News aggregator

Mobile Development

haskell-cafe - Fri, 05/27/2016 - 1:42pm
I'm wondering if anyone has any experience they can share, know of any blog posts or anything else documenting the use of Haskell when developing a mobile application. Ideally, I would like something along the lines of having a native UI, a language bridge, and use Haskell for the core logic. My main focus would be getting this to work on Android and iOS. If this would also work on Blackberry and Windows Phone it would be a plus. I have successfully done this using C++ in place of Haskell in the past, but would really be interested in getting something working using Haskell. Thanks, Justin _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe< at >haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/haskell-cafe
Categories: Offsite Discussion

Hackage (partially) down?

haskell-cafe - Fri, 05/27/2016 - 5:40am
Hi all, I'm getting Error 503 Connection timed out Connection timed out Guru Mediation: Details: cache-ams4123-AMS 1464323906 827600523 Varnish cache server when trying to browse Hackage this morning. Anyone else having the same problem? (downforeveryoneorjustme.com says that "it's just me", so I'm guessing this is some sort of CDN issue?) Regards,
Categories: Offsite Discussion

Pattern synonyms and GADTs in GHC 8.0.1

glasgow-user - Thu, 05/26/2016 - 4:27pm
I have a problem where a pattern synonym doesn't provide the expected type refinement in GHC 8.0.1. This gives the error • No instance for (Eq a) arising from a pattern Possible fix: add (Eq a) to the context of the type signature for: simplifyP :: Exp a -> Exp a • In the pattern: AddP a (NumP 0) In an equation for ‘simplifyP’: simplifyP (AddP a (NumP 0)) = a If I remove the type signature for `AddP`, the code goes through. Unfortunately, in my real code I need the type signature in order to resolve overloading. GHC 7.10 didn't have this problem. Is this a bug? / Emil
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CFP: Workshop on Type-driven Development (TyDe '16)

General haskell list - Thu, 05/26/2016 - 12:13pm
-------------------------------------------------------------------------------- FINAL CALL FOR PAPERS 1st Type-Driven Development (TyDe '16) A Workshop on Dependently Typed and Generic Programming 18 September, Nara, Japan -------------------------------------------------------------------------------- The deadline of the inaugural edition of TyDe is approaching rapidly. Please submit full papers before June 10th and abstracts before June 24th. # Goals of the workshop The workshop on Type-Driven Development aims to show how static type information may be used effectively in the development of computer programs. The workshop, co-located with ICFP, unifies two workshops: the Workshop on Dependently Typed Programming and the Workshop on Generic Programming. These two research areas have a rich history and bridge both theory and practice. Novel techniques explored by both commun
Categories: Incoming News

Example of FunBind without wrapping AbsBind?

haskell-cafe - Wed, 05/25/2016 - 5:41pm
I was playing with the AST's typechecked tree, and found some examples of the subject, but can't tell what is the rule for that to occur. It was a local binding. Do you have a hint and/or a minimal example? Thanks! Robin _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe< at >haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/haskell-cafe
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Cannot install 8.0.1 from bindist

glasgow-user - Wed, 05/25/2016 - 12:55pm
Trying to install ghc-8.0.1-x86_64-centos67-linux.tar.xz with: ./configure --prefix={prefix} make install-strip gives me an error. The tail of the log is: Registering ghc-8.0.1... for f in '{prefix}/lib/ghc-8.0.1/package.conf.d'/*; do create () { touch "$1" && chmod 644 "$1" ; } && create "$f"; done /usr/bin/install -c -m 755 -d "{prefix}/bin" for i in utils/hp2ps/dist/build/tmp/hp2ps; do \ /usr/bin/install -c -m 755 -s $i "{prefix}/bin" ; \ done /usr/bin/install -c -m 755 -d "{prefix}/lib/ghc-8.0.1/bin" for i in inplace/lib/bin/ghc-split; do \ /usr/bin/install -c -m 755 $i "{prefix}/lib/ghc-8.0.1/bin"; \ done /usr/bin/install -c -m 755 -d "{prefix}/share/doc/ghc-8.0.1" /usr/bin/install -c -m 755 -d "{prefix}/share/doc/ghc-8.0.1/html" /usr/bin/install -c -m 644 docs/index.html "{prefix}/share/doc/ghc-8.0.1/html" /usr/bin/install -c -m 755 -d "{prefix}/share/doc/ghc-8.0.1/html/libraries" for i in libraries/dist-haddock/*; do \ /usr/bin/install -c -m 644 $i "{prefix}/share/doc/ghc-8.0.1/htm
Categories: Offsite Discussion

1st CfP: IFL 2016 (28th Symposium on Implementation and Application of Functional Languages)

General haskell list - Tue, 05/24/2016 - 8:13pm
Hello, Please, find below the first call for papers for IFL 2016. Please forward these to anyone you think may be interested. Apologies for any duplicates you may receive. best regards, Jurriaan Hage Publicity Chair of IFL --- IFL 2016 - Call for papers 28th SYMPOSIUM ON IMPLEMENTATION AND APPLICATION OF FUNCTIONAL LANGUAGES - IFL 2016 KU Leuven, Belgium In cooperation with ACM SIGPLAN August 31 - September 2, 2016 https://dtai.cs.kuleuven.be/events/ifl2016/ Scope The goal of the IFL symposia is to bring together researchers actively engaged in the implementation and application of functional and function-based programming languages. IFL 2016 will be a venue for researchers to present and discuss new ideas and concepts, work in progress, and publication-ripe results related to the implementation and application of functional languages and function-based programming. Peer-review Following the IFL tradition, IFL 2016 will use a post-symposium review process
Categories: Incoming News

1st CfP: IFL 2016 (28th Symposium on Implementation and Application of Functional Languages)

haskell-cafe - Tue, 05/24/2016 - 8:13pm
Hello, Please, find below the first call for papers for IFL 2016. Please forward these to anyone you think may be interested. Apologies for any duplicates you may receive. best regards, Jurriaan Hage Publicity Chair of IFL --- IFL 2016 - Call for papers 28th SYMPOSIUM ON IMPLEMENTATION AND APPLICATION OF FUNCTIONAL LANGUAGES - IFL 2016 KU Leuven, Belgium In cooperation with ACM SIGPLAN August 31 - September 2, 2016 https://dtai.cs.kuleuven.be/events/ifl2016/ Scope The goal of the IFL symposia is to bring together researchers actively engaged in the implementation and application of functional and function-based programming languages. IFL 2016 will be a venue for researchers to present and discuss new ideas and concepts, work in progress, and publication-ripe results related to the implementation and application of functional languages and function-based programming. Peer-review Following the IFL tradition, IFL 2016 will use a post-symposium review process
Categories: Offsite Discussion

A Java bytecode interpreter written in Haskell

haskell-cafe - Tue, 05/24/2016 - 6:43pm
(Please keep expectations low for now; this is just a weekend project.) I have written, in Haskell, something that aspires to be a Java Virtual Machine (but I don't call it a JVM yet as it doesn't fully comply with the spec). The code is available here: https://github.com/edom/haji This is similar to Frege [3], but while Frege aims to run a variant of Haskell on Java, this project tries the other direction: running a subset of Java on Haskell. Thanks. Best, Erik Some related stuffs: [1] https://github.com/MateVM/MateVM [2] https://hackage.haskell.org/package/hs-java [3] https://github.com/Frege/frege [4] https://wiki.haskell.org/GHC:FAQ#Why_isn.27t_GHC_available_for_.NET_or_on_the_JVM.3F [5] https://github.com/levans/Open-Quark
Categories: Offsite Discussion

Dev/tools/git/Haskell role in London

haskell-cafe - Tue, 05/24/2016 - 5:12pm
https://donsbot.wordpress.com/2016/05/24/haskell-devtoolsgit-role-at-standard-chartered-london/ I have a new role at SCB this time in the "Modelling Infrastructure" team to work on our Haskell-based continuous integration and testing system on top of git. This is a London role. More details in the linked post. _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe< at >haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/haskell-cafe
Categories: Offsite Discussion

GHC 8.0.1 Compile time regression + Trac ticketprivileges

haskell-cafe - Tue, 05/24/2016 - 1:36pm
[x-post from Reddit reply] Thanks so much for all the hard work! Unfortunately I have a compile time performance regression to report on my FLTKHS <https://github.com/deech/fltkhs> library. I also don't have a minimal example. There is a demo that took about 15 seconds compile and link in 7.10.3, but with no changes now takes over a minute in 8.0.1. I've reproduced this across machines and operating systems. Since there was interest expressed in using this example as a benchmark if any GHC devs are still willing to help, I'm willing to walk them through getting the library set up etc. It's not a long process. The tip of my Github branch has been updated to build with GHC 8.0.1. I made myself a Trac account but apparently I don't have Ticket privileges so it won't let me create one. My username is 'deech'. Thanks! -deech _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe< at >haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/haskell-cafe
Categories: Offsite Discussion

Stack build with GHC 8?

haskell-cafe - Tue, 05/24/2016 - 9:10am
Hi, My name appears in the Stackage GHC 8 mega-issue [ https://github.com/fpco/stackage/issues/1476] and I'd like to upgrade my packages. I suspect it's just a case of relaxing the upper bound on base to <4.10 but I'd quite like to check that this does, in fact, work. However I'm not sure how to go about doing this since there don't yet seem to be any stackage snapshots that use GHC 8. What's the best way to get around this? Cheers, David _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe< at >haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/haskell-cafe
Categories: Offsite Discussion

CFP: ACM MobiWac 2015 - November 13 - 17, 2016, Malta

General haskell list - Mon, 05/23/2016 - 7:16pm
** We apologize if you receive multiple copies of this message ** ================================================================== The 14th ACM International Symposium on Mobility Management and Wireless Access (MobiWac 2016) (in conjunction with the 19th ACM MSWiM) November 13 - 17, 2016 - Malta http://mobiwac-symposium.org/ ================================================================== The 14th ACM International Symposium on Mobility Management and Wireless Access (MobiWac 2016) will be held in conjunction with MSWiM 2016 (the 19th ACM International Symposium on Modeling, Analysis and Simulation of Wireless and Mobile Systems) from November 13 to 17, 2016 in Malta. The MOBIWAC series of events are intended to provide an international forum for the discussion and presentation of original ideas, recent results and achievements by research
Categories: Incoming News

Call for papers: 21th International Conference on Engineering of Complex Computer Systems (ICECCS 2016), Dubai, United Arab Emirates, November 6-8 2016

General haskell list - Mon, 05/23/2016 - 12:28pm
21th International Conference on Engineering of Complex Computer Systems (ICECCS 2016) || November 6-8, Dubai, United Arab Emirates || http://www.aston.ac.uk/eas/about-eas/academic-groups/computer-science/iceccs-2016/ Overview --------------------- Over the past several years, we have seen a rapid rising emphasis on design, implement and manage complex computer systems to help us deal with an increasingly volatile, globalised complex world. These systems are critical for dealing with the Grand Challenge problems we are facing in the 21st century, including health care, urbanization, education, energy, finance, and job creation. The complex computer systems are frequently distributed over heterogeneous networks and processing large amount data. Performance, real-time behavior, fault tolerance, security, adaptability, development time and cost, long life concerns are the key issues. The goal of this conference is to bring together industrial, academic, and government experts, from a variety of user domains
Categories: Incoming News

Help moving a bounds check into a case branch

haskell-cafe - Mon, 05/23/2016 - 4:27am
Sorry for the terrible subject line, but I'm a but stuck here. A couple days ago I overhauled Data.Sequence.splitAt, greatly improving its performance. You can see the new implementation at https://github.com/haskell/containers/blob/e8b1f664a631e3795dfd14f2d8c2b39c906284cf/Data/Sequence.hs#L2346 . There's one spot where I'm still stuck, however. Much like the original implementation, I check that the splitting index is before the end of the sequence (to ensure correctness). I go further, in fact, checking that the splitting index is positive, in order to avoid allocating a new tree-top in a trivial split. Logically, this check should be moved into the Deep case branch in splitTreeE, to avoid pattern matching on the top of the tree twice and performing redundant comparisons. However, when I make that move, the split/append benchmark gets worse. When I looked at the Core, it seemed that I confused GHC somehow. I ended up with a join point taking an extra argument that it totally ignored. I can fix that bench
Categories: Offsite Discussion

Representation of 3-D objects in non-continuous space

haskell-cafe - Sun, 05/22/2016 - 6:57pm
I've been poking at the problem that I've talked about in the following threads. https://groups.google.com/forum/#!searchin/haskell-cafe/michael$20litchard|sort:date/haskell-cafe/n0Tc29UUgoQ/iitt3z3PCwAJ https://groups.google.com/forum/#!searchin/haskell-cafe/michael$20litchard|sort:date/haskell-cafe/qD2kaZ9qpEA/jTDAp8KoCgAJ And my misguided conclusions here https://groups.google.com/forum/#!topic/haskell-cafe/PMtYhVQ5nNQ I'm trying to write a clone in haskell of the space-system implemented in http://swmud.org. The biggest error in my thinking so far is assuming I could do without spatial extent. Nope, these objects in space will have to have spatial extent. So no octree for me. The advice and comments from the first two threads prompted me to investigate R-trees. I could only find specifics about how to describe 2-D. Until I found this paper on layered R-Trees. http://www.isprs.org/proceedings/XXXIII/congress/part4/1216_XXXIII-part4.pdf This looks like what I want. Here's my re-formulation of the c
Categories: Offsite Discussion

Going insane over overlapping instances

haskell-cafe - Sun, 05/22/2016 - 6:05pm
This is driving me nuts. So I have a type class HasStructParser I've defined. Details are irrelevant except that if you have HasStructParser defined, then ToJSON is also defined. So I have: instance HasStructParser s => ToJSON s where ... But now, any type that defines ToJSON any other way causes an Overlapping Instances error to happen- the conflict being between the real ToJSON implementation and the one deriving from HasStructParser- this despite the fact that there is no implementation for HasStructParser for the given type. Now, I don't want to allow Overlapping Instances because if there are *real* overlapping instances, I want that to be an error. For instance, if a structure did implement HasStructParser and some other implementation of ToJSON, I want to know. I suppose I could go: newtype JSON a = JSON a instance HasStructParser s => ToJSON (JSON s) where ... But this strikes me as being ugly- now I have to add pointless JSON constructors everywhere I want to convert to
Categories: Offsite Discussion

ANNOUNCE: testbench-0.1.0.0

haskell-cafe - Sun, 05/22/2016 - 3:23pm
I've just released a new library onto Hackage that aims to help you writing comparison-oriented benchmarks by: a) reducing the duplication found when using criterion directly b) let you test your benchmarked values/functions to ensure that they have the same result/satisfy a given predicate c) provide more comparison-oriented output I've written more about it here: https://ivanmiljenovic.wordpress.com/2016/05/23/test-your-benchmarks/ Or you could go straight to the Hackage page here: http://hackage.haskell.org/package/testbench
Categories: Offsite Discussion

Interacting with Java in GHCVM

haskell-cafe - Sun, 05/22/2016 - 3:54am
Hi Haskell-Cafe, I've been working on a JVM backend for GHC [1] and I took some time to flesh out a design for the Java FFI [2] which will pretty much decide whether the project will be useful or not. I would love feedback from the community on how to improve the design or requests for important interop features that I have neglected. Thanks, Rahul Muttineni [1] http://github.com/rahulmutt/ghcvm [2] https://gist.github.com/rahulmutt/355505bce57c7c2cffd7d4cf5edddad4 _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe< at >haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/haskell-cafe
Categories: Offsite Discussion

Haskell Meetup group in Delhi, India

haskell-cafe - Sat, 05/21/2016 - 7:44am
Hi all, I just started a meetup group for Haskellers in and around Delhi NCR, India. The plan is to organise regular (monthly) meetups, talks, workshops etc for Haskell / FP enthusiasts at all skill levels. Anyone interested is welcome to join at - http://meetu.ps/c/2K4ft/FT8H/f. Also, since we are just getting started, the best way to help right now would be to spread the word! Thanks, Anupam Jain
Categories: Offsite Discussion