News aggregator

Hackage update, part 4

Haskell on Reddit - Wed, 09/03/2014 - 5:13am
Categories: Incoming News

HTTP package - supported GHC versions

libraries list - Tue, 09/02/2014 - 10:24pm
Hi, The HTTP package supports a whole load of old GHCs - the current version should actually work with GHC 6.10. For future releases I plan to drop most of these. Any opinions about how far back it should support? I'm thinking restricting it to either 7.4+ or 7.6+, but I'm open to keeping support for older versions too if there's a real need. Cheers, Ganesh
Categories: Offsite Discussion

Functional dependency failure

haskell-cafe - Tue, 09/02/2014 - 9:45pm
Hi! I have following code: STRead.hs: import Control.Monad.Reader import Control.Monad.ST import qualified Data.Vector.Mutable as MV import qualified Data.Vector as V type ReadVecMonad s = ReaderT (MV.MVector s Int) (ST s) freezeV :: ReadVecMonad s (V.Vector Int) freezeV = ask >>= lift V.freeze Trying to compile this I have "Couldn't match type ... When using functional dependencies to combine" error following with kind mismatch and type with literaly the same type mismatch. How can I work this around? There's full error message: STRead.hs:9:11: Couldn't match type `V.MVector s Int' with `(->) (V.MVector (Control.Monad.Primitive.PrimState (ReaderT (V.MVector s Int) (ST s))) Int)' When using functional dependencies to combine MonadReader r (ReaderT r m), arising from the dependency `m -> r' in the instance declaration in `Control.Monad.Rea
Categories: Offsite Discussion

Compose to avoid lambdas?

Haskell on Reddit - Tue, 09/02/2014 - 7:34pm

Is it possible to use fmap and other composition operators to avoid a lambda in something like the following?

filter (\x -> mod x 5 == 0) [0,3,5,13,25]

submitted by stupidquest
[link] [33 comments]
Categories: Incoming News

IntelliJ IDEA haskell-idea-plugin + Hasklig

Haskell on Reddit - Tue, 09/02/2014 - 5:27pm

I've come across this new plugin that makes writing Haskell in IntelliJ IDEA possible: haskell-idea-plugin. It seems to work nice so far, this makes me very happy, kudos to the authors.

But IDEA's editor doesn't seem to work with Hasklig, probably support for ligatures is missing or something... All text (including the symbols) looks just like plain Source Code Pro font.

So is there a way to make it work? Or some other way to make symbols commonly used in Haskell look nice, like candy in Leksah or that thing in Emacs?

Also if you can compare haskell-idea-plugin with the other IDEA plugin HaskForce, I would be interested in your experience.

I hope this is the right place for these kind of questions. Thank you for the answers.

submitted by sideEffffECt
[link] [3 comments]
Categories: Incoming News

ETAPS 2015 2nd call for papers

General haskell list - Tue, 09/02/2014 - 11:32am
****************************************************************** CALL FOR PAPERS: ETAPS 2015 18th European Joint Conferences on Theory And Practice of Software London, UK, 11-18 April 2015 http://www.etaps.org/2015 ******************************************************************
Categories: Incoming News

Is it practical to write a strong chess engine in Haskell?

Haskell on Reddit - Tue, 09/02/2014 - 11:13am

I've been dabbling in writing a chess engine in Haskell for a while now. The main problem I am having is that a bitboard engine (the principle game representation is an array of fourteen 64 bit integers, one integer for every piece type, e.g. black bishop, white pawns) requires quick updating.

That is, I need to be able to non-patterned write and read an array really fast, at least at the assembly level. I used unsafe reads and writes to no avail. I'm not sure why it's so slow.

For those who are more experienced, is writing a mid strength or strong chess engine practical in Haskell? How about in idiomatic Haskell? I hear all the Haskell supporters saying that Haskell can do anything C can and almost just as fast, but I don't think I'll be convinced at least until a mid-strength chess engine is written.

What about in OCaml or a similar impure functional language?

Thanks for any answers.

Edit:

This got more response than I expected. The Haskell community is great.

I had to dig in the archives a little, but here is a quick repo I made: https://github.com/EricThoma/hchess.

Disclaimer: I wouldn't normally present this code online, as it probably has many errors and shows my novice. Most of it is very much C written in a do statement. The actual chess move-making isn't 100% accurate yet either. Frankly, I think I've grown enough as a programmer in the year or so since I wrote this that I'm a little embarrassed.

The way I am benchmarking it is by using a perft function, which is the most straightforward way to measure the raw move-making and move-generating speed of an engine. On my machine the engine barely cracks 1 million nodes per second. As a comparison, Stockfish is somewhere on the order of 50 million NPS, though I would think Stockfish runs on black magic if I couldn't see the source.

For those who understandably don't want to read my source, I am using Data.Vector.Unboxed.Mutable and Data.Vector.Unboxed and Data.IORef extensively, with unsafe writes and reads.

If I were to try again, I would definitely rewrite the engine base from the ground up. Also, I would write my own magic moves generator in Haskell (I have since done so in my C engine).

submitted by FrankAbagnaleSr
[link] [26 comments]
Categories: Incoming News

What Haskell feature do you miss the most when writing code in other languages?

Haskell on Reddit - Tue, 09/02/2014 - 8:52am

For me it's the type synonyms and newtype. In Java I end writing functions with signatures like "int(Collection<Pair<Integer, Integer>>, int)", which of course need all kinds of documentation so that I remember what they do in a week. If I could easily create new types, that signature could be "ReturnCode(Collection<Pair<EntryId, Count>>, RowId)" (I might not go that far, but you get the point).

Integer is final in Java, so if I wanted to make a new type, I would have to create a wrapper type with an int field and then access the int field every time I used the object. Drives me insane. And there's no way at all that I know of to create a synonym so that I can use either type interchangeably.

submitted by dont_memoize_me_bro
[link] [16 comments]
Categories: Incoming News

Third call for papers, IFL 2014

haskell-cafe - Tue, 09/02/2014 - 8:23am
Hello, Please, find below the third call for papers for IFL 2014. The submission page is now open. The submission date has been delayed to Sep. 8 2014 anywhere on the world. Please forward these to anyone you think may be interested. Apologies for any duplicates you may receive. best regards, Jurriaan Hage --- CALL FOR PAPERS 26th SYMPOSIUM ON IMPLEMENTATION AND APPLICATION OF FUNCTIONAL LANGUAGES - IFL 2014 NORTHEASTERN UNIVERSITY/BOSTON, USA OCTOBER 1-3, 2014 http://ifl2014.github.io We are pleased to announce that the 26th edition of the IFL series will be held at Northeastern University in Boston, USA. The symposium will be held from 1st to 3rd of October 2014. 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 2014 will be a venue for researchers to present and discuss new ideas and concepts, work in progress, and publication-ripe results related to the i
Categories: Offsite Discussion

Third call for papers, IFL 2014

General haskell list - Tue, 09/02/2014 - 8:23am
Hello, Please, find below the third call for papers for IFL 2014. The submission page is now open. The submission date has been delayed to Sep. 8 2014 anywhere on the world. Please forward these to anyone you think may be interested. Apologies for any duplicates you may receive. best regards, Jurriaan Hage --- CALL FOR PAPERS 26th SYMPOSIUM ON IMPLEMENTATION AND APPLICATION OF FUNCTIONAL LANGUAGES - IFL 2014 NORTHEASTERN UNIVERSITY/BOSTON, USA OCTOBER 1-3, 2014 http://ifl2014.github.io We are pleased to announce that the 26th edition of the IFL series will be held at Northeastern University in Boston, USA. The symposium will be held from 1st to 3rd of October 2014. 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 2014 will be a venue for researchers to present and discuss new ideas and concepts, work in progress, and publication-ripe results related to the i
Categories: Incoming News

CFP: PRDC2014 Call for Participation

General haskell list - Tue, 09/02/2014 - 5:23am
PRDC 2014 Call for Participation School of Computing, National University of Singapore, Singapore Nov. 19-21,2014 http://prdc.dependability.org/PRDC2014/index.html --------------------------------- Call for Participation http://prdc.dependability.org/PRDC2014/program.html --------------------------------- PRDC 2014 is the twentieth in this series of symposia started in 1989 that are devoted to dependable and fault-tolerant computing. PRDC is recognized as the main event in the Pacific area that covers the many dimensions of dependability and fault tolerance, encompassing fundamental theoretical approaches, practical experimental projects, and commercial components and systems. As applications of computing systems have permeated into all aspects of daily life, the dependability of computing systems has become increasingly critical. This symposium provides a forum for countries around the Pacific Rim and other areas of the world to exchange ideas for improving the dependability of computing systems. Topic
Categories: Incoming News

System.Process.readProcess "yes" [] "" >>= return .take 100

haskell-cafe - Tue, 09/02/2014 - 2:07am
I would expect the expression above to finish - but it doesn't. Is this a bug? _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe< at >haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Categories: Offsite Discussion

ICFP 2014 Talks

Haskell on Reddit - Tue, 09/02/2014 - 1:27am
Categories: Incoming News

New Functional Programming Job Opportunities

haskell-cafe - Mon, 09/01/2014 - 5:00pm
Here are some functional programming job opportunities that were posted recently: Senior Software Engineer (Functional) at McGraw-Hill Education http://functionaljobs.com/jobs/8737-senior-software-engineer-functional-at-mcgraw-hill-education Cheers, Sean Murphy FunctionalJobs.com
Categories: Offsite Discussion