Hello Chris,
Tuesday, January 03, 2006, 12:20:26 AM, you wrote:
CK> Einar Kartunen sped up the code using a custom channel implementation.
CK>This increased speed by a factor of over 2. The wiki at
CK> http://haskell.org/hawiki/ChameneosEntry has the latest version.
can these channels be
Hello
the following code can't go through typechecking. can anyone help me
to fix it or, better, let me know what i need to read to fix it myself? :)
import Control.Monad.ST
import Data.Array.ST
main = print $ runST $
do arr <- newArray (1,10) 127
a <- readArray arr 1
... for the same reason as this one doesn't get through:
import Control.Monad.ST
import Data.Array.ST
main = print $ runST $
do return ()
... but this one does:
import Control.Monad.ST
import Data.Array.ST
main = print $ runST (
do return ())
it's all about rank-2 types; s
Bulat Ziganshin wrote:
the following code can't go through typechecking
> import Control.Monad.ST
> import Data.Array.ST
> main = print $ runST $
>do arr <- newArray (1,10) 127
> a <- readArray arr 1
> writeArray arr 1 216
> b <- readArray arr
Bulat Ziganshin wrote:
> Hello Chris,
>
> Tuesday, January 03, 2006, 12:20:26 AM, you wrote:
>
> CK> Einar Kartunen sped up the code using a custom channel implementation.
> CK>This increased speed by a factor of over 2. The wiki at
> CK> http://haskell.org/hawiki/ChameneosEntry has the la
Hi,
I am relatively new to Haskell and am finding i/o difficult to work
with. I am trying to do something like the following:
I have a file of data, each line of which looks like this:
, INTEGER SEQUENCE
for example:
FOO ,2,1,4,3,6,7,5,9,10,11,8,13,12,
I would like to write a function the read
Hi Robert,
The first thing to mention is that Haskell uses linked-lists, not
arrays as the "standard" list type structure, so [1,2] is actually a
linked list.
The next thing to note is that Haskell is *lazy*. It won't do work
that it doens't have to. This means that you can return a linked list
w
It seems like the real difference between TChan and the Ch code below
is that TChan is, basically, [TVar a] whereas Ch is MVar [a], plus
the order is guaranteed for a TChan.
Now why would it matter so much speed-wise?
This is the CVS code. newTChanIO is exported but undocumented in GHC
6.4
[ Deeply nested replies are starting to look similar to runListT $
runStateT $ runWriter ]
[EMAIL PROTECTED] wrote:
> On Tue, Jan 03, 2006 at 12:07:43AM +, Joel Reymont wrote:
>
>>On Jan 2, 2006, at 9:20 PM, Chris Kuklewicz wrote:
>>
>>
>>> This makes me ponder one of the things that Joe
The other thing to mention, is that if you have the ability to change
file formats, it may be better to make just a slight adjustment... If
you make it look exactly like the haskell data structure you want:
[("Foo", [1,2,3,4,5,6,7])
,("Bar", [7,6,5,4,3,2,1])
,...]
Then your parser becomes ev
Joel Reymont wrote:
> It seems like the real difference between TChan and the Ch code below
> is that TChan is, basically, [TVar a] whereas Ch is MVar [a], plus the
> order is guaranteed for a TChan.
>
> Now why would it matter so much speed-wise?
STM* is usually slower than IO/MVar. STM has t
I asked the Erlang guys why I can log to a single process in Erlang
without any problems. The scheduler could well be round-robin
but since the message queue is hard-wired to each Erlang process
they found an elegant way out.
--
There is a small fix in the scheduler for the standard
producer/cons
Tomasz Zielonka wrote:
On Thu, Dec 29, 2005 at 01:20:41PM +, Joel Reymont wrote:
Why does it take a fraction of a second for 1 thread to unpickle and
several seconds per thread for several threads to do it at the same
time? I think this is where the mistery lies.
Have you considered a
On Jan 3, 2006, at 2:30 PM, Simon Marlow wrote:
The default context switch interval in GHC is 0.02 seconds,
measured in CPU time by default. GHC's scheduler is stricly round-
robin, so therefore with 100 threads in the system it can be 2
seconds between a thread being descheduled and schedul
On 1/3/06, Simon Marlow <[EMAIL PROTECTED]> wrote:
> Tomasz Zielonka wrote:
> > On Thu, Dec 29, 2005 at 01:20:41PM +, Joel Reymont wrote:
> >
> >>Why does it take a fraction of a second for 1 thread to unpickle and
> >>several seconds per thread for several threads to do it at the same
> >>time
General follow-up questions:
Would adding Control.Concurrent.yield commands cause a context switch
more often than every 0.02 seconds?
Is there any command in GHC to allow a thread to prevent itself from
being rescheduled while computing something?
Another comment: between 1000's of threads and
On 03 January 2006 15:13, Joel Reymont wrote:
> On Jan 3, 2006, at 2:30 PM, Simon Marlow wrote:
>> The default context switch interval in GHC is 0.02 seconds,
>> measured in CPU time by default. GHC's scheduler is stricly round-
>> robin, so therefore with 100 threads in the system it can be 2
>>
On 03 January 2006 15:37, Sebastian Sylvan wrote:
> On 1/3/06, Simon Marlow <[EMAIL PROTECTED]> wrote:
>> Tomasz Zielonka wrote:
>>> On Thu, Dec 29, 2005 at 01:20:41PM +, Joel Reymont wrote:
>>>
Why does it take a fraction of a second for 1 thread to unpickle
and several seconds per
On 1/3/06, Simon Marlow <[EMAIL PROTECTED]> wrote:
> On 03 January 2006 15:37, Sebastian Sylvan wrote:
>
> > On 1/3/06, Simon Marlow <[EMAIL PROTECTED]> wrote:
> >> Tomasz Zielonka wrote:
> >>> On Thu, Dec 29, 2005 at 01:20:41PM +, Joel Reymont wrote:
> >>>
> Why does it take a fraction of
Simon,
I don't think CPU usage is the issue. An individual thread will take
a fraction of a second to deserialize a large packet. The issue is
that, as you pointed out, you can get alerts even with 50 threads.
Those fractions of a second add up in a certain way that's
detrimental to the p
Hello,
I've been studying more Haskell and I've improved a lot. But I just hit
a small problem. I want to print all the elements of a linst (putStr).
I'd like to write something like this:
print_list [] = do putStr ""
print_list (x:xs) = (do putStr x) && print_list xs
I know this is wrong, b
Thanks for the answer, but I should I written a longer comment. I have
added such a longer comment below:
Simon Marlow wrote:
> Chris Kuklewicz wrote:
>
>> Another comment: between 1000's of threads and writing a custom
>> continuation based scheduler, what about using a thread pool? Does
>> any
Daniel Carrera wrote:
print_list xs = do putStr(join xs)
where join [] = ""
join (x:xs) = (show x) ++ "\n" ++ join xs
print_list xs = mapM putStrLn xs
Question: What do you call a function that has side-effects? (like
putStr) I know that "function" is the wrong term.
"action",
Daniel Carrera wrote:
> Hello,
>
> I've been studying more Haskell and I've improved a lot. But I just hit
> a small problem. I want to print all the elements of a linst (putStr).
> I'd like to write something like this:
>
> print_list [] = do putStr ""
> print_list (x:xs) = (do putStr x) && prin
Hi,
All Haskell functions are lazy, hence there is no need to "write a
lazy version" of your print_list function. I think the function you
probably want is:
putStr (unlines xs)
This uses the bulid in unlines function, which is similar in spirit to
join (you get more quotes, which I guess you don
On Tuesday 03 Jan 2006 5:37 pm, Christian Maeder wrote:
> Daniel Carrera wrote:
>
> > Question: What do you call a function that has side-effects? (like
> > putStr) I know that "function" is the wrong term.
>
> "action", "command", "program", etc.
Actually (at the risk of appearing pedantic), I th
On 1/3/06, Daniel Carrera <[EMAIL PROTECTED]> wrote:
> Hello,
>
> I've been studying more Haskell and I've improved a lot. But I just hit
> a small problem. I want to print all the elements of a linst (putStr).
> I'd like to write something like this:
>
> print_list [] = do putStr ""
> print_list (
Sebastian Sylvan wrote:
Others have already replied with a solution, but it looks to me like
what you're "missing" is how to sequence commands, which is the whole
purpose of the "do" notation.
print_list [] = return ()
print_list (x:xs) =
do putStr x
print_list xs
The do notation is us
Chris Kuklewicz wrote:
What does lazy printing mean?
I assume it means you evaluate the head of the list, print it, then
recursively do this for the tail of the list. With an infinite list you
will get inifinite output.
I assume it does not mean you evaluate the whole list before printing
anyt
On Tue, 3 Jan 2006, Chris Kuklewicz wrote:
...
> I sometimes call a function with side-effects in IO a "command". But
> the terms are fungible. But calling putStr a "function" is correct. It
> is not a "pure function" however.
Is that the standard party line? I mean, we all know its type and
s
Neil Mitchell wrote:
All Haskell functions are lazy, hence there is no need to "write a
lazy version" of your print_list function. I think the function you
probably want is:
putStr (unlines xs)
Hhmm... that does work, and I'm a bit surprised that it does. I guess
I'm still stuck in the eager
On 1/3/06, Daniel Carrera <[EMAIL PROTECTED]> wrote:
> Neil Mitchell wrote:
> > All Haskell functions are lazy, hence there is no need to "write a
> > lazy version" of your print_list function. I think the function you
> > probably want is:
> >
> > putStr (unlines xs)
>
> Hhmm... that does work, an
On Tuesday 03 Jan 2006 6:11 pm, Donn Cave wrote:
> On Tue, 3 Jan 2006, Chris Kuklewicz wrote:
> ...
>
> > I sometimes call a function with side-effects in IO a "command". But
> > the terms are fungible. But calling putStr a "function" is correct. It
> > is not a "pure function" however.
>
> Is t
On Jan 3, 2006, at 6:30 PM, Sebastian Sylvan wrote:
On 1/3/06, Daniel Carrera <[EMAIL PROTECTED]> wrote:
Neil Mitchell wrote:
All Haskell functions are lazy, hence there is no need to "write a
lazy version" of your print_list function. I think the function you
probably want is:
putStr (unline
On 03/01/06, Donn Cave <[EMAIL PROTECTED]> wrote:
> On Tue, 3 Jan 2006, Chris Kuklewicz wrote:
> ...
> > I sometimes call a function with side-effects in IO a "command". But
> > the terms are fungible. But calling putStr a "function" is correct. It
> > is not a "pure function" however.
>
> Is th
I've just been through the process of converting some code from using
Control.Exception to
using an Error monad, and I would recommend that as a more straightforward and
manageable alternative, unless you need Control.Exception for other reasons.
I started by changing my potentially-failing fun
On Tue, Jan 03, 2006 at 02:30:53PM +, Simon Marlow wrote:
> I measured the time taken to unpickle those large 50k packets as 0.3
> seconds on my amd64 box (program compiled *without* optimisation), so
> the thread can get descheduled twice during while unpickling a large
> packet, giving a >
Joel,
In most cases, it just doesn't make sense to run 1000 threads
simultaneously that are all bottlenecked on the same resource (e.g.
CPU/memory) See e.g. http://www.eecs.harvard.edu/~mdw/proj/seda/
You should be grouping incoming events into queues by expected
workload/event. Then you ca
On Tue, Jan 03, 2006 at 05:49:07PM +, Neil Mitchell wrote:
> All Haskell functions are lazy, hence there is no need to "write a
> lazy version" of your print_list function. I think the function you
> probably want is:
>
> putStr (unlines xs)
>
> This uses the bulid in unlines function, which
Hello,
Where there were no entries to the
http://shootout.alioth.debian.org/benchmark.php?test=chameneos&lang=all
benchmark, there are now two. The one by Josh Goldfoot is already
posted, the one Einar Karttunen and I optimized has been submitted and
will run faster/smaller. Our code is at
htt
Daniel Carrera wrote:
> I've been studying more Haskell and I've improved a lot. But I just hit
> a small problem. I want to print all the elements of a linst (putStr).
> I'd like to write something like this:
>
> print_list [] = do putStr ""
This looks as if you're confused. The keyword "do"
Neil and Thomas,
Thanks to both of you for your help. I have things working now.
Bob
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The timeleak code is just a repro case. In real life I'm reading from
sockets as opposed to a file.
All I'm trying to do is run poker bots. They talk to the server and
play poker. Of course some events are more important than others, a
request to make a bet is more important than, say, a ta
On Tue, Jan 03, 2006 at 04:36:37PM -, Simon Marlow wrote:
> > Is it impractical then to implement this type of app in Haskell?
> > Based on the nature of Haskell scheduling I would be inclined to say
> > yes.
>
> Absolutely not!
>
> Apart from the problem you have with a space leak caused by
On 1/3/06, Chris Kuklewicz <[EMAIL PROTECTED]> wrote:
> Hello,
>
> Where there were no entries to the
> http://shootout.alioth.debian.org/benchmark.php?test=chameneos&lang=all
> benchmark, there are now two. The one by Josh Goldfoot is already
> posted, the one Einar Karttunen and I optimized ha
On 1/3/06, Sebastian Sylvan <[EMAIL PROTECTED]> wrote:
> On 1/3/06, Chris Kuklewicz <[EMAIL PROTECTED]> wrote:
> > Hello,
> >
> > Where there were no entries to the
> > http://shootout.alioth.debian.org/benchmark.php?test=chameneos&lang=all
> > benchmark, there are now two. The one by Josh Goldf
Am Dienstag, 3. Januar 2006 19:15 schrieb Daniel Carrera:
> Neil Mitchell wrote:
> > All Haskell functions are lazy, hence there is no need to "write a
> > lazy version" of your print_list function. I think the function you
> > probably want is:
> >
> > putStr (unlines xs)
>
> Hhmm... that does wor
Discussing the fannkuch entry
Sebastian Sylvan wrote:
> On 1/3/06, Sebastian Sylvan <[EMAIL PROTECTED]> wrote:
>
>>On 1/3/06, Chris Kuklewicz <[EMAIL PROTECTED]> wrote:
>>
>>>Hello,
>>>
>>> And finially, the haskel entry for
>>>http://shootout.alioth.debian.org/benchmark.php?test=fannkuch&lang=al
On 03/01/06, Sebastian Sylvan <[EMAIL PROTECTED]> wrote:
> On 1/3/06, Sebastian Sylvan <[EMAIL PROTECTED]> wrote:
> > On 1/3/06, Chris Kuklewicz <[EMAIL PROTECTED]> wrote:
> > > Hello,
> > >
> > > Where there were no entries to the
> > > http://shootout.alioth.debian.org/benchmark.php?test=chamen
On 03/01/06, Cale Gibbard <[EMAIL PROTECTED]> wrote:
> I managed to do better with the following program which gets the
> following time report on my machine
> real0m8.175s
> user0m7.742s
> sys 0m0.186s
> as opposed to
> real0m23.232s
> user0m21.115s
> sys 0m0.077s
> for the
Hello,
Here is a short (16 lines) and readable Haskell'98 solution.
I haven't optimized it or tested it much.
When compiled with ghc(6.4.1) -O2, it takes about 10s to compute the
answer for 9,
on my P3 366MHz machine. It seems to use about 16K of memory.
-Iavor
import System(getArgs)
flop xs@(x:
I took a quick crack at optimizing fannkuch.hs. I got it down from 33s to
1.25s on my machine, with N=9. That should put it between forth and
ocaml(bytecode) in the shootout page. The main changes I made were using
Int instead of Int8, foldl' to accumulate the max number of folds, a
custom f
On 1/3/06, Chris Kuklewicz <[EMAIL PROTECTED]> wrote:
> Hello,
>
> Where there were no entries to the
> http://shootout.alioth.debian.org/benchmark.php?test=chameneos&lang=all
> benchmark, there are now two. The one by Josh Goldfoot is already
> posted, the one Einar Karttunen and I optimized ha
On Sun, Jan 01, 2006 at 11:12:31PM +, Joel Reymont wrote:
> Simon,
>
> Please see this post for an extended reply:
>
> http://wagerlabs.com/articles/2006/01/01/haskell-vs-erlang-reloaded
Looking at this code, I wonder if there are better ways to express
what you really want using static typi
On Wed, Jan 04, 2006 at 03:02:29AM +0100, Sebastian Sylvan wrote:
> I took a stab at the rev-comp one due to boredom. It's not a space
> leak, believe it or not, it's *by design*...
>
> My god, I think someone is consciously trying to sabotage Haskell's
> reputation!
>
> Instead of reading input
On 1/4/06, Sebastian Sylvan <[EMAIL PROTECTED]> wrote:
> On 1/3/06, Chris Kuklewicz <[EMAIL PROTECTED]> wrote:
> > Hello,
> >
> > Where there were no entries to the
> > http://shootout.alioth.debian.org/benchmark.php?test=chameneos&lang=all
> > benchmark, there are now two. The one by Josh Goldf
Keep in mind that the shootout requires that the first 30 permutations printed
out by the Fannkuch benchmark to be exactly those given in the "example." Any
other order of permutations gets your code labeled "Error" by the shootout
administrators. See the discussion here:
http://alioth.debian
I was surprised to learn that indexed insertion:
permutations (x:xs) =
[insertAt n x perms | perms <- permutations xs,
n <- [0..length xs] ]
insertAt :: Int -> a -> [a] -> [a]
insertAt 0 y xs = y:xs
insertAt n y (x:xs) = x:(insertAt (n-1) y xs)
was faster than the
On Tue, Jan 03, 2006 at 10:28:54PM +0100, Udo Stenzel wrote:
> Daniel Carrera wrote:
> > print_list [] = do putStr ""
>
> This looks as if you're confused. The keyword "do" is completely
> redundant. "do" does not mean "please ignore all rules and allow side
> effects", it rather means "please b
Donn Cave wrote:
> > I sometimes call a function with side-effects in IO a "command". But
> > the terms are fungible. But calling putStr a "function" is correct. It
> > is not a "pure function" however.
>
> Is that the standard party line? I mean, we all know its type and
> semantics, whatev
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