Dan Piponi wrote:
If you allow me to play Devil's advocate for a moment...just don't let
this guy ask you how long the Haskell version takes.
In fact, you can borrow a trick from the C++ version. Try this instead:
import Data.Set
main = interact $ unlines . toList . fromList . words
Yes - I
Rodrigo Queiro wrote:
group collects equal elements in sublists. Thus, unique can be
implemented as:
unique = map head . group
i.e. taking the first of each group of equal elements.
(Yet) another way of doing this, is a modified quicksort:
qsort [] = []
qsort (x:xs) = qsort (filter (x) xs) ++
Greetings.
I have just implemented a heap. But... um... I can't acutally figure out
*which kind* of heap it is! LOL. Any ideas?
(Seems to work really well, whatever it is. Oh, and I discovered that
you can sort data just by shoving it all into a heap, and then taking it
all out again.
andrewcoppin:
Hi everybody.
Is there any circumstances under which an expression like map (2*) would
perform an in-place update rather than generating a new list? (Obviously
Yes, should be fine, if the result is consumed. We have fusion
frameworks that do this.
this depends on which
Hello All,
Defining a partially ordered set as:
data Porder = HI | LW | NT deriving (Eq)
class (Eq a) = Poset a where
pcompare :: a - a - Porder
and defining an instance for type synonym RuRe:
type RuRe = ([Int],[Int])
instance Poset RuRe where
pcompare (x1,y1) (x2,y2)
On Sat, 2007-05-19 at 15:30 +0100, David House wrote:
On 19/05/07, Hans van Thiel [EMAIL PROTECTED] wrote:
causes no problems in Hugs (-98 flag) but compiling with GHC produces:
There's the solution to your problem: type synonym instances aren't
Haskell98, so you have to pass the -98 flag
On 19/05/07, Andrew Coppin [EMAIL PROTECTED] wrote:
Um... why doesn't this work?
my_fn x = do
if x 0
then do
let y = 5
return ()
else do
let y = 8
return ()
print y
(Error: y is not in scope.)
let-blocks only scope over the do-block they're contained in.
David House wrote:
On 19/05/07, Andrew Coppin [EMAIL PROTECTED] wrote:
Um... why doesn't this work?
my_fn x = do
if x 0
then do
let y = 5
return ()
else do
let y = 8
return ()
print y
(Error: y is not in scope.)
let-blocks only scope over the do-block
On 19/05/07, Andrew Coppin [EMAIL PROTECTED] wrote:
How about this?
do
y - if x 0
then do ...
else do ...
As with many other things in Haskell, the rule is Give it a go and
see if it works! You should find that the above code runs fine.
--
-David House, [EMAIL PROTECTED]
David House [EMAIL PROTECTED] writes:
On 18/05/07, Albert Y. C. Lai [EMAIL PROTECTED] wrote:
Lazy evaluation says, to evaluate x, call f first, then x is the last
call.
x may be the last to be evaluated, but you still have to pass through
f's call context 'on the way out'.
Not exactly,
On Sat, May 19, 2007 at 04:10:29PM +0100, Jon Fairbairn wrote:
[...]
foldl f z l = case l of
(x:xs) - foldl f (f z x) xs
[] - z
which reveals that foldl in the RHS isn't really the
leftmost outermost function, but case is -- the tail call is
to case. It
I just switched to OS X and was wondering if someone would like to
share their setup. Install binaries from haskell.org or Mac Ports?
Which emacs build? etc
Johan
___
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I use Aquamacs with the haskell mode from haskell.org. MacPorts
wasn't being useful with ghc, I downloaded binaries, and they work
fine.
On 5/19/07, Johan Tibell [EMAIL PROTECTED] wrote:
I just switched to OS X and was wondering if someone would like to
share their setup. Install binaries from
Is there a nice way to install the binaries and get the dependencies
while still being able to easily uninstall the stuff (without a
package manager)? What are the dependencies?
On 5/19/07, Tom Harper [EMAIL PROTECTED] wrote:
I use Aquamacs with the haskell mode from haskell.org. MacPorts
MacPorts works fine here, and the maintainer, Gregory Wright, is very
supportive.
If it works for you, I really recommend MacPorts. The only downside
are the lengthy compile times, but this is not a big deal, you can
just leave it installing overnight.
Carbon Emacs flavour here instead of
I've been getting some pretty weird complaints from the type checker.
And I just figured out why! Grr...
Is there any function that does the same thing as until, but in a monad?
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You can define one:
untilM :: Monad m = (a - Bool) - (a - m a) - a - m a
untilM pred f x | pred x = return x
| otherwise = f x = untilM pred f
Matthew Cox
- Original Message -
From: Andrew Coppin
To: haskell-cafe@haskell.org
Sent: Sat, 19 May 2007 19:49:40 +0100
Matthew Cox wrote:
You can define one:
untilM :: Monad m = (a - Bool) - (a - m a) - a - m a
untilM pred f x | pred x = return x
| otherwise = f x = untilM pred f
Matthew Cox
Hey, neat! :-D
Mmm, I wonder if one could use fail to exit the loop instead... Oh,
wait, for some
It occurred to me that the predicate will generally be a monadic function
itself, so here's a
refined version:
:: Monad m = (a - m Bool) - (a - m a) - a - m a
untilM pred f x = do c - pred x
if c then return x
else f x = untilM pred f
Think of a
Hello,
I have written a function f, that performs a quite complex operation on its
argument.
Furthermore I have another function genInput that takes a number and
constructs
an argument for f of this size.
What I want now is a list [(n,time)] that gives me for every size of input n
the time, f
The following doesn't seem to work. Is this a limitation of the current
implementation or will it never work? Are there any work arounds without
introducing extra type params into the data type E?
class G a b | a - b where
data E a :: *
wrap :: b - E a
unwrap :: E a - b
instance
I use the MacPorts package of GHC and Aquamacs (with haskell-mode).
It works quite nicely for me. Fink also seems to have a GHC package,
in case you prefer it.
Aaron
On May 19, 2007, at 11:24 AM, Johan Tibell wrote:
I just switched to OS X and was wondering if someone would like to
share
I previously worked out how to use the monad transformers to make a when /
repeat control structure that admitted both break and continue
statements. It uses a ContT monad transformer to provide the escape semantics
and the Reader to store the continuation.
I'll paste the code here:
-- By
On 5/19/07, Pepe Iborra [EMAIL PROTECTED] wrote:
If it works for you, I really recommend MacPorts. The only downside
are the lengthy compile times, but this is not a big deal, you can
just leave it installing overnight.
Ah, I'm glad you said that. I was wondering if some kind of bit rot
was
Hi
I made a program that detects user presence in a linux box by checking
for keyboard interruptions in /proc/interrupts.
Problem is, it is supposed to run for a long time, and it keeps about
40MB for itself.
Yeah, this is one more help me with this memory problem mails...
The code can
I'd like to share something with you. I call it the evil ***
function from hell:
(Results xss) = f = Results $ map concat $ diagonalise $ map (foldr
longZip [] . map (unpack . f)) xss
If you attempt to comprehend how this function works, you WILL in fact
loose your mind! However, it
Ilya Tsindlekht [EMAIL PROTECTED] writes:
On Sat, May 19, 2007 at 04:10:29PM +0100, Jon Fairbairn wrote:
[...]
foldl f z l = case l of
(x:xs) - foldl f (f z x) xs
[] - z
which reveals that foldl in the RHS isn't really the
leftmost outermost
Hi
I made a program that detects user presence in a linux box by checking
for keyboard interruptions in /proc/interrupts.
Problem is, it is supposed to run for a long time, and it keeps about
40MB for itself.
Yeah, this is one more help me with this memory problem mails...
The code can
Hello,
How do I create a HaXml filter that adds a new element as a child of
an existing element. For example, let's say I have the XML document:
a
b/
c/
/a
How do I add a new element under a / so that I have the document:
a
newElement/
b/
c/
/a
The following works, but it seems very
I think (although I am far from an expert) that it is a skew heap, based on
this: http://www.palgrave.com/pdfs/0333992857.pdf
On 19/05/07, Andrew Coppin [EMAIL PROTECTED] wrote:
Greetings.
I have just implemented a heap. But... um... I can't acutally figure out
*which kind* of heap it is!
On Sat, May 19, 2007 at 09:16:46PM +0100, Jon Fairbairn wrote:
Ilya Tsindlekht [EMAIL PROTECTED] writes:
By definition, tail recursive function is recursive function in which
the value returned from a recursive call is immediately returned without
modification as value of the top-level
On Sat, May 19, 2007 at 05:33:22PM -0300, Leandro Lisboa Penz wrote:
Hi
I made a program that detects user presence in a linux box by checking
for keyboard interruptions in /proc/interrupts.
Problem is, it is supposed to run for a long time, and it keeps about
40MB for itself.
On Sat, May 19, 2007 at 08:40:46PM +0100, Matthew Sackman wrote:
The following doesn't seem to work. Is this a limitation of the current
implementation or will it never work? Are there any work arounds without
introducing extra type params into the data type E?
class G a b | a - b where
matt:
It occurred to me that the predicate will generally be a monadic function
itself, so here's a
refined version:
:: Monad m = (a - m Bool) - (a - m a) - a - m a
untilM pred f x = do c - pred x
if c then return x
else f x = untilM pred f
lpenz:
Hi
I made a program that detects user presence in a linux box by checking
for keyboard interruptions in /proc/interrupts.
Problem is, it is supposed to run for a long time, and it keeps about
40MB for itself.
Yeah, this is one more help me with this memory problem mails...
Steffen Mazanek:
I have written a function f, that performs a quite complex operation on
its
argument.
Furthermore I have another function genInput that takes a number and
constructs
an argument for f of this size.
What I want now is a list [(n,time)] that gives me for every size of
Hi,
I just wanted to announce that Sam Hughes will be taking over as Keeper
of the YAHT.
YAHT is the venerable Yet Another Haskell Tutorial. It is available
both as a wikibook and as a PDF (*).
The Keeper of the YAHT has the grave duty of synchronising the YAHT
wikibook and tex source, and
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