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CFP: Erlang Workshop 2015

General haskell list - Tue, 03/24/2015 - 10:26pm
Hello all, Please find below the Call for Papers for the Fourteenth ACM SIGPLAN Erlang Workshop. Apologies for any duplicates you may receive. CALL FOR PAPERS =============== Fourteenth ACM SIGPLAN Erlang Workshop ----------------------------------------------------------- Vancouver, Canada, September 4, 2015 Satellite event of the 20th ACM SIGPLAN International Conference on Functional Programming (ICFP 2015) August 30 - September 5, 2015 _ Erlang is a concurrent, distributed functional programming language aimed at systems with requirements of massive concurrency, soft real time response, fault tolerance, and high availability. It has been available as open source for 16 years, creating a community that actively contributes to its already existing rich set of libraries and applications. Originally created for telecom applications, its usage has spread to other domains including e-commerce, banking, databases, and computer telephony and mes
Categories: Incoming News

The GHC Team: GHC Weekly News - 2015/03/24

Planet Haskell - Tue, 03/24/2015 - 8:20pm

Hi *,

It's time for the GHC weekly news. We've had an absence of the last one, mostly due to a lot of hustle to try and get 7.10 out the door (more on that shortly throughout this post). But now we're back and everything seems to be taken care of.

This week, in the wake of the GHC 7.10 release (which is occuring EOD, hopefully), GHC HQ met up for a brief chat and caught up:

  • This week GHC HQ met for only a very short time to discuss the pending release - it looks like all the blocking bugs have been fixed, and we've got everything triaged appropriately. You'll hopefully see the 7.10 announcement shortly after reading this.

We've also had small amounts of list activity (the past 6-8 weeks have been very, very quiet it seems):

  • Yitzchak Gale revived a thread he started a while back, which puttered out: bootstrapping GHC 7.8 with GHC 7.10. The long and short of it is, it should just about work - although we still haven't committed to this policy, it looks like Yitz and some others are quite adamant about it. ​

Some noteworthy commits that went into ghc.git in the past two weeks include:

Closed tickets this past week include: #9122, #10099, #10081, #9886, #9722, #9619, #9920, #9691, #8976, #9873, #9541, #9619, #9799, #9823, #10156, #1820, #6079, #9056, #9963, #10164, #10138, #10166, #10115, #9921, #9873, #9956, #9609, #7191, #10165, #10011, #8379, #10177, #9261, #10176, #10151, #9839, #8078, #8727, #9849, #10146, #9194, #10158, #7788, #9554, #8550, #10079, #10139, #10180, #10181, #10170, #10186, #10038, #10164, and #8976.

Categories: Offsite Blogs

Haskell-related PhD Studentship at Kent

haskell-cafe - Tue, 03/24/2015 - 5:12pm
Dear Haskellers, I am seeking a PhD student on a Haskell-related project: This would be a good opportunity for someone who is interested in applying Haskell ideas to real problems. The funding covers maintenance, EU student fees and research related expenses. But non-EU students are welcome to apply too. For Sep 2015 starting, the application deadline is 17 April 2015. If you are interested, please contact me at< at ><< at >>. Best wishes, Meng — Dr Meng Wang School of Computing University of Kent _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe< at >
Categories: Offsite Discussion - Tue, 03/24/2015 - 4:11pm
Categories: Offsite Blogs - Tue, 03/24/2015 - 4:11pm
Categories: Offsite Blogs

A beginner's troubles

Haskell on Reddit - Tue, 03/24/2015 - 4:07pm

Hi, so I'm a little embarrassed to say this, but I'm stuck on a problem that none of the books or video tutorials that I've seen has considered important enough to explain. So I should preface by saying that this is my first programming language. I thought I could hop in by reading some research along with the documentation and wrapping my head around some of the underlying math, but the biggest challenge has been implementation. Since most haskell programmers come from imperative backgrounds, I think they get the bulk of what they need to do on the command line and in the program files. I don't. I have an abstract understanding of the language, which I'm seeing has very little practical value with getting started.

So, here it goes:

I downloaded ghci, and I load it by going to my program files, and double clicking the ghci 7.8.3 application. It loads, and I'm on the command prompt. My problem is that though I can add numbers and things like that, I can't seem how to load 'scripts' or how to save them or where to save them to. My guess so far is that I save them into 'bin'. I'm not sure how I would have to preface these files. Do I put 'main' in a text file and save it as .hs into the bin folder?

To compound my confusion, I downloaded the Eclipse IDE (eclipseFP), and so far have everything other than hoogle, though I'm still trying to figure out how eclipse 'connects' with ghc. I did this because I could not figure out how to install cabal or hoogle just from the command line. I read that this was one of the things I needed to do in order to start. Can anyone clarify these super basic things for me?

The loading of files, the idea of a 'script', these are the things racking my brain. Please help!

submitted by onenode
[link] [13 comments]
Categories: Incoming News - Tue, 03/24/2015 - 3:01pm
Categories: Offsite Blogs

Type roles for UArray?

libraries list - Tue, 03/24/2015 - 2:57pm
So I was working on porting my libraries to work for GHC 7.10 and I ran into a snag. Unlike the concrete type Data.Array.Array, the concrete type Data.Array.Unboxed.UArray is defined as being nominal in the second type argument— is this a bug? If not, then why must it be nominal? Shouldn't (UArray a New) and (UArray a Old) have the same representation in memory? Using unsafeCoerce has always been safe here in the past...
Categories: Offsite Discussion - Tue, 03/24/2015 - 1:44pm
Categories: Offsite Blogs - Tue, 03/24/2015 - 1:29pm
Categories: Offsite Blogs - Tue, 03/24/2015 - 1:17pm
Categories: Offsite Blogs - Tue, 03/24/2015 - 1:06pm
Categories: Offsite Blogs - Tue, 03/24/2015 - 1:06pm
Categories: Offsite Blogs

parse error on input ‘|’

Haskell on Reddit - Tue, 03/24/2015 - 12:39pm

Here's the error and the code..

I understand that you shouldn't use tab because of how the compiler and text editor defines what a tab is, but I've not used tab, I've used ten spaces. What gives?

submitted by KatanaMaster
[link] [8 comments]
Categories: Incoming News

[Music] Note datatype help (i.e. how do I not put an A# in an F major scale?)

Haskell on Reddit - Tue, 03/24/2015 - 11:00am

So here's the commonest way to represent the western chromatic scale: data Note = A | As | B | C | Cs | D | Ds | E | F | Fs | G | Gs deriving (whatever you like)

This is the approach used here.

However, this means that I'm going to have things like this:

majorScale F -- returns F G A A' C D E

For anyone who knows at least the little music theory that I do, you know that this is a misspelling of F major.

I need show (or some other function I write) to return different things depending on the context, i.e. f Gs needs to say either G# or Ab.

How do I go about "structuring" the whole thing? I don't even want my data Note declaration to use either the sharp or flat representation - no "bias", as it were. Any ideas?

submitted by octatoan
[link] [20 comments]
Categories: Incoming News

Learning Haskell - Having trouble with Lambda Calculus Converter (Naked Expression)

Haskell on Reddit - Tue, 03/24/2015 - 10:57am

I've been struggling with this for a couple weeks. The lam2db function works fine. It can be called as follows: lam2db (Lam 0 (Lam 1 (Var 0)))

I'm trying to get the db2lam and isClosed functions working, but I've hit a brick wall. In its current state, it's complaining about a naked expression.

data Term = Var Int | Lam Int Term | App Term Term deriving (Eq, Show, Read) data BTerm = BVar Int | BLam BTerm | BApp BTerm BTerm deriving (Eq, Show, Read) lam2db :: Term -> BTerm lam2db x = f x [] where f :: Term -> [Int] -> BTerm f (Var x) vs = BVar (1 + vs !! (fromIntegral x)) f (App x y) vs = BApp (f x vs) (f y vs) f (Lam v y) vs = BLam a where a = f y (v : vs) --Example Test Data -- lam2db (Lam 0 (Lam 1 (Var 0))) db2lam :: BTerm -> Term db2lam x = f x 0 [] where -- or, instead of [], list of free vars f :: BTerm -> Int -> [Int] -> Term f (BVar i) _ vs = Var (at i vs) f (BApp a b) v vs = App x y where x = f a v vs y = f b v vs f (BLam a) v vs = Lam v y where y = f a (v+1) (v:vs) at (x:_) 0 x at i (_:xs) = at (i-1) xs isClosedB :: BTerm -> Bool isClosedB t = f t 0 where f (BVar n) d = n < d f (BLam a) d = f a (d + 1) f (BApp x y) d = f x d && f y d isClosedS :: Term -> Bool isClosedS = isClosedB . lam2db

Note: commenting out the line at (x:_) 0 x allows the program to compile and you can run the lam2db function.

submitted by Shoggoth269
[link] [comment]
Categories: Incoming News

Conduits versus enumerators - Tue, 03/24/2015 - 9:39am
Categories: Offsite Blogs

GSOC 2015 proposal feedback

haskell-cafe - Tue, 03/24/2015 - 9:04am
Hello, everyone! As someone on #haskell-gsoc IRC suggested, I would like to post my proposal. Please, if you have time, read it and send me your thoughts. Thanks! Here is the link: With regards, Nikita Kartashov _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe< at >
Categories: Offsite Discussion