc/ticket/10963), which allows for a way for a user to request a specialization of a type. It all works wonderfully, but there is a real user-facing design issue here around the default behavior of :type and whether or not to add new :type-y like commands. I have outlined the situation here: https://ghc.haskell.org/trac/ghc/wiki/Design/GHCi/Type this all works, please skim that wiki page and comment on #10963. Cheers, Takenobu _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe< at >haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/haskell-cafe
Categories: Offsite Discussion

Chez Scheme now open-source

Lambda the Ultimate - Wed, 04/27/2016 - 11:32am

Kent Dybvig (Cadence Research, Cisco Systems) has released the commercial scheme compiler Chez Scheme (scheme.com) as open source on GitHub. Chez Scheme is a native code generating optimizing compiler for R6RS focusing on performance and productivity. It supports cross-compilation, threading, and many other extensions. Current version is 9.4.

I'm excited to see what the community will build with this great tool.

https://github.com/cisco/chezscheme

Categories: Offsite Discussion

Discussion: reconsider lens-like exports from containers

libraries list - Tue, 04/26/2016 - 8:03pm
Way back when, Shachaf Ben-Kiki suggested an efficient implementation of `at` for Data.Map in https://mail.haskell.org/pipermail/libraries/2013-May/019761.html but that was never approved for inclusion. I believe I've come up with a somewhat nasty but efficient implementation of `ix` for Data.Sequence (hand-specialized and hand-unboxed), based on the code for `adjust`. See https://gist.github.com/treeowl/b80c2c490563765fc7881be30f3dba24 lens has continued to grow in popularity, so I think the time has probably come to talk again about adding `at` for Data.Map, and to talk about adding `ix` for Data.Sequence. Note: for consistency with the rest of the Data.Sequence API, `ix` would be named `adjustA`, and would have its first two arguments flipped. David Feuer
Categories: Offsite Discussion

Proposal: Add rtsIsThreaded to base

libraries list - Tue, 04/26/2016 - 1:36pm
I would propose adding a Bool value to base that indicates whether the code was compiled/linked with the threaded or single threaded runtime system. A library might want to implement certain functionality differently depending on whether the threaded runtime system is used (i.e. avoid blocking C FFI calls in single-threaded). There is currently no good way to do this. StackExchange currently suggests using "Control.Concurrent.rtsSupportsBoundThreads" for this, which is defined as: HsBool rtsSupportsBoundThreads(void) { #if defined(THREADED_RTS) return HS_BOOL_TRUE; #else return HS_BOOL_FALSE; #endif } But it seems undesirable to conflate support for bound threads and use of the threaded runtime system? Especially since this would be a trivial addition to Control.Concurrent (i.e. simply an ifdef'ed True/False constant). Cheers, Merijn _______________________________________________ Libraries mailing list Libraries< at >haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/libraries
Categories: Offsite Discussion

[ANN] Erlang Workshop 2016 - CFP

General haskell list - Tue, 04/26/2016 - 10:45am
Apologies for any duplicates you may receive. CALL FOR PAPERS =============== Fifteenth ACM SIGPLAN Erlang Workshop ------------------------------ ----------------------------- Nara, Japan, September 23, 2016 Satellite event of the 21st ACM SIGPLAN International Conference on Functional Programming (ICFP 2016) September 18-24, 2016 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
Categories: Incoming News

Magic classes for Overloaded Record Fields, overlaps, FunDeps

glasgow-user - Tue, 04/26/2016 - 9:20am
There's an intriguing comment here wrt anonymous records: https://ghc.haskell.org/trac/ghc/wiki/Records/OverloadedRecordFields/ MagicClasses#Designextension:anonymousrecords (End of the section) "... this doesn't quite work, because the two instances overlap, but it is possible with a bit more trickery" I could well understand if everybody's forgotten what was the "trickery", because ORF has been so long in the pipeline, but could anyone explain? Reason for the q: I'm looking at anonymous records myself, including extending, shortening and joining anon records. And yes overlapping instances are everywhere. Using type families isn't being too ergonomic. And I notice ORF has used FunDeps. But for me, FunDeps in the HList style is also rather ugly. Is there some trickery I'm missing? Thanks AntC
Categories: Offsite Discussion

When using Cereal, what is the right way to write `get` for multi-constructor type?

haskell-cafe - Tue, 04/26/2016 - 6:39am
Hi, Say I have code already like: data STH = A | B | C instance Serialize STH where put A = putWord8 1 put B = putWord8 66 put C = putWord8 111 Then what is the better way to do `get`? Is following the only one? get = do i <- getWord8 case i of 1 -> return A 66 -> return B 111 -> return C Thanks. _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe< at >haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/haskell-cafe
Categories: Offsite Discussion

Cabal extensions tracking

haskell-cafe - Tue, 04/26/2016 - 1:46am
It's possible to enable extensions using an "extensions" field in a Cabal file, in which case Cabal will be able to report what language extensions the package requires. Unfortunately, this can be confusing, since the extensions in effect do not appear at the top of each affected module. Is there any way to get Cabal to report required extensions *based on LANGUAGE pragmas*? David
Categories: Offsite Discussion

Chris Smith: CodeWorld & Summer of Haskell 2016

Planet Haskell - Mon, 04/25/2016 - 11:24pm

As most Haskell community members know, Haskell was turned down by Google Summer of Code this year, and has instead been seeking to continue the tradition with Summer of Haskell, funded by smaller donations. I’m happy to announce that CodeWorld will be part of Summer of Haskell! I’ve donated to support one student working specifically on CodeWorld.

Are you a student, and interested in helping to build a platform for education in expressive mathematics and computer science? Want to work on a project with immediate impact teaching Haskell in multiple schools?  Please propose a project at https://summer.haskell.org/ between now and May 6th.

Project Ideas

A great source of CodeWorld project ideas is the bug tracker.  Less well-defined projects are tagged as proposals, while more defined features are tagged as enhancements.  A few big ones to think about are:

  • Export of CodeWorld projects as mobile applications
  • Better and more language-aware editor support for Haskell in CodeMirror.
  • Implementing constructive geometry
  • Building social, gallery, and/or showcase features to help student work be more visible.
  • Building a purely functional block-based programming environment.
  • Implementing visual tools to help students understand substitution, list comprehensions, and more.

I look forward to working with someone this summer building something cool!

By the way, HUGE thanks to Edward Kmett and other Haskell.org committee members for making this happen this year!


Categories: Offsite Blogs

Postdoc ad: Domain-specific languages

General haskell list - Mon, 04/25/2016 - 9:35pm
The Programming Language Group at Tufts University seeks applicants for a postdoctoral position on a new project that will focus on building tools to construct first-class embedded Domain-Specific Language. As computing has taken on a larger role in many areas of science, there is an increasing need to provide experts in those domains with effective programming tools. Domain-specific programming languages (DSLs) are appealing because they allow domain experts to write programs using familiar concepts and abstractions. The problem is that implementing a new programming language -- including all the expected support tools, such as editors, type checkers, compilers, profilers, and debuggers -- is a substantial undertaking. The goal of this project is to develop a system for building embedded domain-specific languages, including the full chain of support tools. Embedded DSLs (EDLSs) are convenient for language designers because they can inherit the infrastructure of the host language: syntax, type system, libr
Categories: Incoming News

Interactive ASCII graphics

haskell-cafe - Mon, 04/25/2016 - 6:43pm
Gary Fixler recently gave a talk, to the Santa Monica Haskell Users Group at Brainium, in which he creates an interactive explorer for (among other images) the Mandelbrot set, using nothing but text. No complex libraries for graphics or reactivity are involved -- the only foreign import statements are to Data.Monoid, Data.Function, Data.Complex, and System.IO. The code is here: https://github.com/gfixler/continou This gif demonstrates it: http://www.garyfixler.com/2016-04-18-012037_3840x1024_scrot.gif The video is here: https://vimeo.com/163287967/99e0595942
Categories: Offsite Discussion

Munich Haskell Meeting, 2016-04-28 < at > 19:30

haskell-cafe - Mon, 04/25/2016 - 1:47pm
Dear all, This week, our monthly Munich Haskell Meeting will take place again on Thursday, April 28 at Cafe Puck at 19h30. For details see here: http://chneukirchen.github.io/haskell-munich.de/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-apr-2016/ Everybody is welcome! cu,
Categories: Offsite Discussion