I only just subscribed to this mailing list and I am a complete Haskell
newbie, so forgive me if this is too OT.
I noticed a recent thread about writing a Mathematica implementation in
Haskell. I think this is an excellent idea and would be a great project for a
Haskell newbie. I wrote a toy
I'm pretty new to Haskell, so forgive me if my question is due to my
non-functional way of thinking...
I have the following code:
module Main where
main = print solution
solution = solve 100
solve d = countUniqueFractions d 2 1 0
canBeSimplified (a,b) = gcd a b 1
countUniqueFractions
rwiggerink:
I'm pretty new to Haskell, so forgive me if my question is due to my
non-functional way of thinking...
I have the following code:
module Main where
main = print solution
solution = solve 100
solve d = countUniqueFractions d 2 1 0
canBeSimplified (a,b) = gcd a
jon:
On Wednesday 30 May 2007 06:58:36 Ketil Malde wrote:
On Tue, 2007-05-29 at 14:05 -0500, Doug Kirk wrote:
I *want* people (and companies) to move to Haskell
As a complete noob considering making a commercial venture into Haskell, may
I
ask what people's opinions are on this? Are
On Tue, 2007-05-29 at 21:28 +0100, Andrew Coppin wrote:
phantom types:
the types of ghost values (in other words, we are only interested in
the type, not in any value of that type).
Mmm... Still not seeing a great amount of use for this one.
The point is to 'tag' something with a type
On Tue, 2007-05-29 at 21:39 +0100, Andrew Coppin wrote:
My point is for most programs, trying to figure out exactly what you
want the program to do is going to be much harder than implementing a
program that does it.
And the solution is..to not say anything about what the program should
do?
On Tue, May 29, 2007 at 09:43:03PM +0100, Andrew Coppin wrote:
Henning Thielemann wrote:
On Sun, 27 May 2007, Andrew Coppin wrote:
But every now and then I discover an expression which is apparently not
expressible without them - which is odd, considering they're only
sugar...
Example?
i would just like to say thank you for all the extensive replies. after
fiddling with them for an afternoon i'm positive i grokked the concept.
it's just too bad the nice wrapper concept from [1] does not seem to be
directly applicable to fix in haskell, since they require untyped
On Tue, May 29, 2007 at 06:40:05PM -0700, Jason Dagit wrote:
Speaking of cute code, I'm fond of this:
map length . List.group . Control.Monad.Fix.fix $ show
fix show is cool in itself! :-)
Best regards
Tomek
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I am writing some webpage using haskell, I know Xhtml, but I also need some
other persons to write simple htmls
so I need a template system like cheetah in python, but I didn't find
anything through google. any help?
--
http://www.kamang.net
___
Ketil Malde wrote:
On Tue, 2007-05-29 at 21:39 +0100, Andrew Coppin wrote:
Also, for most programs the spec is far more complicated (and hence
prone to error) than the actual program, so...
Since the program *is* a (complete) specification of itself, a
specification need not be any longer
I've been planning to write a web templating system for a while now
but I haven't gotten around to it yet. I did write a small string
templating library that works like Python's string.Template but it's
probably not what you need. Here it is anyway:
On Mon, 2007-05-28 at 20:35 +0100, Neil Mitchell wrote:
Hi Duncan,
list the support files in the data-files: stanza in the .cabal file.
Then import the Paths_pkg module that Cabal generates for you. It
exports a few functions including:
getDataDir :: IO FilePath
A few questions:
Georg Sauthoff wrote:
while searching, if ghc can create packages as shared libraries I found
a ticket with a kind of non-accepted status:
http://hackage.haskell.org/trac/summer-of-code/ticket/46
But at the google SoC page it looks like an accepted project:
Hello,
In case anyone else finds this useful...
My linking problem was finally resolved by using the -fvia-C flag
when compiling with ghc.
Thanks to Stefan O'Rear who pointed out the possibility and wrote:
Does using -fvia-C help at all? The C compiler understands header
files and is
Andrew Coppin wrote:
My point is for most programs, trying to figure out exactly what you
want the program to do is going to be much harder than implementing a
program that does it.
Also, for most programs the spec is far more complicated (and hence
prone to error) than the actual program,
On Tue, 29 May 2007, Andrew Coppin wrote:
OTOH, how many function can you write with :: [Int] - Int? I can think
of a few...
You will probably more like to implement functions like
Ord a = [a] - a
Num a = [a] - a
and those generalized signatures tell you more. :-)
Duncan Coutts wrote:
On Mon, 2007-05-28 at 20:14 +0100, Andrew Coppin wrote:
You looked at the source to GHCi itself I presume? It uses the GHC API,
so it's a good place to start with building a variant of GHCi that uses
the GHC API :-)
No. Actually, as per the wiki, I was looking at the
On Sun, 27 May 2007, Evil Bro wrote:
I'm pretty new to Haskell, so forgive me if my question is due to my
non-functional way of thinking...
I have the following code:
Counting can be done elegantly by 'filter' and 'length':
length $ filter (1) $ Monad.liftM2 gcd [2..1000] [2..1000]
Stefan O'Rear wrote:
On Sat, May 26, 2007 at 07:41:19PM +0100, Andrew Coppin wrote:
Donald Bruce Stewart wrote:
The #haskell people have been working on this for about 3 years now.
The result is the 'runplugs' program, which I've talked about in
previous mails.
Counting can be done elegantly by 'filter' and 'length':
I figured out the following code after posting:
solve d = length [(y,x) | x - [2..d], y - [1..(x-1)], gcd x y == 1]
main = print (solve 100)
However when running it, it gave an answer of -1255316543. How on earth can
a length be
Neil Mitchell wrote:
Hi
I'm using the System.Timeout module from base, copied into my local
repo, so that I can work with GHC 6.6.1. My copy is at:
http://www.cs.york.ac.uk/fp/darcs/catch/catch_1/System/TimeoutGHC.hs
(but it is identical to the one in base)
Sadly, it doesn't seem to work for
Rodrigo Queiro wrote:
sorear pointed me to this paper a while ago:
http://citeseer.ist.psu.edu/peytonjones99stretching.html
I never tried any of the code in the end, but it will probably be useful?
An implementation of that memo table scheme can be found here:
On Wed, May 30, 2007 at 02:35:38PM +0200, Henning Thielemann wrote:
On Tue, 29 May 2007, Andrew Coppin wrote:
OTOH, how many function can you write with :: [Int] - Int? I can think
of a few...
You will probably more like to implement functions like
Ord a = [a] - a
Num a = [a] - a
On May 29, 2007, at 10:44 AM, apfelmus wrote:
Mark T.B. Carroll wrote:
I've been playing with Text.Parsers.Frisby to see how it stacks
against
other options and, while it's been great so far, I am finding that I
can't encode a grammar where what's acceptable depends on what's
already
Jon Harrop wrote:
On Wednesday 30 May 2007 06:58:36 Ketil Malde wrote:
On Tue, 2007-05-29 at 14:05 -0500, Doug Kirk wrote:
I *want* people (and companies) to move to Haskell
As a complete noob considering making a commercial venture into
Haskell, may I ask what people's opinions are on this?
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Robin Green wrote:
On Tue, 29 May 2007 19:28:02 -0400
Isaac Dupree [EMAIL PROTECTED] wrote:
Luckily, Haskell's laziness means that doing an extra postprocessing
pass doesn't necessarily yield two traversals requiring the whole
file to be stored
Evil Bro wrote:
Counting can be done elegantly by 'filter' and 'length':
I figured out the following code after posting:
solve d = length [(y,x) | x - [2..d], y - [1..(x-1)], gcd x y == 1]
main = print (solve 100)
However when running it, it gave an answer of -1255316543. How on
quantified types (forall/exist):
an easy way to memorize this is to think of 'forall' as a big 'and'
and of 'exists' as a big 'or'.
e :: forall a. a -- e has type 'Int' and type 'Bool' and type ..
e :: exists a. a -- e has type 'Int' or type 'Bool' or type ..
That doesn't entirely
On 5/26/07, Mark Engelberg [EMAIL PROTECTED] wrote:
I'd like to write a memoization utility. Ideally, it would look
something like this:
memoize :: (a-b) - (a-b)
memoize f gives you back a function that maintains a cache of
previously computed values, so that subsequent calls with the same
On 5/29/07, Andrew Coppin [EMAIL PROTECTED] wrote:
Claus Reinke wrote:
phantom types:
the types of ghost values (in other words, we are only interested in
the type, not in any value of that type).
Mmm... Still not seeing a great amount of use for this one.
Okay,
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Creighton Hogg wrote:
Now maybe I'm being dense here, but would you really *want* a way in
Haskell
to do something like
memo :: (a-b) - a-b
since it changes the semantics of the function?
It seems like a better abstraction would be to have
memo
On Wed, 30 May 2007 09:38:10 +0200, Tomasz Zielonka
[EMAIL PROTECTED] wrote:
On Tue, May 29, 2007 at 09:43:03PM +0100, Andrew Coppin wrote:
Henning Thielemann wrote:
On Sun, 27 May 2007, Andrew Coppin wrote:
But every now and then I discover an expression which is apparently
not
On 5/30/07, Isaac Dupree [EMAIL PROTECTED] wrote:
-BEGIN PGP SIGNED MESSAGE-
Hash: SHA1
Creighton Hogg wrote:
Now maybe I'm being dense here, but would you really *want* a way in
Haskell
to do something like
memo :: (a-b) - a-b
since it changes the semantics of the function?
It
Roberto Zunino wrote:
I actually misread the first one as
Control.Monad.Fix.fix ((1:) . tail . scanl (+) 1)
which is quite nice too, although
map (2^) [0..]
would be much simpler! ;-)
We apply a lesson learned from my last derivation. The lesson was to
look at s!!(n+1).
s = 1 : tail
Hello Federico,
Wednesday, May 30, 2007, 12:54:35 PM, you wrote:
Control.Monad.ST
And
Control.Monad.State
ST monad is just reduced IO monad which like IO organizes sequential
(imperative) ordr of execution but unlike IO supports only a small
closed set of operations - those working with
Neil Mitchell wrote:
Hi Duncan,
list the support files in the data-files: stanza in the .cabal file.
Then import the Paths_pkg module that Cabal generates for you. It
exports a few functions including:
getDataDir :: IO FilePath
A few questions:
1) How do I test this? I'll need to develop
On Wed, 2007-05-23 at 21:42 -0700, lebed wrote:
Hi, haskell-caffe!
I'm trying to build Gtk2Hs 0.9.11 under GHC 6.6.1 on Solaris 10 x86:
./mk/chsDepend -iglib:gtk:sourceview
sourceview/Graphics/UI/Gtk/SourceView/Types.chs
could not find {#import.chs on search path glib gtk sourceview
Jon Harrop wrote:
I noticed a recent thread about writing a Mathematica implementation in
Haskell.
Yeah, that was me.
I think this is an excellent idea and would be a great project for a
Haskell newbie.
Uh... I think it's actually a tad harder than it looks. [Understatement!]
I wrote a
Tomasz Zielonka wrote:
In the Ord variant, the result value pretty much has to come from the
input list or be bottom. It has to be bottom for the empty list. If
f :: Ord a = [a] - a and g preserves order (is monotonic) then
f (map g l) == g (f l)
This could be nice for testing Ord
Hallo,
On 5/30/07, Andrew Coppin [EMAIL PROTECTED] wrote:
OK, so you're saying that in 4 days you wrote something that
out-performs Mathematica, a program that has existed for decades and has
a vast, highly-funded RD effort behind it featuring some of the
brightest minds in the field?
I'm in
Why do you seem so in awe of Mathematica? It's just another language with
a good set of libraries. Claims that it is the best, fastest, etc comes
from Wolfram advertising, no doubt. :)
-- Lennart
On Wed, 30 May 2007, Andrew Coppin wrote:
Date: Wed, 30 May 2007 22:15:55 +0100
From:
On Wednesday 30 May 2007 22:15:55 Andrew Coppin wrote:
Jon Harrop wrote:
I wrote a toy Mathematica implementation in OCaml while I
waited to be viva'd for my PhD. It garnered so much interest that Wolfram
Research bought it from me for £4,500 and gave me several free copies of
I've found HOpenGL and the Debian package libghc6-opengl-dev. The former seems
to be very out of date (last release 2003) but I can't find any demos for the
latter.
Where should I go to get started with OpenGL and Haskell?
--
Dr Jon D Harrop, Flying Frog Consultancy Ltd.
OCaml for Scientists
On 5/30/07, Jon Harrop [EMAIL PROTECTED] wrote:
I've found HOpenGL and the Debian package libghc6-opengl-dev. The former
seems
to be very out of date (last release 2003) but I can't find any demos for
the
latter.
Where should I go to get started with OpenGL and Haskell?
For at least GHC
Jon Harrop wrote:
Where should I go to get started with OpenGL and Haskell?
Take a look at Gtk2Hs, which has OpenGL bindings.
For example, see http://darcs.haskell.org/gtk2hs/demo/opengl/
b
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On Wed, May 30, 2007 at 11:56:30PM +0100, Jon Harrop wrote:
On Wednesday 30 May 2007 22:15:55 Andrew Coppin wrote:
Jon Harrop wrote:
I wrote a toy Mathematica implementation in OCaml while I
waited to be viva'd for my PhD. It garnered so much interest that Wolfram
Research bought it
On Wed, 2007-05-30 at 16:09 -0700, Bryan O'Sullivan wrote:
Jon Harrop wrote:
Where should I go to get started with OpenGL and Haskell?
Take a look at Gtk2Hs, which has OpenGL bindings.
For example, see http://darcs.haskell.org/gtk2hs/demo/opengl/
The Gtk2Hs OpenGL stuff is only a
On 5/30/07, Jon Harrop [EMAIL PROTECTED] wrote:
Incidentally, when I try to recompile with optimizations turned on, GHC
refuses to work:
$ ghc htrace.hs -o htrace
$ ghc -O2 htrace.hs -o htrace
compilation IS NOT required
I must delete the target or edit the source to get it to recompile. I
See the examples/RedBook directory in the source code. It gives you a
good idea how the C-idioms are translated.
For an actual documentation on OpenGL you'll better take a look at
general OpenGL literature and translate them into Haskell. Note that
it's quite complex, though.
On 5/31/07, Jon
On 5/30/07, Jon Harrop [EMAIL PROTECTED] wrote:
I've found HOpenGL and the Debian package libghc6-opengl-dev. The former seems
to be very out of date (last release 2003) but I can't find any demos for the
latter.
Where should I go to get started with OpenGL and Haskell?
I started converting
The xmonad dev team is pleased to announce the 0.2 release of:
xmonad: a tiling window manager
http://xmonad.org
About:
Xmonad is a tiling window manager for X. Windows are arranged
automatically to tile the screen without gaps or overlap,
On Wednesday 30 May 2007 07:04:31 Jon Harrop wrote:
3. The language: the hardest part of reimplementing Mathematica is
inferring what it means (there are no formal evaluation semantics). Once
you've done that it is just a case of implementing an extensible term
rewriter and putting in about 20
This is a crazy idea I've been working on: overload the syntax x y so it can
mean function application f x = f(x) or multiplication x y = x*y. The
reason is simply that I appreciate the brevity of MLs function application
but I also appreciate the brevity of Mathematica's multiplication.
Is
Hello =),
I'm puzzled, and maybe someone can help me out. Why does this happens?
$ time ghci -e last $ take 100 $ [1..100]
100
real0m0.673s
user0m0.554s
sys 0m0.024s
$ time ghci -e last $ take 100 $ [1..]
*** Exception: stack overflow
real0m1.305s
user
On Wed, May 30, 2007 at 11:41:55PM -0300, Felipe Almeida Lessa wrote:
Hello =),
I'm puzzled, and maybe someone can help me out. Why does this happens?
$ time ghci -e last $ take 100 $ [1..100]
100
real0m0.673s
user0m0.554s
sys 0m0.024s
$ time ghci -e last $
On 5/30/07, Stefan O'Rear [EMAIL PROTECTED] wrote:
No, because anything you file will be closed immediately as duplicate
of http://hackage.haskell.org/trac/ghc/ticket/1097;
Oh, sorry for not having searched better for this problem on the net.
I spend a lot of time finding out where the stack
On Thu, May 31, 2007 at 12:15:01AM -0300, Felipe Almeida Lessa wrote:
On 5/30/07, Stefan O'Rear [EMAIL PROTECTED] wrote:
No, because anything you file will be closed immediately as duplicate
of http://hackage.haskell.org/trac/ghc/ticket/1097;
Oh, sorry for not having searched better for this
On 5/31/07, Stefan O'Rear [EMAIL PROTECTED] wrote:
You don't need to feel too bad about this:
[snip]
Don't worry, I should have googled anyway =).
BTW, how do you usually proceed when finding out why your code said
Segmentation fault.? (should this question move to a new thread?)
Thanks,
On Thu, May 31, 2007 at 12:34:36AM -0300, Felipe Almeida Lessa wrote:
On 5/31/07, Stefan O'Rear [EMAIL PROTECTED] wrote:
You don't need to feel too bad about this:
[snip]
Don't worry, I should have googled anyway =).
BTW, how do you usually proceed when finding out why your code said
Hello,
I just moved to ghc-6.6.1and was wondering if there is an automatic
way to update the various packages I had installed previously.
thanks,
jeff
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Hi
What is the basic philosophy for Bool being a member of Ord?
What justifies False True?
many Thanks in advance,
Paul
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What is the basic philosophy for Bool being a member of Ord?
What justifies False True?
The implication ordering,
which on this smallest non-trivial Boolean algebra
happens to be a linear order,
is therefore the natural candidate for Ord,
the type class of ``default linear orders''.
Am Donnerstag, 31. Mai 2007 05:52 schrieb PR Stanley:
What is the basic philosophy for Bool being a member of Ord?
you can do sth like
Data.Set.fromList [minBound .. maxBound] :: Data.Set.Set Bool
What justifies False True?
in most interpretations this equals:
False == 0
True == 1
and == (*)
Hi, buddies. I am a newbie on Haskell. Recently I want to implement a simple
Lattice in Haskell, but I met some difficulties.
Scrap of the code is as below, but I met syntax error:
class Lattice e where
join :: e - e - e
meet :: e - e - e
-- associative law
join x (join y
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