On Tue, 2007-11-27 at 23:11 -0500, Sterling Clover wrote:
On Nov 27, 2007, at 11:34 AM, David Fox wrote:
In that case we need to identify all the groups that the front page
is serving and create separate areas for each, all above the fold
as it were:
1. A sales pitch for new
| If, after investigation (and perhaps checking with Don) you find that
adding bangs makes your program go
| slower, even though the function is in fact strict (otherwise it might go
slower because it's just doing more
| work!) then I'd love to see a test case.
|
| I wonder if this could be
| There may well have been changes to the strictness analyser that make
| some of the bangs (or most) unnecessary now. Also, its very likely
| I didn't check all combinations of strict and lazy arguments for the
| optimal evaluation strategy :)
|
| If it seems to be running consitently faster (and
Ben Franksen [EMAIL PROTECTED] writes:
PS (completely off-topic, sorry): I've been using the collections library
throughout the project I must say it is a lot nicer to work with
I tried to Google for this, and ended up at
http://hackage.haskell.org/trac/ghc/wiki/CollectionClassFramework
Simon Peyton-Jones wrote:
You might think that unnecessary bangs shouldn't lead to unnecessary work --
if GHC knows it's strict *and* you bang the argument, it should still only be
evaluated once. But it can happen. Consider
f !xs = length xs
Even though 'length' will evaluate
Ketil Malde wrote:
Ben Franksen [EMAIL PROTECTED] writes:
PS (completely off-topic, sorry): I've been using the collections library
throughout the project I must say it is a lot nicer to work with
I tried to Google for this, and ended up at
Hello
still, trying to use a database with ghc 6.8.1 - patience running low
however :)
I now have troubles installing HDBC-sqlite3
the build fails like so :
$ runhaskell Setup.lhs build
Preprocessing library HDBC-sqlite3-1.1.3.0...
Utils.hsc:31:33:
error: hdbc-sqlite3-helper.h: No
On Wed, 28 Nov 2007, manu wrote:
Hello,
I'm trying to build diverse packages from Hackage with ghc 6.8.1,
they usually fail to build because of missing language extensions.
Sometimes I am unable to determine the proper name of the extension
missing in .cabal
I tend to slap {- #OPTIONS
On Tue, 2007-11-27 at 18:02 -0800, Don Stewart wrote:
ben.franksen:
Just thought I install the latest version (0.4.0) from hackage and test it.
Build and install went fine, but then it gets strange:
cabal: dist/Conftest.c: openFile: does not exist (No such file or directory)
This
On Tue, 2007-11-27 at 18:38 +, Paul Johnson wrote:
Brandon S. Allbery KF8NH wrote:
However, the IO system truncates [characters] to 8 bits.
Should this be considered a bug?
A design problem.
I presume that its because stdio.h was defined in the days of
ASCII-only strings, and the
apfelmus schrieb:
Benedikt Huber wrote:
So, the Ref deriviation is really nice for sequential updates;
parallel updates on the other hand need some work.
..
While the select part of the Ref is expressed using , I don't know
how the
parallel update can be expressed in terms of combinators. Any
Hello,
Still trying to build hdbc-sqlite3
it appears that the hdbc-sqlite3 package on Hackage is missing the C
header file
It is included with the hdbc-sqlite3 package found at http://
software.complete.org/hdbc-sqlite3/downloads however.
Now I have another pb :
Building
A safer gimmick...
Ben Franksen wrote:
tickWhileDoing :: String - IO a - IO a
tickWhileDoing msg act = do
hPutStr stderr msg hPutChar stderr ' ' hFlush stderr
start_time - getCPUTime
tickerId - forkIO ticker
... an async exception here will leave the ticker runnning
res -
Hello
I should think a bit before posting to the list, sorry for the
pollution !
this error :
Database/HDBC/Sqlite3/Utils.hsc:74:8: parse error on input `import'
manu:/Volumes/data/Downloads/HDBC/hdbc-sqlite3 manu$
can be avoided by adding ForeignFunctionInterface to the extensions
in
Sebastian Sylvan:
primes :: [Integer]
primes = 2 : filter (null . primeFactors) [3,5..]
primeFactors :: Integer- [Integer]
primeFactors n = factor n primes
where
factor m (p:ps) | p*p m= []
| m `mod` p == 0 = p : factor (m `div` p) (p:ps)
On Nov 28, 2007 12:12 PM, Kalman Noel [EMAIL PROTECTED] wrote:
Sebastian Sylvan:
primes :: [Integer]
primes = 2 : filter (null . primeFactors) [3,5..]
primeFactors :: Integer- [Integer]
primeFactors n = factor n primes
where
factor m (p:ps) | p*p m= []
Josh Lee wrote:
On Tue, 27 Nov 2007 14:41:59 -0500
Isaac Dupree [EMAIL PROTECTED] wrote:
Henning Thielemann wrote:
On Mon, 26 Nov 2007, Jason Dusek wrote:
Among numeric types, it seems that only integer types are Bounded.
Maybe because IEEE format supports Infinity?
therefore, maxBound is
On 28/11/2007, Ben Franksen [EMAIL PROTECTED] wrote:
It was fun, too. For instance, the OP's question reminded me of a little
generic wrapper I wrote -- more or less for my own amusement -- during the
course of this project. It outputs dots during an operation that might take
a little longer
ubuntu gutsy
ghc-6.8.1
HDBC-1.1.3$ runghc Setup.lhs build
Preprocessing library HDBC-1.1.3...
Building HDBC-1.1.3...
[3 of 6] Compiling Database.HDBC.Types ( Database/HDBC/Types.hs,
dist/build/Database/HDBC/Types.o )
Database/HDBC/Types.hs:208:0:
Illegal polymorphic or qualified type:
put
{-# OPTIONS_GHC -fglasgow-exts #-}
at the the top of the file that complains.
Jim Stuttard [EMAIL PROTECTED]
Sent by: [EMAIL PROTECTED]
11/28/2007 08:06 AM
Please respond to
[EMAIL PROTECTED]
To
Haskell-Cafe@haskell.org
cc
Subject
[Haskell-cafe] RFI: HDBC-1.1.3 build error
On Wed, Nov 28, 2007 at 09:27:39AM +0100, Thomas Schilling wrote:
Sorry, but are you talking of *one* homepage? This can all go into own
wiki pages that are aimed at certain audiences, but this really can't
all fit on the front page.
I'm reminded of http://www.shiregames.com/shiregames/
We
On Wed, Nov 28, 2007 at 12:08:30PM +0100, Henning Thielemann wrote:
type List = []
Although not wrong, it is not Haskell 98
It's valid Haskell 98 as far as I know.
Advantages of listing the extensions used are
* Cabal knows whether hugs, for example, can compile the package
* Assuming
On 28 Nov 2007, at 13:41, Ian Lynagh wrote:
On Wed, Nov 28, 2007 at 09:27:39AM +0100, Thomas Schilling wrote:
Sorry, but are you talking of *one* homepage? This can all go into
own
wiki pages that are aimed at certain audiences, but this really can't
all fit on the front page.
I'm
[snip]
I recently withdrew from this project and offered up the libs I'd been
working on as they are for a new owner. Didn't get any takers though
(no surprises there!). I've always found the lack of apparent interest
in all this somewhat puzzling myself. It's not as if there's no latent
On Wed, 28 Nov 2007, Robert Dockins wrote:
FWIW, I find the same phenomenon with Edison. I get very little feedback
about it positive or negative; I really have no idea how many people are
using it. I guess people are more willing to roll their own data structures
or use the standard libs.
apfelmus wrote:
Henning Thielemann wrote:
apfelmus wrote:
Back then, I was given the task to calculate some sequence
of numbers which I did in one page of C code. So far so good, but when I
asked the task assigner about his solution, he responded: Ah, this
problem, that's 1 line in Haskell.
On Nov 28, 2007 6:16 PM, Laurent Deniau [EMAIL PROTECTED] wrote:
I can't see how it could be one page of C unless the page is 10 lines
long ;-) The following code is the direct translation of your Haskell
code (except that it prints the result instead of building a list).
a+, ld.
#include
Hi all,
This e-mail may be a bit off topic. My question is more about methods and
algorithms than Haskell. I'm looking for links to methods or tools for
parsing unstructured data.
I'm currently working on data cleaning of a Customer Addresses database.
Addresses are stored as 3 lines of text
Hello
I've spent a few days trying to install all the packages required to
use HaskellDB with either MySQL or SQlite3
(the only 2 DB the host I was thinking about is supporting)
Well, I am giving up ! I seriously regret replacing ghc-6.6 with
ghc-6.8, I didn't expect that building packages
On 11/28/07, Hans van Thiel [EMAIL PROTECTED] wrote:
Have you looked at the Java Rule Engine (I believe JSR 94) and in
particular Jess?
http://herzberg.ca.sandia.gov/
I have no experience with it myself, though, just heard of it.
Regards,
Hans van Thiel
Hi Hans,
Never heard of that
emmanuel.delaborde:
Hello
I've spent a few days trying to install all the packages required to
use HaskellDB with either MySQL or SQlite3
(the only 2 DB the host I was thinking about is supporting)
Well, I am giving up ! I seriously regret replacing ghc-6.6 with
ghc-6.8, I didn't
emmanuel.delaborde:
Hello,
I'm trying to build diverse packages from Hackage with ghc 6.8.1,
they usually fail to build because of missing language extensions.
Sometimes I am unable to determine the proper name of the extension
missing in .cabal
I tend to slap {- #OPTIONS
On Wed, 2007-11-28 at 12:58 -0500, Olivier Boudry wrote:
Hi all,
This e-mail may be a bit off topic. My question is more about methods
and algorithms than Haskell. I'm looking for links to methods or tools
for parsing unstructured data.
I'm currently working on data cleaning of a Customer
Just out of curiosity...
--some getter functions
pVel !(_,vel,_) = vel
pPos !(pos,_,_) = pos
pMass !(!_,!_,!mass) = mass
What does the !(...) buy you? I thought tuples were already strict by
default in patterns (you'd need ~(...) to make them irrefutable), so
isn't the above equivalent to:
On Nov 28, 2007 1:11 PM, manu [EMAIL PROTECTED] wrote:
Hello
I've spent a few days trying to install all the packages required to
use HaskellDB with either MySQL or SQlite3
(the only 2 DB the host I was thinking about is supporting)
Well, I am giving up ! I seriously regret replacing
(...) When it's phrased as truncates to 8
bits it sounds so simple, surely all we need
to do is not truncate to 8 bits right?
The problem is, what encoding should it pick?
UTF8, 16, 32, EBDIC? (...)
One sensible suggestion many people have made
is that H98 file IO should use the locale
On Wed, 2007-11-28 at 20:46 +0100, Ben Franksen wrote:
Don Stewart wrote:
ben.franksen:
cabal: dist/Conftest.c: openFile: does not exist (No such file or
directory)
This one is due to having an out of date cabal. Upgrade to darcs cabal,
then rebuild cabal-install, and things should
Don Stewart wrote:
ben.franksen:
cabal: dist/Conftest.c: openFile: does not exist (No such file or
directory)
This one is due to having an out of date cabal. Upgrade to darcs cabal,
then rebuild cabal-install, and things should go fine.
Ok. So the package is broken in that it doesn't work
On Nov 28, 2007 11:18 AM, Dan Weston [EMAIL PROTECTED] wrote:
Just out of curiosity...
--some getter functions
pVel !(_,vel,_) = vel
pPos !(pos,_,_) = pos
pMass !(!_,!_,!mass) = mass
What does the !(...) buy you? I thought tuples were already strict by
default in patterns (you'd need
I put up a draft page. Feel free to adjust it.
http://haskell.org/haskellwiki/FrontpageDraft
/ Thomas
___
Haskell-Cafe mailing list
Haskell-Cafe@haskell.org
http://www.haskell.org/mailman/listinfo/haskell-cafe
I'm trying to build diverse packages from Hackage with ghc 6.8.1,
they usually fail to build because of missing language extensions.
Sometimes I am unable to determine the proper name of the extension
missing in .cabal
I tend to slap {- #OPTIONS -fglasgow-exts #-} at the top of the
troublesome
On Nov 28, 2007 8:54 PM, Thomas Schilling [EMAIL PROTECTED] wrote:
I put up a draft page. Feel free to adjust it.
http://haskell.org/haskellwiki/FrontpageDraft
Perhaps slightly OT, but while we're discussing the front page. Is
there any way of getting rid of the numbering on the front
On Wed, 2007-11-28 at 21:02 +, Sebastian Sylvan wrote:
On Nov 28, 2007 8:54 PM, Thomas Schilling [EMAIL PROTECTED] wrote:
I put up a draft page. Feel free to adjust it.
http://haskell.org/haskellwiki/FrontpageDraft
Perhaps slightly OT, but while we're discussing the front page.
On Nov 28, 2007 9:30 PM, Thomas Schilling [EMAIL PROTECTED] wrote:
On Wed, 2007-11-28 at 21:02 +, Sebastian Sylvan wrote:
On Nov 28, 2007 8:54 PM, Thomas Schilling [EMAIL PROTECTED] wrote:
I put up a draft page. Feel free to adjust it.
Alex Jacobson wrote:
My original point (refined) was that I'd like a file extension (.ehs)
that defaults to including all extensions that don't change the meaning
of a .hs program but that may cause a small subset of them not to
compile (e.g. ones that use forall as a type variable, foreign as
Olivier Boudry wrote:
Hi all,
This e-mail may be a bit off topic. My question is more about methods and
algorithms than Haskell. I'm looking for links to methods or tools for
parsing unstructured data.
I'm currently working on data cleaning of a Customer Addresses database.
Addresses
After I have spawned a thread with 'forkIO',
how can I check if that thread work has
finished already? Or wait for it?
The best way to do this is using
Control.Exception.finally: (...)
Changing ugly code for bad performance is not
that usual in Haskell code :(
I think you
On Nov 28, 2007 5:07 PM, Maurício [EMAIL PROTECTED] wrote:
Sorry if I sound rude. I just saw a place for a
small joke, and used it. Chris code is pretty
elegant to what it is supposed to do. However,
knowing if a thread has finished is just 1 bit of
information. There's probably a reason why
Sebastian Sylvan wrote:
On Nov 28, 2007 12:12 PM, Kalman Noel [EMAIL PROTECTED] wrote:
Sebastian Sylvan:
primes :: [Integer]
primes = 2 : filter (null . primeFactors) [3,5..]
primeFactors :: Integer- [Integer]
primeFactors n = factor n primes
where
factor m (p:ps) | p*p m
Dan Weston wrote:
Silly or not, if I compile with -threaded, I always link in the
one-liner C file:
char *ghc_rts_opts = -N2;
so I don't have to remember at runtime whether it should run with 2
cores or not. This just changes the default to 2 cores, so I am still
free to run on only one
On 11/28/07, Grzegorz Chrupala [EMAIL PROTECTED] wrote:
You may have better luck checking out methods used in parsing natural
language. In order to use statistical parsing techniques such as
Probabilistic Context Free Grammars ([1],[2] ) the standard approach is to
extract rule probabilities
Andrew Coppin wrote:
Dan Weston wrote:
Silly or not, if I compile with -threaded, I always link in the
one-liner C file:
char *ghc_rts_opts = -N2;
Ah... you learn something useful every day! I was going to ask on IRC
whether there's any way to do this - but now I don't need to bother.
Thomas Schilling wrote:
On Wed, 2007-11-28 at 20:46 +0100, Ben Franksen wrote:
Don Stewart wrote:
ben.franksen:
cabal: dist/Conftest.c: openFile: does not exist (No such file or
directory)
This one is due to having an out of date cabal. Upgrade to darcs cabal,
then rebuild
Michaeljohn Clement wrote:
Andrew Coppin wrote:
First, somebody else wrote this in C:
int n = 2 , m , primesFound = 0;
for( n=0;n MAX_NUMBERS;n++ )
if( prime[n] )
{
primesFound++;
if( primesFound == 10001 )
cout n is the 10001st prime. endl;
Um, I can't *believe* nobody else
In a normal programming language, you might write something like this:
for x = 1 to 100
print x
...do slow complex stuff...
next x
In Haskell, you're more likely to write something like
result k = filter my_weird_condition $ map strange_conversion $
unfoldr ...
That means that
Duncan Coutts wrote:
When it's phrased as truncates to 8 bits it sounds so simple, surely
all we need to do is not truncate to 8 bits right?
The problem is, what encoding should it pick? UTF8, 16, 32, EBDIC? How
would people specify that they really want to use a binary file.
Whatever we change
Am Mittwoch, 28. November 2007 22:31 schrieb Andrew Coppin:
There are problems for which it's important to know how many times a
given prime factor occurs. And there are other problems where it is
merely necessary to know which primes are factors. I would say it's
useful to have *both*
On Wed, Nov 28, 2007 at 05:58:07PM -0500, Thomas Hartman wrote:
maybe Debug.Trace? like...
import Debug.Trace
t = foldr debugf 0 [1..1]
f :: Int - Int - Int
f = (+)
-- same typesig as f
debugf :: Int - Int - Int
debugf x y | y `mod` 1000 == 0 = x + (trace (show y) y)
debugf x
On Nov 28, 2007 9:28 PM, Andrew Coppin [EMAIL PROTECTED] wrote:
Michaeljohn Clement wrote:
Andrew Coppin wrote:
First, somebody else wrote this in C:
int n = 2 , m , primesFound = 0;
for( n=0;n MAX_NUMBERS;n++ )
if( prime[n] )
{
primesFound++;
if( primesFound == 10001 )
On Nov 28, 2007, at 16:28 , Andrew Coppin wrote:
Michaeljohn Clement wrote:
Andrew Coppin wrote:
First, somebody else wrote this in C:
int n = 2 , m , primesFound = 0;
for( n=0;n MAX_NUMBERS;n++ )
if( prime[n] )
{
primesFound++;
if( primesFound == 10001 )
cout n is the 10001st
Brad Clow:
When I (deeply) force the worker thread's results to be strict, I
observe both cores working, but the execution time (elapsed) slower.
I can only speculate, but since you emphasise deep forcing, I wonder how
deep is the structure returned from the worker thread? Could it be deep
* Static typing, which increases robustness by allowing the
compiler to catch many common errors automatically.
* Type inference, which deduces types automatically and frees
the programmer from writing superfluous type signatures.
* Higher order functions, polymorphism, and
Hi,
'takeMVar' documentation says if there are
multiple threads blocked in takeMVar, and the
MVar becomes full, only one thread will be
woken up.
Since 'takeMVar' is a reading function, i.e.,
it doesn't change the value of the
variable, why waking up only one thread? If
we wake multiple
Well I'd say none of the packages I've tried, build out of the box...
I'm not a windows developer, but
Is it actually reasonable to expect any cabal packages that depend on
external c libraries and headers to build out of the box on windows? How
can cabal find out where those files are,
SevenThunders wrote:
The new behavior is that under certain conditions a certain matrix inner
product produces undefined floats, that should not be there.
I now have a simple example that I have posted as ticket number 1944 for ghc
6.8.1. The behavior is that if I link to an
On 11/28/07, Tim Docker [EMAIL PROTECTED] wrote:
Well I'd say none of the packages I've tried, build out of the box...
I'm not a windows developer, but
Is it actually reasonable to expect any cabal packages that depend on
external c libraries and headers to build out of the box on
I was talking to a few people about this on #haskell, and it was
suggested I ask here. I should say that I'm playing around here; don't
mistake this for an urgent request or a serious problem.
Suppose I wanted to implement automatic differentiation of simple
functions on real numbers; then
I'll repeat, just for the heck of it, that what I want is a type
something like:
diff :: forall A a. (A : Floating, A a) =
(forall b. A b = b - b) - b - b
where A is quantified over all type classes, and : denotes is a
superclass of. The syntax is made up, of course, and
Hi
Thanks for the explanation. I would be grateful for some examples
accompanying the text. I will indicate the right places for real life
(Haskell code) examples in the paragraphs below:
PJ: As I understand it, the distinction is between the mathematical
term non-strict and the
On Nov 29, 2007 4:02 AM, Chris Smith [EMAIL PROTECTED] wrote:
I was talking to a few people about this on #haskell, and it was
suggested I ask here. I should say that I'm playing around here; don't
mistake this for an urgent request or a serious problem.
Suppose I wanted to implement
On Nov 29, 2007 4:31 AM, Luke Palmer [EMAIL PROTECTED] wrote:
On Nov 29, 2007 4:02 AM, Chris Smith [EMAIL PROTECTED] wrote:
I was talking to a few people about this on #haskell, and it was
suggested I ask here. I should say that I'm playing around here; don't
mistake this for an urgent
On Nov 29, 2007 4:23 AM, PR Stanley [EMAIL PROTECTED] wrote:
PRS: You would also get different results - e.g.
let a = 3, b = 7, c = 2
therefore 20 = strict ( ( (a+(b*c)) )
therefore 17 = non-strict ( (a+(b*c)) )
or am I misunderstanding the
The question I asked is about how to type the differentiation function.
Whether the function is correct is a different question, which I'm happy
to talk about; but understand that it's just an example I was playing
with.
Luke Palmer wrote:
Oh, I think I totally missed the point. I missed
Luke Palmer wrote:
I don't see why this should be true. Int - Int is an instance of this type,
but derivatives require limits, which integers don't have. Do you intend to
output the difference sequence of the function in this case?
But then Double - Double is also an instance of this type.
The message I actually receive is:
runhaskell Setup.lhs build
.
./Haq.hs:6:7:
Could not find module `System.Environment':
it is a member of a package base, which is hidden
BTW I haven't actually checked source in via darcs due to cygwin $PATH
problems ...
vasya
On Nov
Hello,
I trying to get a library to build ... I am following the instructions
in http://en.wikibooks.org/wiki/Haskell/Packaging. Under the Build your
project section in this web page, when I try to do an actual build
(runhaskell Setup.lhs build), the imported module System.Environment
Hi
Thanks for the response.
JCC: In most languages, if you have some expression E, and when the
computer attempts to evaluate E it goes in to an infinite loop, then
when the computer attempts to evaluate the expression f(E), it also
goes into an infinite loop, regardless of what f is. That's
Maurício wrote:
Hi,
'takeMVar' documentation says if there are
multiple threads blocked in takeMVar, and the
MVar becomes full, only one thread will be
woken up.
Since 'takeMVar' is a reading function, i.e.,
it doesn't change the value of the
variable, why waking up only one thread? If
we
Hello Andrew,
Thursday, November 29, 2007, 1:11:38 AM, you wrote:
IMHO, someone should make a full proposal by implementing an alternative
System.IO library that deals with all these encoding issues and
implements H98 IO in terms of that.
We need two seperate interfaces. One for text-mode
On Thu, 29 Nov 2007, Ben Franksen wrote:
Thomas Schilling wrote:
I put up a draft page. Feel free to adjust it.
http://haskell.org/haskellwiki/FrontpageDraft
I like the current version better. It is /very/ difficult to pack in such a
short paragraph a list of the most important
On 29 Nov 2007, at 06:32, PR Stanley wrote:
Hi
Thanks for the response.
JCC: In most languages, if you have some expression E, and when the
computer attempts to evaluate E it goes in to an infinite loop, then
when the computer attempts to evaluate the expression f(E), it also
goes into
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