Bryan Burgers wrote:
I did not look at it long enough to tell you why there is an infinite
loop. However, think about it on a high level with me.
You want a stream of these random numbers (I'm not sure what a
triangular distribution is, but that's okay). To get one of these, you
take two
Tillmann Rendel wrote:
(A) will be executed before (B) because of the IO monad. But you want r
to be returned before rest is computed. I would split tpdfs in two
functions: a pure function converting a infinite list of random numbers
to another infinite list of random numbers, and an
An interesting study on problem resolution and feedback on some
technical mailing lists,
How to Help Mailing Lists Help Readers
(Results of Recent Data Analysis)
http://praxagora.com/andyo/professional/mailing_list_follow_up/
including graphs! :)
With conclusions at the end on how
Miguel Mitrofanov miguelimo38 at yandex.ru writes:
Just being curious.
There are a lot of tutorials ensuring the reader that, although
Haskell is based on category theory, you don't have to know CT to use
Haskell. So, is there ANY Haskell tutorial for those who do know CT?
I don't need
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of ???
help
haskell for web code
http://www.haskell.org/haskellwiki/Applications_and_libraries/Web_programming
Try a few of these out (whatever meets your needs). For web apps WASH and HAppS
seem popular. Feel free to ask the
Hi
Reading through the code to lex, it appear that it will return
[(,)] if and only if all isSpace t.
If this is really the case, does it make sense to state all isSpace t?
It has a much clearer meaning to me.
I think 'lex' is supposed to not understand (haskell-style) comments -
which I
hMapping polymorphic functions is indeed quite challenging, but can
be done. That was the topic of the message
Type-class overloaded functions: second-order typeclass programming
with backtracking
http://okmij.org/ftp/Haskell/poly2.txt
The challenge is how to avoid
And this is where I think Haskell has it all over C++, Java, and the
rest. Haskell is easy to learn at a simple level, and hard to learn at
the expert level, but once learned is very powerful and has excellent
payoffs in terms of productivity. With C++ or Java, the expertise is
somewhat easier to
On 7/17/07, Bayley, Alistair [EMAIL PROTECTED] wrote:
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of ???
help
haskell for web code
http://www.haskell.org/haskellwiki/Applications_and_libraries/Web_programming
Try a few of these out (whatever meets your needs). For web
Haskell On Rails
-邮件原件-
发件人: Martin Coxall [mailto:[EMAIL PROTECTED]
发送时间: 2007年7月17日 16:44
收件人: Bayley, Alistair
抄送: 王清军; [EMAIL PROTECTED]; haskell Café
主题: Re: [Haskell-cafe] RE: haskell for web
On 7/17/07, Bayley, Alistair [EMAIL PROTECTED] wrote:
From: [EMAIL PROTECTED]
why 'Haskell On Rails' ?
-邮件原件-
发件人: Martin Coxall [mailto:[EMAIL PROTECTED]
发送时间: 2007年7月17日 16:44
收件人: Bayley, Alistair
抄送: 王清军; [EMAIL PROTECTED]; haskell Café
主题: Re: [Haskell-cafe] RE: haskell for web
On 7/17/07, Bayley, Alistair [EMAIL PROTECTED] wrote:
From: [EMAIL PROTECTED]
hi folks --
a haskell newbie here, searching for comments and wisdom on my code.
i had a project to try to implement external sort in haskell as a
learning exercise. (external sort is sorting a list that is too large
to fit in main memory, by sorting in chunks, spooling to disk, and
then
| It seems the -O2 option can give a significant speed increase relative
| to just the -O option. This is contrary to the documentation which says
-O2 switches on SpecConstr, which has improved quite a bit in the last year or
so. There's a paper on my home page about it (Constructor
On 7/17/07, Martin Coxall [EMAIL PROTECTED] wrote:
Me too, which is why I find your statement that expertise in C++ is
easy to acquire. Seeing some of my colleagues' code is enough to tell
me that this is most definitely not the case.
You're quite right. That was careless on my part. Though
The following is a slap-dash program for generating a list of pairs of
words which differ by, at most, one letter. It's quite verbose at the
moment, because (a) that was the way I wrote it, a snippet at a time,
and (b) I lack the wit to make it shorter.
Can anyone recommend ways to make this
On Tue, Jul 17, 2007 at 19:43:51 +1000, Thomas Conway wrote:
On 7/17/07, Martin Coxall [EMAIL PROTECTED] wrote:
Me too, which is why I find your statement that expertise in C++ is
easy to acquire. Seeing some of my colleagues' code is enough to tell
me that this is most definitely not the case.
On 7/17/07, Magnus Therning [EMAIL PROTECTED] wrote:
On Tue, Jul 17, 2007 at 19:43:51 +1000, Thomas Conway wrote:
On 7/17/07, Martin Coxall [EMAIL PROTECTED] wrote:
Me too, which is why I find your statement that expertise in C++ is
easy to acquire. Seeing some of my colleagues' code is enough
Hugh Perkins wrote:
Your solution looks really elegant, and runs insanely fast. Can you
explain how it works?
I will jump in and explain, using a more finely named version:
xkcd_c287' = foldr
(\cost without -
let (poor, rich) = splitAt cost without
with
On 16 Jul 2007, at 19:53, Stefan Holdermans wrote:
I wrote:
I came up with [...]
apfelmus' solution is of course more elegant, but I guess it boils
down to the same basic idea.
Yep, you need inductive data to guarantee that you eventually stop
spitting out one sort of thing and flip
Has anyone tried out F#?
Is this a taboo subject here?
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Derek Elkins wrote:
Just to add as this was not addressed. -O2 -does not- turn off bounds
checking or any other obvious safety mechanism.
although even just -O removes GHC's special 'assert'ions (unless you
explicitly keep them on?) -- though they shouldn't be used in such a way
that they
I've been meaning to tackle F# as my ML of choice (seeing as I'll need
to get comfortable with .Net, I may as well hit two birds with one
stone).
I've been waiting for the text /Expert F#/ to come out, as it looks
/Foundations of F#/ is pitched towards someone learning their first
functional
I am trying to use Graphics.SOE (that was present at least in GHC 6.4) to
go through Simple Graphics examples as described in Pail Hudak book The
Haskell School of Expression. Learning functional programming through
multimedia.
It looks like Graphics.SOE does not anymore exist in GHC 6.6.1.
Dear,
After a suggestion from quicksilver, I decided to write this message. To
get lambdabot working on 6.6.1 you need to:
1) ensure you have the regexp-base, regexp-compat and regexp-posix from
hackage installed
2) If you install them from user, make sure to add --user in the
build-script of
On Tue, 2007-07-17 at 13:23 +0100, Conor McBride wrote:
On 16 Jul 2007, at 19:53, Stefan Holdermans wrote:
I wrote:
I came up with [...]
apfelmus' solution is of course more elegant, but I guess it boils
down to the same basic idea.
Yep, you need inductive data to guarantee
Tony Morris wrote:
...it seems to be a special case of Set? Does Data.Map add anything more
useful than Map' below?
Besides technical differences, beware that mere convenience makes or
breaks success of tools (languages, libraries).
___
Hello All,
Version 0.3 of Emping is available.
Emping is a utility that reads a table in a csv (comma
separated) format that can be generated from
Open Office Calc (spreadsheet), derives all shortest rules
for a selected attribute, and writes them to a .csv file
that can be read by OO Calc. The
Dmitri O.Kondratiev:
It looks like Graphics.SOE does not anymore exist in GHC 6.6.1.
Where one can get it or what to use instead of it?
You may try Gtk2Hs, which includes an implementation of SOE, called
Graphics.SOE.Gtk. (It works independently of the actual Gtk API.) Use
then the darcs
Hugh Perkins wrote:
Had an idea: a real shootout game for Haskell.
The way it would work is:
- you email a haskell program to a specific address
- it shows up on a web-page
The webpage shows the last submitted solution for each person
- anyone can select two solutions and click Fight
- the
Ben wrote:
a haskell newbie here, searching for comments and wisdom on my code.
i had a project to try to implement external sort in haskell as a
learning exercise. (external sort is sorting a list that is too large
to fit in main memory, by sorting in chunks, spooling to disk, and
then
Hi,
As a struggling newbie, I've started to try various exercises in order
to improve. I decided to try the latest Ruby Quiz
(http://www.rubyquiz.com/quiz131.html) in Haskell. Would someone be kind
enough to cast their eye over my code? I get the feeling there's a
better way of doing it!
I've read tutorials about the syntax of Haskell, but I can't seem to find
any that teach you how to really think in a Haskell way. Is there
anything (books, online tutorials, exercises) that anyone could recommend?
the book The Haskell School of Expression is a good printed resource
in this
On Jul 17, 2007, at 22:26 , James Hunt wrote:
Hi,
As a struggling newbie, I've started to try various exercises in
order to improve. I decided to try the latest Ruby Quiz (http://
www.rubyquiz.com/quiz131.html) in Haskell. Would someone be kind
enough to cast their eye over my code? I get
On 7/17/07, James Hunt [EMAIL PROTECTED] wrote:
As a struggling newbie, I've started to try various exercises in order
to improve. I decided to try the latest Ruby Quiz
(http://www.rubyquiz.com/quiz131.html) in Haskell. Would someone be kind
enough to cast their eye over my code? I get the
Hi James.
I would be tempted to write this a little differently than you did.
First, some of the pieces you've written have equivalents in the
standard library; there's no harm in rewriting them, but I figured I'd
point out that they're there. (Hoogle - haskell.org/hoogle, I believe
- can be a
You hardly ever need to use explicit recursion in Haskell. Every
useful way of doing recursion has already been captured in some
higher order function. For example here is your subarrays
implemented using unfoldr:
subarrays xs = concat $ unfoldr f xs
where
f [] = Nothing
James,
In my earlier post I mentioned that you should find a dynamic
programming approach to this problem. My solution is presented below,
so you've been warned if you are still working this out:
=== READ ABOVE ===
import Data.List (foldl')
solve = snd . foldl' aux (0, 0)
where
aux (cur,
Conor McBride wrote:
Hi all
On 9 Jul 2007, at 06:42, Thomas Conway wrote:
I don't know if you saw the following linked off /.
http://www.itwire.com.au/content/view/13339/53/
[..]
The basic claim appears to be that discrete mathematics is a bad
foundation for computer science. I suspect
On 7/17/07, Martin Coxall [EMAIL PROTECTED] wrote:
I wonder why 'we' aren't pushing things like this big time. When Ruby
took off, more than anything else it was because of Rails. Web
programming is something 'the kids' can really get into, and it caused
Ruby to explode into the mainstream geek
On 7/17/07, Thomas Conway [EMAIL PROTECTED] wrote:
And this is where I think Haskell has it all over C++, Java, and the
rest. Haskell is easy to learn at a simple level, and hard to learn at
the expert level, but once learned is very powerful and has excellent
payoffs in terms of productivity.
On 7/18/07, Hugh Perkins [EMAIL PROTECTED] wrote:
Am I the only person who finds it interesting/worrying that there are few to
no people in the group who are ex-C# programmers. I mean, you could argue
that C# programmers are simply too stupid to do Haskell, but ... you know,
there is another
On 7/18/07, brad clawsie [EMAIL PROTECTED] wrote:
i have wondered what it would take to get a mod_haskell for apache
If you make a mod_haskell, please make sure it's secure. It's insanely hard
to convince web hosting companies to add support for new
mod_myfavoritelanguagehere. If the mod
On Tuesday 17 July 2007 14:53:20 Edward Ing wrote:
Has anyone tried out F#?
Yes. We've been using F# for 9 months now and have several products written in
it.
Is this a taboo subject here?
Probably. ;-)
--
Dr Jon D Harrop, Flying Frog Consultancy Ltd.
OCaml for Scientists
On Wed, Jul 18, 2007 at 12:35:23AM +0200, Hugh Perkins wrote:
If you make a mod_haskell, please make sure it's secure. It's insanely
hard to convince web hosting companies to add support for new
mod_myfavoritelanguagehere.
i personally don't have any plans on creating mod_haskell, it is
[EMAIL PROTECTED]:~/ProjectRepos/learning$ ghc -fglasgow-exts -e 'main'
maxSubArrays.hs
should be [2,5,-1,3]:
[2,5,-1,3]
[EMAIL PROTECTED]:~/ProjectRepos/learning$ cat maxSubArrays.hs
import Data.List
-- maximum sub-array: [2, 5, -1, 3]
main = do putStrLn $ should be ++ show [2, 5, -1, 3] ++ :
Bjorn Bringert wrote:
import Data.List
maxsubarrays xs = maximumBy (compare `on` sum)
[zs | ys - inits xs, zs - tails ys]
I love this solution: simple, understandable, elegant.
As a nit, I might take out the ys and zs names, which obscure the fact
that there is a hidden symmetry in the
On Wed, Jul 18, 2007 at 12:17:12AM +0200, Hugh Perkins wrote:
On 7/17/07, Martin Coxall [EMAIL PROTECTED] wrote:
I wonder why 'we' aren't pushing things like this big time. When Ruby
took off, more than anything else it was because of Rails.
i agree that web programming is a domain that
I also commented out arrows as a dependency in the .cabal, I think.
Was that not a good idea? it seemed to work.
Shachaf
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On Jul 18, 2007, at 0:27 , brad clawsie wrote:
On Wed, Jul 18, 2007 at 12:17:12AM +0200, Hugh Perkins wrote:
On 7/17/07, Martin Coxall [EMAIL PROTECTED] wrote:
I wonder why 'we' aren't pushing things like this big time. When
Ruby
took off, more than anything else it was because of Rails.
on, which will appear in Data.Function in the next release of base,
is defined thusly:
on :: (b - b - c) - (a - b) - a - a - c
(*) `on` f = \x y - f x * f y
You can also use Data.Ord.comparing, in this case -- comparing is just
(compare `on`).
From Ord.hs:
-- |
-- comparing p x y =
Nicest. I think your definition has reached nirvana.
I think a good haskell-cafe thread is like a Shakespeare play. People at
every level of experience can get something from it. The early replies
answer the question, with follow-on ones exploring the roads less
traveled. I for one did not
On Tuesday 17 July 2007 23:26:08 Hugh Perkins wrote:
Am I the only person who finds it interesting/worrying that there are few
to no people in the group who are ex-C# programmers. I mean, you could
argue that C# programmers are simply too stupid to do Haskell, but ... you
know, there is
On Jul 17, 2007, at 7:10 PM, Bjorn Bringert wrote:
Nice. Here's a pointless version:
Good Freudian slip.
maxsubarrays = maximumBy (compare `on` sum) . (= tails) . inits
For the monadically-challenged, this is equivalent, yes-no?
maxsubarrays = maximumBy (compare `on` sum) . concat .
On Jul 18, 2007, at 1:00 , Dan Weston wrote:
Bjorn Bringert wrote:
import Data.List
maxsubarrays xs = maximumBy (compare `on` sum)
[zs | ys - inits xs, zs - tails ys]
I love this solution: simple, understandable, elegant.
As a nit, I might take out the ys and zs names, which obscure the
For the monadically-challenged, this is equivalent, yes-no?
maxsubarrays = maximumBy (compare `on` sum) . concat . (map tails) .
inits
Or: maxsubarrays = maximumBy (compare `on` sum) . concatMap tails . inits
(=) for lists is just (flip concatMap).
Also, this is working with lists, not arrays
| Has anyone tried out F#?
|
| Yes. We've been using F# for 9 months now and have several products
| written in
| it.
|
| Is this a taboo subject here?
| Probably. ;-)
Not at all! But there is a very active F# community that would be much more
knowledgeable about F# than Haskell folk are
On Jul 17, 2007, at 22:26 , James Hunt wrote:
As a struggling newbie, I've started to try various exercises in
order to improve. I decided to try the latest Ruby Quiz (http://
www.rubyquiz.com/quiz131.html) in Haskell.
Haskell guru level: I am comfortable with higher order functions, but
On Wed, 2007-07-18 at 12:13 +1200, ok wrote:
On Jul 17, 2007, at 22:26 , James Hunt wrote:
As a struggling newbie, I've started to try various exercises in
order to improve. I decided to try the latest Ruby Quiz (http://
www.rubyquiz.com/quiz131.html) in Haskell.
What is the trick
ok wrote:
I think it is at least mildly interesting that people commented about
things like whether to do it using explicit parameters (pointful
style) or higher-order functions (pointless style) and whether to
use the list monad or concatMap, but everyone seemed to be happy
with a cubic time
On Wed, 2007-07-18 at 00:26 +0200, Hugh Perkins wrote:
On 7/17/07, Thomas Conway [EMAIL PROTECTED] wrote:
And this is where I think Haskell has it all over C++, Java,
and the
rest. Haskell is easy to learn at a simple level, and hard to
learn at
the
syntactically.vincenz:
Dear,
After a suggestion from quicksilver, I decided to write this
message. To get lambdabot working on 6.6.1 you need to:
1) ensure you have the regexp-base, regexp-compat and
regexp-posix from hackage installed
The .cabal file now enforces this.
shachaf:
I also commented out arrows as a dependency in the .cabal, I think.
Was that not a good idea? it seemed to work.
You just won't be able to use arrows transformers and other fun things
in @eval.
___
Haskell-Cafe mailing list
(Or at least the problem is under-specified.)
1. There may be several sub-sequences having the maximum
sum.
So the type for the solution should be :: Num a = [a] -
[[a]]
(Note that the problem didn't ask for the maximum
itself.)
2. The inits . tails approach adds a fault:
It introduces
Correct, efficient, elegant: you can only have two out of three. I see
where your priorities lie! :)
Dan
Anthony Clayden wrote:
(Or at least the problem is under-specified.)
1. There may be several sub-sequences having the maximum
sum.
So the type for the solution should be :: Num a = [a]
On Jul 17, 2007, at 7:10 PM, Bjorn Bringert wrote:
maxsubarrays = maximumBy (compare `on` sum) . (= tails) . inits
Though I avoided using the list monad in the first solution, since
I thought it would make the code less understandable for a beginner.
I felt uncomfortable seeing this. Let
-BEGIN PGP SIGNED MESSAGE-
Hash: SHA1
David F. Place wrote:
The use of = is just an obscure way of saying (flip concatMap).
Correction.
The use of = is a more general way of saying (flip concatMap).
Tony Morris
http://tmorris.net/
-BEGIN PGP SIGNATURE-
Version: GnuPG v1.4.6
On 2007-07-18, Anthony Clayden [EMAIL PROTECTED] wrote:
(Or at least the problem is under-specified.)
2. The inits . tails approach adds a fault:
It introduces a sprinkling of empty sub-sequences. These
have sum zero.
So in case the input list is all negative numbers ...
Why is this a
I'm forwarding this mail, in case anyone might know about the bug.
-- Forwarded message --
From: Hugo Pacheco [EMAIL PROTECTED]
Date: Jul 18, 2007 3:45 AM
Subject: Happy Error
To: [EMAIL PROTECTED]
Hi Simon,
I'm having what I supose ti be a oarsec internal error when trying to
On 7/17/07, Anthony Clayden [EMAIL PROTECTED] wrote:
2. The inits . tails approach adds a fault:
It introduces a sprinkling of empty sub-sequences. These
have sum zero.
So in case the input list is all negative numbers ...
At least the concatMap inits . tails code that I posted also
midfield:
hi folks --
a haskell newbie here, searching for comments and wisdom on my code.
i had a project to try to implement external sort in haskell as a
learning exercise. (external sort is sorting a list that is too large
to fit in main memory, by sorting in chunks, spooling to
I'm sorry, it turned out to be pretty simples.
The error appears when there are references to undefined terminal or
non-terminal productions.
That's it.
Sorry for the messages, at least it might be of some help to someone else.
hugo
On 7/18/07, Hugo Pacheco [EMAIL PROTECTED] wrote:
Hi
hi --
thanks for the useful comments! i will definitely go through them
carefully. unfortunately for this code (but fortunately for me) i
defend my dissertation on monday so i'm a little distracted right
now.
i'm more than happy to donate this code or whatever improvements
happen to it.
midfield:
hi --
thanks for the useful comments! i will definitely go through them
carefully. unfortunately for this code (but fortunately for me) i
defend my dissertation on monday so i'm a little distracted right
now.
i'm more than happy to donate this code or whatever
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