On Mar 17, 2010, at 10:27 PM, Darrin Chandler wrote:
Let's go back to your original code:
data Point = Cartesian (Cartesian_coord, Cartesian_coord)
| Spherical (Latitude, Longitude)
type Center = Point
type Radius = Float
data Shape = Circle Center Radius
Hi,
I was looking at hoogle documentation when I remembered that there is
some nice, but quite unusable, feature of squeak (smalltalk) which
allows you to search function in the library by giving a list of pairs
of inputs/ouputs.
When I'm saying that it is quite unusable, I mean that squeak has
On 18 March 2010 05:48, Brandon S. Allbery KF8NH allb...@ece.cmu.edu wrote:
They can be mixed only with significant effort. And you can't really
prevent it once your users know the magic of existential quantification;
*but* those lists won't typecheck when passed to your routines expecting a
Leksah - 0.8.0.1 rpms for Fedora 12 now available
goog_1268906153764http://leksah.org/download.html
About Leksah:
*Leksah* is the Haskell IDE of choice. It is written in Haskell, uses Gtk,
and runs on Linux, Windows and Mac OS X. Leksah is a practical tool to
support the Haskell development
hi wren
Where I've used it, random access does seem conceptual more
satisfactory than trying to avoid it.
Well designed binary formats are deterministic - so wherever you are
inside the file you should know what you are parsing. One example of
this determinism is that parsing local alternatives
Lakshmi Narasimhan lakshminaras2...@gmail.com writes:
*Leksah* is the Haskell IDE of choice.
Is it? Really?
Whilst some people might find it great to have a Haskell-oriented IDE
(even better to have it written in Haskell), that kind of a statement
demands proof IMHO. I for one don't recall
As Daniel pointed out earlier, this may be of a little bit of help:
http://haskell.org/ghc/docs/latest/html/libraries/base-4.2.0.0/src/Data-List.html#subsequences
On 18 March 2010 04:03, Alexander Solla a...@2piix.com wrote:
On Mar 17, 2010, at 8:33 PM, zaxis wrote:
`allPairs list =
As you may know, community.haskell.org (also hosting code.h.o,
trac.h.o, etc) exists as a resource to enable Haskellers to publish
and collaborate on open source projects.
The current admin team for this virtual host finds itself with a lack
of time (and occasionally expertise) to maintain
Paul Brauner schrieb:
Hi,
I was looking at hoogle documentation when I remembered that there is
some nice, but quite unusable, feature of squeak (smalltalk) which
allows you to search function in the library by giving a list of pairs
of inputs/ouputs.
When I'm saying that it is quite unusable,
Darrin Chandler wrote:
data Point = Cartesian (Cartesian_coord, Cartesian_coord)
| Spherical (Latitude, Longitude)
type Center = Point
type Radius = Float
data Shape = Circle Center Radius
| Polygon [Point]
This obviously stinks since a Polygon could
I was just reading through the discussion, and Tillmann, your reply is one
of the best written descriptions I've ever seen here. (or even in any other
mail list!)
Of course, I see many good replies here, but they almost always turn out to
be irrelevant to the original question. Yours on the other
Sounds great!
Here are a few feature requests:
The I/O pair ([-1,4,-6],[1,4,6]) could yield map abs as a suggestion :)
The pairs ('a',False) and ('*',True) could yield not . isAlpha etc.
I realize that this (at least the composition part) will probably
increase complexity beyond what's
Paul Brauner wrote:
feature [...] to search function in the library by giving a list of pairs
of inputs/ouputs. [...]
But, piggibacking such a feature on top of hoogle would surely be more
efficient:
1. infer types for arguments and outout
2. look for matching functions using google
3.
On Thu, Mar 18, 2010 at 01:49:20PM +0100, Janis Voigtländer wrote:
Paul Brauner schrieb:
Hi,
I was looking at hoogle documentation when I remembered that there is
some nice, but quite unusable, feature of squeak (smalltalk) which
allows you to search function in the library by giving a list
Hi again,
is there a way in some haskell extension to explicit (system F's) big
lambdas and (term Type) applications in order to help type inference?
If not: is there a way to provide ghc directly with core code before
the type checking phase?
Paul
Am Donnerstag 18 März 2010 05:03:28 schrieb Alexander Solla:
On Mar 17, 2010, at 8:33 PM, zaxis wrote:
`allPairs list = [(x,y) | x - list, y - list] ` is not what
`combination`
does !
let allPairs list = [(x,y) | x - list, y - list]
allPairs [1,2,3]
Hi,
I'm not sure if this is the right place to ask because the problem may
lay in my Apache or system configuration.
I use the Apache proxy module to forward a HTTP request from port 80 to
a Happstack application listening on port 8000 via `ProxyPass /
http://localhost:8000/' on Windows XP.
I'm also on Mac Leopard. I tried installing ghc 6.12 with Haskell
Platform 2009.2.9.2-i386.dmg (ghc 6.10.4) for some reason, and ran into
a bunch of problems (problems to me, anyway). I ended up uninstalling 6.12
and reinstalling haskell platform. Uninstall is easy, there is an
uninstaller
Hello!
Nice, Parsec 3 comes with a monad transformer [1]. So I thought I could
use IO as inner monad, and perform IO operations during parsing.
But I failed. Monad transformers still bend my mind. My problem: I
don't see a function to actually lift the IO operation into the
ParsecT. It should be
Stefan Klinger all-li...@stefan-klinger.de writes:
Hello!
Nice, Parsec 3 comes with a monad transformer [1]. So I thought I could
use IO as inner monad, and perform IO operations during parsing.
But I failed. Monad transformers still bend my mind. My problem: I
don't see a function to
Thanks to those who responded. Solutions that didn't work for my
specific case still taught me more about expressing things in the
Haskell type system.
And... this particular response is extremely well written and useful.
You've made the issues involved very clear and understandable. I really
A phantom type might do what you want:
-- notice the type parameter on point that isn't used in the type
data Point a = Cartesian (Cartesian_coord, Cartesian_coord)
| Spherical (Latitude, Longitude)
-- make some dummy types
data SphericalP
data CartesianP
--make some
Hi Paul,
You should be able to introduce \Lambda at the source level by writing
a type signature with an explicit forall. Similarly you can then
instantiate these \Lambdas by using a type signature which is an
instance of the foralled type at the use site:
~~~
-- id will get a \Lambda in Core
id
Am Donnerstag 18 März 2010 04:29:53 schrieb zaxis:
The time is wasted to run combination even if use `combination (x:xs) =
concat [(x:ys), ys] | ys - combination xs] ' instead.
in ghci
combination [1..20]
will wait for a long time ...
Hm, really?
Prelude :set +s
On Thu, Mar 18, 2010 at 10:37 AM, Stefan Klinger
all-li...@stefan-klinger.de wrote:
Hello!
Nice, Parsec 3 comes with a monad transformer [1]. So I thought I could
use IO as inner monad, and perform IO operations during parsing.
But I failed. Monad transformers still bend my mind. My problem:
On 18 March 2010, Gregory Collins wrote with possible deletions:
ParsecT has a MonadIO instance:
class Monad m = MonadIO m where
liftIO :: IO a - m a
Thank you! I didn't see this. Great!
Kind regards,
Stefan
--
Stefan Klinger o/klettern
On Wed, Mar 17, 2010 at 09:20:49PM -0700, Darrin Chandler wrote:
data Point= Cartesian (Cartesian_coord, Cartesian_coord)
| Spherical (Latitude, Longitude)
Just a quick unrelated note, though you are probably aware of this,
doing
data Foo = Foo (X,Y)
means something subtly
On Thu, Mar 18, 2010 at 12:17 PM, John Meacham j...@repetae.net wrote:
On Wed, Mar 17, 2010 at 09:20:49PM -0700, Darrin Chandler wrote:
data Point = Cartesian (Cartesian_coord, Cartesian_coord)
| Spherical (Latitude, Longitude)
Just a quick unrelated note, though you are
On Wed, Mar 17, 2010 at 09:20:49PM -0700, Darrin Chandler wrote:
Trying to get up to speed in Haskell, I'm playing with doing some
abstraction in data types. Specifically, I have this:
type Cartesian_coord = Float
type Latitude = Float
type Longitude = Float
data Point= Cartesian
this will be EASY for you to fix, I am sure... what the heck am I doing wrong:
import System.Environment(getArgs)import
System.Process(readProcessWithExitCode)import System.Exit(exitWith)
main = do args - getArgs (ecode,out,err) - readProcessWithExitCode
c:\\Perl64\\bin\\perl.exe
This compiles:
import System.Environment(getArgs)
import System.Process(readProcessWithExitCode)
import System.Exit(exitWith,ExitCode(ExitSuccess))
main = do
args - getArgs
(ecode,out,err) - readProcessWithExitCode
c:\\Perl64\\bin\\perl.exe (C:\\Program
Files\\MySQL\\scripts\\mysql_config.pl
Hello!
I am trying to implement a binary search function that returns the index of
an
exact or the (index + 1) where the item should be inserted in an array if
the item to be searched is not found (I am not trying to insert data in the
array) .
Right now, the bottleneck of my program is in
Yes, THANKS!! But my other problem was, that once I get it to compile, I get
nothing output:
C:\Program Files\MySQL\binghc --make -o mysql_config.exe main.hs[1 of 1]
Compiling Main ( main.hs, main.o )Linking mysql_config.exe ...
C:\Program Files\MySQL\binmysql_config --libs
Am Donnerstag 18 März 2010 19:59:33 schrieb Arnoldo Muller:
Hello!
I am trying to implement a binary search function that returns the index
of an
exact or the (index + 1) where the item should be inserted in an array
if the item to be searched is not found (I am not trying to insert data
in
Hello,
In order to build (cabal install HDBC-mysql) the HDBC-mysql package, I am
having to make the following changes:
(1) I had to change the mysql (5.1.45 community distrib msi) to use a wrapper
exe on the mysql_config.pl and put this in c:\program files\mysql\bin since
although the
Am Donnerstag 18 März 2010 20:49:30 schrieb Daniel Fischer:
Am Donnerstag 18 März 2010 19:59:33 schrieb Arnoldo Muller:
Hello!
I am trying to implement a binary search function that returns the
index of an
exact or the (index + 1) where the item should be inserted in an array
if the
Hoogle is a great tool for finding haskell functions:
http://www.haskell.org/hoogle/
You can punch in the type of a function you want and it will give you a list
of functions that might do what you need.
Generalizing the types a bit usually helps. Searching for either m a - n m
a or IO a -
Job Vranish wrote:
Hoogle is a great tool for finding haskell functions:
http://www.haskell.org/hoogle/
You can punch in the type of a function you want and it will give you
a list of functions that might do what you need.
Generalizing the types a bit usually helps. Searching for either m a
Daniel Fischer wrote:
If it's called often, and the arrays are 0-based and Int-indexed,
import Data.Array.Base (unsafeAt)
and replacing ! with `unsafeAt` should give a speed-up, though probably not
terribly much. If you don't need the polymorphism and your array elements
are unboxable, using
On 17/03/10 21:30, Daniel Fischer wrote:
Am Mittwoch 17 März 2010 19:49:57 schrieb Artyom Kazak:
Hello!
I tried to implement the parallel Monte-Carlo method of computing Pi
number, using two cores:
move
But it uses only on core:
snip
We see that our one spark is pruned. Why?
Well, the
Am Donnerstag 18 März 2010 21:57:34 schrieb Daniel Fischer:
Contrary to my expectations, however, using unboxed arrays is slower
than straight arrays (in my tests).
However, a few {-# SPECIALISE #-} pragmas set the record straight.
Specialising speeds up both, boxed and unboxed arrays,
On 18 March 2010 21:34, Andrew Coppin andrewcop...@btinternet.com wrote:
Is there a tool anywhere which can figure out how to construct a function
with a specific type signature? Hoogle works if the thing you seek is a
single function, but not so much if you need to throw several functions
On 19/03/2010, at 08:48, Daniel Fischer wrote:
Am Donnerstag 18 März 2010 21:57:34 schrieb Daniel Fischer:
Contrary to my expectations, however, using unboxed arrays is slower
than straight arrays (in my tests).
However, a few {-# SPECIALISE #-} pragmas set the record straight.
This is
Hi, I think that Turbinado is no longer active since the author is
leaving Haskell (unless someone will adopt it)
http://www.alsonkemp.com/haskell/reflections-on-leaving-haskell/
-Keith
On Wed, Mar 17, 2010 at 5:25 PM, Hugo Gomes mr.hugo.go...@gmail.com wrote:
There is also turbinado. Im not
z_axis:
Erlang has yaws (http://yaws.hyber.org/)
Scala has lift (http://liftweb.net/)
Python has django (http://www.djangoproject.com/)
Ruby has rails (http://rubyonrails.org/)
How about haskell ? Is there any similar framework, which should be steady,
powerful and easy to use, in
Right now, the bottleneck of my program is in binarySearch', the function
must be called a few billion times.
Do you have any ideas on how to improve the performance of this function?
Bast solution for speeding up is to write it in assembler!
Ragards, Andrey
--
View this message in context:
Matthias Reisner schrieb:
Thanks, I missed that the flags are set dynamically if a dependency
cannot be satisfied.
Only cabal-install does this, plain Cabal only takes flags that were set
by the user.
___
Haskell-Cafe mailing list
Daniel Fischer wrote:
3.06GHz Pentium 4, 2 cores.
Do you have more info on that? Try:
grep 'model name' /proc/cpuinfo
The original Pentium 4 (eg Intel(R) Pentium(R) 4 CPU 3.00GHz) had
hyperthreading which was actually pretty pathetic for parallelism.
The Core 2 Duos (eg Intel(R)
Am Freitag 19 März 2010 00:56:15 schrieb Erik de Castro Lopo:
Daniel Fischer wrote:
3.06GHz Pentium 4, 2 cores.
Do you have more info on that? Try:
grep 'model name' /proc/cpuinfo
Well,
$ cat /proc/cpuinfo
processor : 0
On Fri, 19 Mar 2010 01:22:58 +0100, Daniel Fischer wrote:
core id : 0
cpu cores : 1
It is one of those pathetic single core pentium4 with so
called hyper-threading enabled. You should have checked the
intel product spreadsheet before investing such an old cpu.
--
Jc/*
%cat Test.hs
module Test(mcombs)
where
import Data.List
mcombs = foldr (flip (=) . f) [[]] where f x xs = [x:xs,xs]
%ghc -c -O2 Test.hs
%ghci
:l Test
Ok, modules loaded: Test.
:set +s
length $ mcombs [1..20]
1048576
(0.06 secs, 56099528 bytes)
length $ mcombs [1..50]
^CInterrupted.
Am Freitag 19 März 2010 02:25:47 schrieb Xiao-Yong Jin:
On Fri, 19 Mar 2010 01:22:58 +0100, Daniel Fischer wrote:
core id : 0
cpu cores : 1
It is one of those pathetic single core pentium4 with so
called hyper-threading enabled.
'kay, but why does it say
processor : 0
Am Freitag 19 März 2010 02:56:36 schrieb zaxis:
%cat Test.hs
module Test(mcombs)
where
import Data.List
mcombs = foldr (flip (=) . f) [[]] where f x xs = [x:xs,xs]
%ghc -c -O2 Test.hs
%ghci
:l Test
Ok, modules loaded: Test.
:set +s
length $ mcombs [1..20]
1048576
(0.06 secs,
Stephen Tetley wrote:
hi wren
Where I've used it, random access does seem conceptual more
satisfactory than trying to avoid it.
I was thinking more about performance issues (avoiding disk seeks) which
would also alleviate the problem of needing random access when it's not
available.
For
On Sun, Mar 14, 2010 at 9:03 AM, david fries d...@gmx.ch wrote:
Hello Café
Some time ago I wrote a parser for a project of one our customers. The
format was proprietary and binary. The data was structured as a tree
with tables pointing to sub tables farther in the file. (Well actually
there
Alternatively:
let f :: some type involving a
f = ...
f' :: a - some type involving a
f' _ = f
in f' (undefined :: Int) normal f arguments
On Thu, Mar 18, 2010 at 12:10 PM, Max Bolingbroke
batterseapo...@hotmail.com wrote:
Hi Paul,
You should be able to introduce \Lambda at the
On Mar 18, 2010, at 9:13 PM, Paul Brauner wrote:
Hi,
I was looking at hoogle documentation when I remembered that there is
some nice, but quite unusable, feature of squeak (smalltalk) which
allows you to search function in the library by giving a list of pairs
of inputs/ouputs.
The
On Thu, Mar 18, 2010 at 09:13:40AM +0100, Paul Brauner wrote:
Hi,
I was looking at hoogle documentation when I remembered that there is
some nice, but quite unusable, feature of squeak (smalltalk) which
allows you to search function in the library by giving a list of pairs
of inputs/ouputs.
Daniel Fischer wrote:
Am Freitag 19 März 2010 02:25:47 schrieb Xiao-Yong Jin:
It is one of those pathetic single core pentium4 with so
called hyper-threading enabled.
'kay, but why does it say
processor : 0
...
processor : 1
Hyperthreading is explained here:
let f x xs = [x:xs,xs]
:t f
f :: a - [a] - [[a]]
:t (=) .f
(=) .f :: a - ([[a]] - [a] - b) - [a] - b
:t (flip (=) .f)
(flip (=) .f) :: a - [[a]] - [[a]]
Why is the type of `(=) .f` and `flip (=) .f` so different ?
Sincerely!
-
fac n = let { f = foldr (*) 1 [1..n] } in f
--
View
Am Freitag 19 März 2010 04:24:21 schrieb Erik de Castro Lopo:
Daniel Fischer wrote:
Am Freitag 19 März 2010 02:25:47 schrieb Xiao-Yong Jin:
It is one of those pathetic single core pentium4 with so
called hyper-threading enabled.
'kay, but why does it say
processor : 0
...
Hint: look at the type of flip...
Also, there's a haskell-beginners mailing list. You may wish to post
there rather than asking us every question you get whilst learning
Haskell.
On 19 March 2010 14:34, zaxis z_a...@163.com wrote:
let f x xs = [x:xs,xs]
:t f
f :: a - [a] - [[a]]
:t (=) .f
On Thu, 2010-03-18 at 20:34 -0700, zaxis wrote:
let f x xs = [x:xs,xs]
:t f
f :: a - [a] - [[a]]
:t (=) .f
(=) .f :: a - ([[a]] - [a] - b) - [a] - b
Hmm. You seems to have defined Monad ((-) a).
(=) . f == \x - (=) (f x) == \x - (f x =)
1. x :: ∀ a. a from type of f
2. f :: ∀ a. a -
Yay! This was a week of hard work. I hope that somebody finds it valuable.
This package is a native implementation of the FastCGI protocol,
allowing Haskell to work with any webserver that supports it. It makes
no attempt to imitate the interface of the cgi-3000 and fastcgi-3000
packages,
Am Freitag 19 März 2010 04:34:53 schrieb zaxis:
let f x xs = [x:xs,xs]
:t f
f :: a - [a] - [[a]]
:t (=) .f
(=) .f :: a - ([[a]] - [a] - b) - [a] - b
:t (flip (=) .f)
(flip (=) .f) :: a - [[a]] - [[a]]
Why is the type of `(=) .f` and `flip (=) .f` so different ?
Because the
Sorry to bother again. I just cannot figure out how it could compile.
I got compile errors.
Can someone point out what is right code to use a do notion to make a
Parser works.
Thanks in advance.
newtype
Only one small nit here:
On Mar 18, 2010, at 09:58 , Tillmann Rendel wrote:
And we express Point as a GADT using Spherical and Cartesian as
follows.
data Point i
= Cartesian :: Cartesian_coord - Cartesian_coord - Point
Cartesian
| Spherical :: Latitude - Longitude - Point Spherical
On Mar 18, 2010, at 15:14 , Roderick Ford wrote:
... so, it looks like I am handling the IO wrong, or else I go
directly to the exitWith instead of returning the IO from return.
So, I suppose this is normal behavior, but how do you do BOTH. I
guess I should actually be printing the output
This looks very interesting, I look forward to checking it out. Implementing
FastCGI has always seemed too daunting a task to undertake; I salute you.
Are you familiar with the wai package? If so, do you believe your package is
amenable to either itself adapting the wai, or having a wrapper built
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