Tamas K Papp wrote:

On Sun, Sep 03, 2006 at 12:47:45PM +0400, Bulat Ziganshin wrote:

...

i also suggest you to start write some library. there is enough useful libs that are still bnot implemented because lack of time (and insterest in such simple code) on side of more experienced programmers. i once proposed you to write strings library, another interesting and useful thing will be gzip/bzip2-lib bindings

Bulat,

I would be happy to write a strings library, I just don't know that it is supposed to do... (I have no CS education, only math/economics). If you show me the specifications or documentation in another language, I would write one as practice.

What about a library for interval arithmetic [1]? I'd imagine it could start something like: data Interval a = Interval !a !a deriving (Eq, Show) instance Num a => Num (Interval a) where Interval llow lhigh + Interval rlow rhigh = Interval (min llow rlow) (max lhigh rhigh) The Interval type would probably need to explicitly represent several kinds of intervals eg (-infinity, x] etc and there are some tricky issues about what to do with the operations whose result sometimes needs to be represented by more than one interval to be useful such as division by an interval containing zero eg you might want to use a list of intervals to deal with these cases: instance Num a => [Interval a] where ... ie [Interval 5 5] / [Interval -1 1] = [FromNegInfinityTo -5, ToPosInfinityFrom 5] though using a list may make things too slow (ideally it would be nice to have interval arithmetic that's as fast as normal floating point arithmetic - is this possible?) Alternatively, these cases could just be undefined though that might limit the usefulness of the lib. Another extremely useful thing would be a symbolic math library with a BSD (or LGPL) license... And yet another extremely useful thing would be a good library for numerical computations (there is GSLHaskell but that's licensed under GPL so there still seems to be a gap for something similar using LGPL or BSD). In general if you look at http://www.haskell.org/haskellwiki/Libraries_and_tools/Mathematics there appear to be many extremely useful libs already written, but unfortunately a lot of them are not BSD compatible so I think there is a huge gap for math related libs that people can use for commercial projects. Anyway just an idea :-), Brian. [1] http://en.wikipedia.org/wiki/Interval_arithmetic -- Logic empowers us and Love gives us purpose. Yet still phantoms restless for eras long past, congealed in the present in unthought forms, strive mightily unseen to destroy us. http://www.metamilk.com

On Sep 3, 2006, at 8:22 AM, Brian Hulley wrote:

Tamas K Papp wrote:

...

On Sun, Sep 03, 2006 at 12:47:45PM +0400, Bulat Ziganshin wrote:

...

i also suggest you to start write some library. there is enough useful libs that are still bnot implemented because lack of time (and insterest in such simple code) on side of more experienced programmers. i once proposed you to write strings library, another interesting and useful thing will be gzip/bzip2-lib bindings

Bulat,

I would be happy to write a strings library, I just don't know that it is supposed to do... (I have no CS education, only math/economics). If you show me the specifications or documentation in another language, I would write one as practice.

What about a library for interval arithmetic [1]?

I'll sign up to write this just as soon as I can control the floating- point rounding mode in purely functional code with low overhead. :-) Without this control, you end up with a toy which can't actually be used for real work. Sadly, I don't think GHC's built-in thread scheduler plays nicely with floating-point mode changes unless you do them across the entire program for the entire run. The interval multiplication algorithm turns out to be exciting. :-) -Jan-Willem Maessen

On Mon, Sep 04, 2006 at 07:39:40PM +0200, apfelmus@quantentunnel.de wrote:

The ultimate Haskell challenge is of course the ICFP contest http://icfpcontest.org/ There is also the International ACM Programming Contest http://acm.uva.es/problemset/

I don't know about the services mentioned above, but Sphere Online Judge (http://www.spoj.pl/) allows you to submit solutions written in Haskell (and many other programming languages). Best regards Tomasz

On Mon, Sep 04, 2006 at 10:53:49PM +0100, Neil Mitchell wrote:

...

From that we can see Haskell is the 7th best programming langauge - and that number of problems solved is almost exactly the same as rank. I think perhaps we need a little project to conquer this benchmark like we did the gentoo/debian ones....

I'll have a go and scraping together some people for this, and starting up a wiki page tomorrow. Lots of little programs, no particular need for optimisation yet, so could be a great chance for beginners and the more experienced who'd just like a quick hack once in a while.

This, and especially publishing solutions on the Wiki, could be against the spirit of SPOJ. Here is a relevant piece from the FAQ: Q: the submitted programs, will they be made public here at some time ? or at least those, where the author agrees ? A: The problemset is persistent and some ranks are affected by number of solved problems. If the solutions are published it would be to easy to just copy the solution and submit it. Hence they will not be published. Authors are also requested not to publish their exact code. It is better and maybe more beneficial for everybody to discuss ideas and algorithms of solutions. The code is visible to admins and the problem setter of the task he stated. For some of the problems taken from competitions around the world it is probable that you may find a coded solutionon some other site. It is encouraged though that you understand the algorithm and code it yourself. This is rather a competition between people, not between languages. The rule of not publishing solutions can decrease the educational value of such service. But as they say, the problemset is persistent, the contests never ends. Many of those problems were taken from some olympiads and contests - those finish at some point, and then the solutions can be published. Best regards Tomasz

On 9/5/06, Tomasz Zielonka wrote:

On Mon, Sep 04, 2006 at 07:39:40PM +0200, apfelmus@quantentunnel.de wrote:

...

The ultimate Haskell challenge is of course the ICFP contest http://icfpcontest.org/ There is also the International ACM Programming Contest http://acm.uva.es/problemset/

I don't know about the services mentioned above, but Sphere Online Judge (http://www.spoj.pl/) allows you to submit solutions written in Haskell (and many other programming languages).

As a Haskell newbie I've found the SPOJ challenges challenging, usually due to the time contraints placed on solutions. Another 'challenge site' I've enjoyed tremendously is Project Euler at http://mathschallenge.net/index.php?section=project Toby.