G'day all.
Quoting aditya siram aditya.si...@gmail.com:
I'm a little confused about this too. I've seen many functions defined like:
f x = (\s - ...)
which is a partial function because it returns a function and is the same as:
f x s = ...
Off the top of my head the State monad makes
Dear Friends,
I'm looking for some help from the Haskell community. I hope this is the right
place to ask for information.
I'm putting together a website aimed at high school students and teachers, and
would like to add a few paragraphs to the following page:
On 03/05/2010, at 06:02, Jaco van Iterson wrote:
I was just wondering what methods are best to design/model the software in
bigger projects when you are planning to use Haskell.
Is there no difference compared to other languages? Are there any Haskell
tools?
In addition to what Don said,
Also, one more thing - if someone could write some comments to go along with
the source code that explain what it is doing, that would be really helpful. I
can see the general structure, but I don't know the ins and outs of Haskell. If
someone could augment the example with comments explaining
If you are running from GHCi, just type run 100 at the prompt..
If you intend to compile it, you have to add
main = print $ run 100
The compiler adds a call to main::IO (), which is intended to be the main
entry point of your code.
We need to add print, as run has type
run::Int-[Door]
so run
Ivan Miljenovic ivan.miljeno...@gmail.com disse:
On 3 May 2010 14:17, aditya siram aditya.si...@gmail.com wrote:
I'm a little confused about this too. I've seen many functions defined like:
f x = (\s - ...)
which is a partial function because it returns a function and is the same as:
f x s =
Peter Verswyvelen wrote:
Actually, I believe that many Yampa examples do separate the drawing
from the update... The arrow provides the game data that *can* be
rendered. If you provide interpolators for that game data, you can
still achieve the same as is explained in fix your timesteps (in my
Don Stewart d...@galois.com writes:
Some key points:
* Avoid partial functions
As an important corollary to this one I would add: never throw
exceptions from pure code. They often leak out from catch blocks and
ruin your day.
G
--
Gregory Collins g...@gregorycollins.net
On Sat, May 1, 2010 at 7:11 PM, Sean Leather leat...@cs.uu.nl wrote:
I want to generalize a set of functions from lists to some functor type. I
require the following three operation types.
f a
a - f a
f a - f a - f a
Since f is a functor, FunctorPlus and Pointed together get you
On Sun, May 2, 2010 at 4:23 AM, Sebastian Fischer
s...@informatik.uni-kiel.de wrote:
Ideally, every MonadPlus instance would also be an Alternative instance and
every Alternative instance would be an instance of Monoid. You may find it
unfortunate that there are so many operations for the
On Sun, May 2, 2010 at 6:23 PM, Ben midfi...@gmail.com wrote:
hello --
i'm putting the finishing touches on a cabal package based on what
felipe gave, i've managed to make it an arrow transformer which is
nice. i have a few issues though.
1) i know it is not possible to add class
XMPP[1] is a protocol for asynchronous communication via long-lived
XML documents. It is most famous for underlying the Jabber and Wave
protocols, but is also used for a variety of cases where security and
extensibility are useful.
My library, network-protocol-xmpp[2], is an implementation of
Reasons to learn Haskell include:
Lazy evaluation can make some kinds of algorithms possible to implement that
aren't possible to implement in other languages (without modification to the
algorithm).
Strict type system allows for a maximum number of programming errors to be
caught at compile time.
On Mon, 3 May 2010, Gregory Collins wrote:
Don Stewart d...@galois.com writes:
Some key points:
* Avoid partial functions
As an important corollary to this one I would add: never throw
exceptions from pure code. They often leak out from catch blocks and
ruin your day.
It's not
Henning Thielemann lemm...@henning-thielemann.de writes:
It's not possible to throw exceptions from pure code. You can only
call 'error' and that's another name for 'undefined', i.e. you have a
partial (non-total ?) function.
On Mon, May 3, 2010 at 9:17 AM, Kyle Murphy orc...@gmail.com wrote:
Reasons to learn Haskell include:
Lazy evaluation can make some kinds of algorithms possible to implement that
aren't possible to implement in other languages (without modification to the
algorithm).
One could say the reverse
Dear Kyle,
Improving the example to use more idiomatic Haskell is a good idea. I'm happy
for you to propose another approach entirely. I'm simply not skilled in Haskell
to do anything better.
However, thanks for writing some comments for the code below, it will certainly
help.
Kind regards,
On Mon, May 3, 2010 at 11:34 AM, Casey Hawthorne cas...@istar.ca wrote:
Strict type system allows for a maximum number of programming errors to be
caught at compile time.
I keep hearing this statement but others would argue that programming
errors caught at compile time only form a minor
Are you really sure about that... it might cause a typing error if you misspell
something.
Proposal: The double typing error
Kind regards,
Samuel
On 4/05/2010, at 3:34 AM, Casey Hawthorne wrote:
I don't mean tpynig errros.
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On Mon, May 3, 2010 at 9:34 AM, Casey Hawthorne cas...@istar.ca wrote:
Strict type system allows for a maximum number of programming errors to be
caught at compile time.
I keep hearing this statement but others would argue that programming
errors caught at compile time only form a minor subset
Hi Samuel
I'm not sure Haskell is an ideal language for school age teaching,
DrScheme seems a more obvious choice.
Paul Hudak made a good case for Haskell as a learning language with
his School of Expression book, but if you weren't directly following
that book, I think it would be hard to make
Henning Thielemann lemm...@henning-thielemann.de writes:
http://www.haskell.org/ghc/docs/6.12.2/html/libraries/base-4.2.0.1/Control-Exception.html#v%3Athrow
I see. This should be forbidden, at all! :-)
Why is this worse than or different from 'error'? To me it looks like
'error', only with a
Dear Stephen,
The goal of the site is not an introduction to programming for the beginner.
Its a site designed to expose students and teachers to the multitudes of
programming languages out there.
DrScheme looks like a good approach.
Kind regards,
Samuel
On 4/05/2010, at 4:03 AM, Stephen
Ketil Malde schrieb:
Henning Thielemann lemm...@henning-thielemann.de writes:
http://www.haskell.org/ghc/docs/6.12.2/html/libraries/base-4.2.0.1/Control-Exception.html#v%3Athrow
I see. This should be forbidden, at all! :-)
Why is this worse than or different from 'error'? To me it looks
Hello Café,
I don't know if you know
conkyhttp://en.wikipedia.org/wiki/Conky_%28software%29.
It's a well-known open-source system monitor (a software that displays
information on the desktop, like CPU frequency, disk usage, network rate,
etc.).
It is quite good, but it's very descriptive, and
The problem with dynamic typing is that it has a much higher chance of
having a subtle error creep into your code that can go undetected for a long
period of time. A strong type system forces the code to fail early where
it's easier to track down and fix the problem, rather than trying to perform
Dear Kyle,
I've recevied the following program. You did a fantastic job of explaining the
other one, but as you said it wasn't a great approach, if you have a moment
could you explain this one?
doorOpen :: Int - Bool
doorOpen door = doh door door
doh :: Int - Int - Bool
doh door 0 = True
doh
Ketil Malde ke...@malde.org writes:
Henning Thielemann lemm...@henning-thielemann.de writes:
http://www.haskell.org/ghc/docs/6.12.2/html/libraries/base-4.2.0.1/Control-Exception.html#v%3Athrow
I see. This should be forbidden, at all! :-)
Why is this worse than or different from 'error'?
(Note: Reply-to is set to haskell-cafe@haskell.org)
Hello,
I am very pleased to announce Happstack 0.5.0. It should install
cleanly from hackage via:
cabal install happstack
If it does not, please report errors to the happstack mailing list:
http://groups.google.com/group/HAppS
(You
Hi all
I have been using an old version of eclipsepf for quite some time now on my
windows machine. Recently I saw that there is a newer version, as well as a
newer version of haskell. However, I am not able to get it all to work. I
wonder if you are able to help me out.
First, I installed the
One of my students has worked on scripting approach in Haskell:
http://web.engr.oregonstate.edu/~erwig/papers/abstracts.html#SLE09
--
Martin
On May 3, 2010, at 9:51 AM, Limestraël wrote:
Hello Café,
I don't know if you know conky. It's a well-known open-source system monitor
On May 3, 2010, at 10:57 AM, Jeremy Shaw wrote:
- hide IxSet constructor. use ixSet instead.
- improved efficiency of gteTLE, getGTE, and getRange
- get rid of Dynamic, just use Data.Typeable (internal change)
- added deleteIx
- Eq and Ord instances for IxSet
- removed
Does anyone have installer for gtk2hs for Haskell Platform 2010.1.0.0?
Regards
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On Montag 03 Mai 2010 19:58:54, Han Joosten wrote:
Hi all
Then, again i tried 'runhaskell setup.hs configure', but this failed
again with exactly the same message as before. It seems that all
packages that I installed dissapeared!
I think it's the fact that cabal-install by default does
In my opinion code is 'right' when it conforms to the specification.
Haskell's type system allows the programmer to express a part of the
specification in the types, which then get checked by the
compiler/type-checker. This is where I see the biggest benefit of a
very expressive statically checked
HELLO,
I AM JIM JONES AND I WILL LIKE TO KNOW IF YOU CARRY (MITYVAC VACUUM BRAKE) FOR
SALE.AND IF YES,REPLY ME BACK WITH YOUR WEBSITE SO THAT I CAN SELECT THE ONE
THAT I WILL LIKE TO ORDER,ALSO I AM SHIPPING THE (MITYVAC VACUUM BRAKE) TO ONE
OF MY COMPANY IN SWEDEN AND I WILL RECOMMEND A
On Mon, 2010-05-03 at 19:21 +0100, Maciej Piechotka wrote:
Does anyone have installer for gtk2hs for Haskell Platform 2010.1.0.0?
Regards
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Hi Maciej,
Maciej Piechotka uzytkown...@gmail.com writes:
On Mon, 2010-05-03 at 19:21 +0100, Maciej Piechotka wrote:
Does anyone have installer for gtk2hs for Haskell Platform 2010.1.0.0?
Regards
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16.04.2010 3:07, Stephen Tetley ?:
Hello
You can build GNU's regex C-library with MinGW from source and this
will give you regex.h and libregex.a / libregex.dll.
I think I've only had the Haskell regex-posix package half-working
doing this though; i.e. I could build and install regex-posix
On Montag 03 Mai 2010 21:40:13, Stanislav Chernichkin wrote:
I think it would be nice if someone will write an article on
Haskell Wiki on building regex-posix, but my English is not
good enough for such things.
You could start the article nevertheless and let others polish the English
then.
I
Hi
Pressing documentation-link here http://happstack.com/index.html I still
get the 0.4.1 version.
But impressive set of new features.
/Mads
On Mon, 2010-05-03 at 12:57 -0500, Jeremy Shaw wrote:
(Note: Reply-to is set to haskell-cafe@haskell.org)
Hello,
I am very pleased to announce
The original rangemin project was my first Haskell package, and definitely
my first attempt at super-advanced algorithms work in Haskell. (I here
define super-advanced as not in MIT OpenCourseWare undergraduate
algorithms lecture notes from any year.)
Here's the problem: Suppose we have an array
Hi,
You can take the xmonad approach: the configuration file is written in
Haskell and compiled, so no need for another language.
Cheers,
Thu
2010/5/3 Martin Erwig er...@eecs.oregonstate.edu:
One of my students has worked on scripting approach in Haskell:
Thanx Daniel! This did the trick.
Han.
--
View this message in context:
http://old.nabble.com/eclipse%2C-haskell-platform-and-windows.-Installation-problem.-tp28438196p28440001.html
Sent from the Haskell - Haskell-Cafe mailing list archive at Nabble.com.
Gregory Collins g...@gregorycollins.net writes:
Henning Thielemann lemm...@henning-thielemann.de writes:
http://www.haskell.org/ghc/docs/6.12.2/html/libraries/base-4.2.0.1/Control-Exception.html#v%3Athrow
I see. This should be forbidden, at all! :-)
Why is this worse than or different from
Hey everyone,
After I upgraded to a newer cabal-install my cabal-install broke again: I get a
Bus Error when doing cabal update or cabal install something. The version
that was bundled with the Haskell platform worked fine, but now it's broken
again. I'm not sure what it was that went wrong or
On Mon, May 3, 2010 at 2:21 PM, Chris Eidhof ch...@eidhof.nl wrote:
Hey everyone,
After I upgraded to a newer cabal-install my cabal-install broke again: I
get a Bus Error when doing cabal update or cabal install something. The
version that was bundled with the Haskell platform worked fine,
That's also the approach Yi uses. I'm fairly certain there's a library on
hackage that makes writing up programs in that style fairly trivial,
although I can't remember the details right now. I'd look up Yi as a
starting point.
-R. Kyle Murphy
--
Curiosity was framed, Ignorance killed the cat.
On Mon, May 3, 2010 at 5:47 PM, Kyle Murphy orc...@gmail.com wrote:
That's also the approach Yi uses. I'm fairly certain there's a library on
hackage that makes writing up programs in that style fairly trivial,
http://hackage.haskell.org/package/dyre
--
gwern
Thank you all, that's very interesting.
Martin, I've started reading the paper, I like the way you think about what
a scripting language should provide (traceability, error handling and a
type system).
But, hold me if I'm wrong, but at no moment in the paper you made you own
language? It's a
On May 3, 2010, at 3:19 PM, Mads Lindstrøm wrote:
Hi
Pressing documentation-link here http://happstack.com/index.html I
still
get the 0.4.1 version.
Yeah, that is updated now. Made the announcement, before I had really
finished everything. Sorry about that.
-
xmonad is my favorite WM. BTW, why canot i receive any email from its
mailinglist (i have subscribed from
http://www.haskell.org/mailman/listinfo/xmonad)?
minh thu wrote:
Hi,
You can take the xmonad approach: the configuration file is written in
Haskell and compiled, so no need for
Hi,
You do not need a DSL at all, in fact. The simplest way to do this, if you use
GHC, is to use the GHC api. This can compile everything for you, and return a
value with type Dynamic, from Data.Dynamic and Data.Typeable. It is
type-safe, you can write within very little time (even if the
Hello -cafe,
When I started learning Haskell, I saw the AI page [1] which aimed at
creating a sound, uniform and handy framework for AI programming in Haskell.
I added my name on it and thought a bit about it. I even wrote a first
version of HNN [2], a neural network library, quite early in my
On 4 May 2010 11:59, Alp Mestanogullari a...@mestan.fr wrote:
I found that idea to be great but did not see any actual effort around this.
So, I'm now thinking again about that and even enlarging it to mathematics
AI. Thus, I would like to have an idea of the number of people interested in
On 4 May 2010 04:21, Maciej Piechotka uzytkown...@gmail.com wrote:
Does anyone have installer for gtk2hs for Haskell Platform 2010.1.0.0?
Considering that there is as yet no release of gtk2hs that supports
GHC-6.12.*, it seems unlikely. At best someone may have taken a
snapshot of the darcs
Hi Ivan,
Ivan Miljenovic ivan.miljeno...@gmail.com writes:
On 4 May 2010 04:21, Maciej Piechotka uzytkown...@gmail.com wrote:
Does anyone have installer for gtk2hs for Haskell Platform 2010.1.0.0?
Considering that there is as yet no release of gtk2hs that supports
GHC-6.12.*, it seems
Ok guys, Ivan takes care of graphs =)
Note that it's more about computational mathematics, for things one would do
for example with Mathematica or similar softwares.
Maybe interested people could come and discuss that on IRC, as a beginning,
on a #haskell-math channel for example ?
On Tue, May
On Mon, May 3, 2010 at 11:07 AM, Kyle Murphy orc...@gmail.com wrote:
The problem with dynamic typing is that it has a much higher chance of
having a subtle error creep into your code that can go undetected for a long
period of time. A strong type system forces the code to fail early where
it's
On May 3, 2010, at 3:45 PM, Limestraël wrote:
Thank you all, that's very interesting.
Martin, I've started reading the paper, I like the way you think about what a
scripting language should provide (traceability, error handling and a type
system).
But, hold me if I'm wrong, but at no
lrpalmer:
What I seem to be getting at is this plane of type systems:
Constrained - Expressive
Unreliable
| (C)
|(test suites)
| (C++).
|
On 4 May 2010 13:30, Luke Palmer lrpal...@gmail.com wrote:
Here is a contrived example of what I am referring to:
prefac f 0 = 1
prefac f n = n * f (n-1)
fac = (\x - x x) (\x - prefac (x x))
I can't work out how this works (or should work rather); is it meant
to be using church numerals or
prefac is just a normal factorial function with recursion factored out. fix
prefac 5 gives 120, for example.
On Tue, May 4, 2010 at 12:13 AM, Ivan Miljenovic
ivan.miljeno...@gmail.comwrote:
On 4 May 2010 13:30, Luke Palmer lrpal...@gmail.com wrote:
Here is a contrived example of what I am
On Tue, May 4, 2010 at 12:13 AM, Ivan Miljenovic
ivan.miljeno...@gmail.com wrote:
On 4 May 2010 13:30, Luke Palmer lrpal...@gmail.com wrote:
Here is a contrived example of what I am referring to:
prefac f 0 = 1
prefac f n = n * f (n-1)
fac = (\x - x x) (\x - prefac (x x))
I can't work out
On Mon, May 3, 2010 at 10:13 PM, Ivan Miljenovic
ivan.miljeno...@gmail.com wrote:
On 4 May 2010 13:30, Luke Palmer lrpal...@gmail.com wrote:
Here is a contrived example of what I am referring to:
prefac f 0 = 1
prefac f n = n * f (n-1)
fac = (\x - x x) (\x - prefac (x x))
I can't work out
On Tue, 2010-05-04 at 00:45 +0200, Limestraël wrote:
Minh, Kyle, Gwern, the dyre approach seems to be very interesting too.
But if I understood well, we also have to recompile at run-time the
configuration haskell script?
So the final application (Yi, for instance) will need GHC to be
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