Hi all,
On 09/08/2021 16:31, Brandon Allbery wrote:
We haven't figured out what they did, but the other day we had someone
in #haskell with an infinite loop evaluating a dictionary. So
apparently it is possible for a dictionary to be bottom somehow.
I managed to do something like this once:
Hi all,
I have these functions:
toDouble :: (Rounding r, Precision p) => Rounded r p -> Double
fromDouble :: (Rounding r, Precision p) => Double -> Rounded r p
and I want to use RULES for optimization:
{-# RULES "realToFrac/toDouble" realToFrac = toDouble #-}
{-# RULES
Hi Alexander,
On 07/11/13 09:40, Alexander Herz wrote:
Hi,
I'm new to haskell and I tried to reproduce the perfomance values from
the paper Regular, Shape-polymorphic, Parallel Arrays in Haskell.
I modified the repa-mmult example from the repa-example package to use
the mmultP from
Hi Arie,
On 10/10/13 14:02, Arie Peterson wrote:
(Sorry for the long email.)
Summary: why does the attached program have non-constant memory use?
Looking at the heap profile graph (generated with +RTS -h, no need to
compile with profiling) I see the increasing memory use is split about
Hi Brian,
On 12/08/13 03:52, bri...@aracnet.com wrote:
...
Couldn't match expected type
...
Gtk.on Gtk.exposeEvent glCanvas $ \ _ - putStrLn foo
...
I looked up the type of Gtk.on and exposeEvent :
...
on
:: object
- Signal object callback - callback - IO (ConnectId object)
Hi Michael,
On 09/08/13 08:21, Michael Oswald wrote:
Hello,
I am currently writing an application which draws the structure of some
packets with help of the diagrams library directly to a GTK GUI.
Now the packets can have several hundreds of parameters which have to be
drawn so it takes
Hi Brian,
On 25/07/13 04:14, bri...@aracnet.com wrote:
This should be simple, and I thought it had it working, but I've broken it
and can't figure out why.
What I want is to invoke the callback whenever the user activates and entry
in a dialogbox, so I did both this :
Not sure what you
Hi Janek,
On 18/10/12 10:23, Janek S. wrote:
during past few days I spent a lot of time trying to figure out how to write
Criterion benchmarks,
so that results don't get skewed by lazy evaluation. I want to benchmark
different versions of an
algorithm doing numerical computations on a vector.
On 08/10/12 01:31, Michael Orlitzky wrote:
http://hackage.haskell.org/package/variable-precision
Mine may be unacceptably slow due to the dependent libraries.
I gave it a try -- the speed isn't an issue for me, but I need the trig
functions (which look like they pass through Double). These are
On 07/10/12 19:00, Michael Orlitzky wrote:
I'm trying to use,
http://hackage.haskell.org/package/numbers-3000.0.0.0
You might also try my:
http://hackage.haskell.org/package/variable-precision
It's Ord should work, I've used it in anger, otherwise let me know and
I'll fix it when I have
On 28/09/12 19:58, Patrick Mylund Nielsen wrote:
Check out the parallel combinators in parallel-io:
http://hackage.haskell.org/packages/archive/parallel-io/0.3.2/doc/html/Control-Concurrent-ParallelIO-Global.html
also
Hi Andres, list,
On 19/09/12 09:41, Andres Löh wrote:
Oops, I hit send too prematurely, sorry for the seeming bluntness (but it is
still a blunt message, can't apologize for that I suppose):
No need to apologize. There's a need for informal meetings as much (or
even more) as there is for
On 19/09/12 08:52, Andres Löh wrote:
Registration for all these events is open. I hope to see many
of you there.
Is there an informal hangout without the £225 price-tag
Cheers,
Andres
___
Haskell-Cafe mailing list
Haskell-Cafe@haskell.org
Hi list,
Oops, I hit send too prematurely, sorry for the seeming bluntness (but
it is still a blunt message, can't apologize for that I suppose):
On 19/09/12 09:14, Claude Heiland-Allen wrote:
On 19/09/12 08:52, Andres Löh wrote:
Registration for all these events is open. I hope to see many
Hi!
On 19/09/12 19:00, sdiy...@sjtu.edu.cn wrote:
So how do I force IO actions whose results are discarded (including IO ()) to
be strict?
() - foo :: IO () -- should work as it pattern matches, can wrap it in
a prettier combinator
!_ - foo :: IO a -- could work with -XBangPatterns
I've not
-BEGIN PGP SIGNED MESSAGE-
Hash: SHA1
Hi,
On 11/07/12 05:51, Magicloud Magiclouds wrote:
I cleaned out everything, no luck
On Fri, Jul 6, 2012 at 2:14 AM, Albert Y. C. Lai tre...@vex.net
wrote:
On 12-07-03 04:19 AM, Magicloud Magiclouds wrote:
-BEGIN PGP SIGNED MESSAGE-
Hash: SHA1
Hi all,
I wanted to try visual-prof[1] but found it was broken
by ghc RTS changes[2]. I ended up writing prof2pretty[3]:
http://hackage.haskell.org/package/prof2pretty
- --8--
sccpragmabomb adds SCC pragmas encoding source location.
prof2pretty
Hi Clark,
ghci is defaulting to Integer
modexp2 forces Int
Int overflows with 3^40
On 31/05/12 17:35, Clark Gaebel wrote:
*X 3^40 `mod` 3 == modexp2 3 40 3
False
*X fromInteger (3^40 `mod` 3) == modexp2 3 40 3
True
*X modexp2 3 40 3
0
*X 3^40 `mod` 3
0
*X 3^40 `mod` 3 ::Int
2
I'm
Hi there,
On 25/05/12 08:07, . wrote:
On Fri, 2012-05-25 at 08:24 +0800, Conrad Parker wrote:
I've downloaded and built this. I had to also download Claude
Heiland-Allen's v4l2 source from gitorious, as that package does not
seem to be on hackage (though his other related packages are). I
Hi all,
I'm pleased to announce variable-precision-0.2:
http://hackage.haskell.org/package/variable-precision
There was no announcement for previous versions, as I quickly found
their flaws to be too irritating in practice.
--8-- excerpt from the hackage page
Software floating point with
Hi all,
I'm pleased to announce bitwise-0.1:
http://hackage.haskell.org/package/bitwise
--8-- excerpt from the hackage page
Unboxed multidimensional bit packed Bool arrays with fast aggregate
operations based on lifting Bool operations to bitwise operations.
There are many other bit packed
Hi all,
What's the recommended way to get hint[0] to play nice with type
synonyms[1]?
A problem occurs with in scope type synonyms involving types not in scope.
I came up with this after looking at the source[2], but it makes me feel
ill:
--8--
-- hint and type synonyms don't play nice
,
Claude
Thanks,
Daniel
On Mar 31, 2012, at 6:19 PM, Claude Heiland-Allen wrote:
Hi all,
What's the recommended way to get hint[0] to play nice with type synonyms[1]?
A problem occurs with in scope type synonyms involving types not in scope.
I came up with this after looking at the source[2
On 14/03/12 14:01, rajendra prasad wrote:
My c++ code(HelloWorld.cpp) looks like this:
Try adding extern C { ... } to use the C ABI instead of a C++ ABI
(which usually features symbol name mangling to add type information,
among other things). (This may not solve the entire problem, but is
Hi,
On 30/01/12 01:07, Joey Hess wrote:
The attached test case quickly chews up hundreds of MB of memory.
If modified to call work' instead, it runs in constant space.
Somehow the value repeatedly read in from the file and stored in
the state is leaking. Can anyone help me understand why?
On 14/12/11 13:59, Marc Weber wrote:
Excerpts from Michael Snoyman's message of Wed Dec 14 14:34:30 +0100 2011:
On Wed, Dec 14, 2011 at 3:31 PM, C K Kashyapckkash...@gmail.com wrote:
Definite *don't* use read/show: if you make any updates to your data
structures, all old files will be lost.
On 02/11/11 09:17, Eugene Kirpichov wrote:
Hello,
I've got two very simple programs that draw a very simple picture using
cairo, doing a couple hundred thousand of cairo calls.
One program is in C++. The other is in Haskell and uses the cairo library
bindings.
The C++ program completes in a
On 30/09/11 02:45, DukeDave wrote:
1. Is there some reason (other than 'safety') that cabal install cleans
everything up?
As far as I've experienced and understand it, it doesn't - it's more
that GHC can detect when Haskell modules don't need recompiling while
the same is not true for C or
Hi,
On 05/07/11 10:19, Christopher Done wrote:
[snip]
/usr/bin/ld:
/home/chris/.cabal/lib/bindings-posix-1.2.2/ghc-6.12.3/libHSbindings-posix-1.2.2.a(Signal.o):(.text+0x5dfb):
error: undefined reference to 'pthread_kill'
[snip]
I guess on Claude's system it's linked to by default. So for
Greetings all,
I uploaded 4 new packages that may be of interest:
bindings-linux-videodev2 0.1
- bindings to Video For Linux Two (v4l2) kernel interfaces
http://hackage.haskell.org/package/bindings-linux-videodev2-0.1
bindings-mmap 0.1
- bindings to mmap for POSIX
Hi,
On 15/06/11 12:13, kaffeepause73 wrote:
let m = read text :: [[Double]]
signalImport: Prelude.read: no parse
read :: String - [[Double]] -- expects Haskell syntax
try something like:
parse :: String - [[Double]] -- expects plainer syntax
parse = map (map read . words) . lines
Hi,
On 07/06/11 14:22, Johannes Waldmann wrote:
Would this work better with Data.Sequence instead of List?
(Is there a really cheap way (O(1)) to split some Data.Sequence roughly in
half?)
I came up with this using immutable unboxed arrays, which gives a nice
parallel speedup (and somehow
On 15/02/11 20:35, Daniel Fischer wrote:
Which makes me wonder: unwanted sharing of lists [1 .. n] or similar is a
frequent cause of space leaks, so would it be possible to teach GHC to not
share such lists (unless they're bound to a name to indicate sharing is
wanted)?
In particular for
Hi Phil,
On 22/01/11 23:13, gutti wrote:
- are t a b c d points or curve parameters ?
a b c d are points, t is the interpolation coefficient (between 0 and 1)
- how does lifting to matrix create a 1d spline to a 2d spline ? -- I don't
see how it works
essentially, it creates a matrix of
Hi Phil,
On 22/01/11 14:07, gutti wrote:
Dear Haskellers,
I'm looking for Vector and especially Matric interpolation ala:
z = interp2 (xMatrix, yMatrix, zMatrix, x, y)
- x and y can be single values or also vectors or matrices
- indeally with the options nearest, linear,
Hi everyone,
I've been working on [0] Haskell bindings for [1] libqd for [2]
double-double and quad-double arithmetic, and have been struggling to
implement [3] RealFloat, in particular [4] decodeFloat, mostly because
of its postcondition but also some issues relating to variable precision:
On 23/10/10 23:17, Donn Cave wrote:
Quoth Claude Heiland-Allenclaudiusmaxi...@goto10.org,
...
The conclusion I drew was that unsafe foreign functions block the
current capability (OS thread) and any threads (Haskell forkIO etc)
currently scheduled on that capability, but other capabilities and
Hi Aditya,
The problem is not that the file was not loaded, but that in Lua,
loading a file only loads it and does not execute it; Lua is a dynamic
language, by which I mean that definitions are created through execution.
Attached is a simple example, note that there is no proper error
On 23/10/10 17:42, Gregory Crosswhite wrote:
On 10/23/10 7:54 AM, John Lato wrote:
On Fri, Oct 22, 2010 at 6:16 PM, Bulat Ziganshin
bulat.zigans...@gmail.com mailto:bulat.zigans...@gmail.com wrote:
Hello John,
Monday, October 18, 2010, 8:15:42 PM, you wrote:
If anyone is listening, I would
On 23/10/10 23:28, Manlio Perillo wrote:
Hi.
What are the available methods to execute IO actions from pure code?
I know only unsafePerformIO and foreign import (to call a non pure
foreign function).
Assuming I want to execute external untrusted code using plugins (via
the `plugins`
On 02/08/10 15:14, Tom Davies wrote:
I find it convenient sometimes to convert a Maybe value to an Either thus
(excuse the syntax, it's CAL, not Haskell):
maybeToEither :: a - Maybe b - Either a b;
maybeToEither errorValue = maybe (Left errorValue) (\x - Right x);
but that seemingly
Greeting,
Jitter vs Throughput
Scenario
I have the following scenario:
CPU with [C] cores
concurrent program
the 1 main thread uses OpenGL for animated visual output
[W] worker threads uses FFI to lengthy numerical computations
with the following desires :
On 31/07/10 12:13, wren ng thornton wrote:
Stephen Tetley wrote:
wren ng thornton wrote:
Ben wrote:
unzipMap :: M.Map a (b, c) - (M.Map a b, M.Map a c)
unzipMap m = (M.map fst m, M.map snd m)
I don't think you can give a more efficient implementation using the
public
interface of Data.Map.
On 31/07/10 13:49, Stephen Tetley wrote:
Although I haven't calculated the Big-O scores suspect that original
post will actually be the best, the solutions that metamorph into a
list and out again look like they're doing needless extra work.
They're both O(size m) time, and yes the original is
Hi,
On 16/07/10 07:35, C K Kashyap wrote:
Haskell without using any standard library stuff?
For example, if I wanted an image representation such as this
[[(Int,Int.Int)]] - basically a list of lists of 3 tuples (rgb) and
wanted to do in place replacement to set the pixel values, how could I
Gregory Propf wrote:
Say I have something like
data DT a = Foo a | Bar a | Boo a
I want something like a list of the constructors of DT, perhaps as [TypeRep].
I'm using Data.Typeable but can't seem to find what I need in there.
Everything there operates over constructors, not types.
The
pat browne wrote:
Hi,
Does anyone know where there are any Haskell implementations of the the
River Crossing puzzle (AKA Farmer/Fox/Goose/Grain).
I wrote some code to generate a map of some version of the game:
https://code.goto10.org/svn/maximus/2009/boatman/BoatMan.hs
ghc -O2 --make
Andrew Coppin wrote:
(OK, well the *best* way is to use the GPU. But AFAIK that's still a
theoretical research project, so we'll leave that for now.)
Works for me :-)
http://claudiusmaximus.goto10.org/cm/2009-09-24_fl4m6e_in_haskell.html
There doesn't need to be a sound theoretical
Greetings,
I have an idea for a project. The eventual aim is rather eccentric, but
the specifications I have sketched out are roughly as follows (best
viewed with fixed-width font due to diagrams):
0. the graphical user interface is entirely mouse driven, mouse
position/clicks/releases
Casey Hawthorne wrote:
When folding is there a way to pick out the last point being
processed?
I came up with these:
safeHead = foldr (const . Just) Nothing
safeLast = foldr (flip mplus . Just) Nothing
Claude
--
http://claudiusmaximus.goto10.org
Hi Vasili,
Vasili I. Galchin wrote:
[snip]
import System.Process
main = do
handle - runProcess
blastall -- executable
[-p blastn] -- CLI args
Try:
[-p, blastn]
This passes multiple command line arguments instead of just one that
contains a space.
Maurício wrote:
Hi,
Why is this wrong?
class MyClass r where function :: r - s
data MyData u = MyData u
instance MyClass (MyData v) where function (MyData a) = a
GHC says that the type of the result of 'function' is both determined by
the rigid type from MyClass and the rigid
Maurício wrote:
Hi,
How is CStringLen supposed to be used? The only
usual C string I'm familiar with is the null
terminated sequence of chars. I remember some
Pascal version where the first 2 bytes were used
as an integer counting the following characters.
What is the convention used in
Jefferson Heard wrote:
Adrian, my understanding is that it's not that simple, because I need
to preserve the state between calls to GLUT's callbacks, which all
return IO ().
Then maybe see:
http://www.haskell.org/pipermail/haskell-cafe/2007-July/028501.html
2008/8/6 Adrian Neumann [EMAIL
naruto canada wrote:
I run into linking error with parsec:
ghc -o /tmp/a.out accu.hs
Try ghc --make, or pass appropriate package flags on the command line so
that it gets linked with Parsec.
Claude
--
http://claudiusmaximus.goto10.org
___
Galchin, Vasili wrote:
Hello,
I want to model a Haskell function that is a callback from C. I have
only found one example in the unix package's Semaphore.hsc, which apparently
is not used. I want to be able to marshall a Haskell function that is a
first class citizen residing in a
Madoc wrote:
Given a list of numbers, I want to modify each of those numbers by adding a
random offset. However, each such modified number shall stay within certain
bounds, given by the integers minValue and maxValue. After that, I want to
continue computation with the resulting list of type
Thomas Girod wrote:
Hi there. Following this advice
(http://reddit.com/info/6hknz/comments/c03vdc7), I'm posting here.
Recently, I read a few articles about Haskell (and FP in general) and
music/sound.
I remember an article ranting about how lazy evaluation would be great
to do signal
Galchin, Vasili wrote:
data Bozo =
Bozo {
id :: Int
}
bonzo :: Maybe Bozo - IO ()
bonzo maybe_bozo = do
if maybe_bozo == (Just (Bozo x))
then
return ()
else
return ()
~
I want x to be a pattern that matches id ??
Try:
bonzo (Just
Paul Johnson wrote:
I'm using arrows for the first time, with HXT. I think I'm getting the
hang of it, but one problem has me stumped. I have a function
lookupFormatter which takes a string and returns an arrow, and I want
to use that arrow. Something like this:
myProblem :: (ArrowXml a)
Jinwoo Lee wrote:
Hi,
Recently I wrote a code that uses readline library
(System.Console.Readline).
I had to maintain a state (file path) and do IO throughout the code, so
I decided to use StateT monad.
The problem was that in order to retrieve the current state (file path)
inside the
Jason Dusek wrote:
Stefan O'Rear [EMAIL PROTECTED] wrote:
The only type that you are allowed to assume corresponds to a C int is
CInt, in the Foreign.C.Types module. This probably isn't the problem,
but it could make problems of its own on a 64-bit or otherwise weird
system.
So say I
Hans Aberg wrote:
When experimenting with list index sets (i.e. lists more general than
provided by Haskell), I arrived at the problem that in the example code
below for example
h(list 6)
does not (in Hugs) write out the beginning of the list lazily. It does
work for
list 6
first (list
Thomas Engel wrote:
inputvalues :: IO Input -- add a return (ve,de,...) to the end
compute :: Input - Output
How can I combine several function (calculations) in this function?
compute1 :: Input - Output1
compute2 :: Input - Output2
combine :: Output1 - Output2 - Output
compute input =
Galchin Vasili wrote:
line #102 ...
allocaBytes (#const sizeof(struct mq_attr)) $ \ p_attrs - do
definition of struct mq_attr on Linux ...
struct mq_attr
{
long int mq_flags;/* Message queue flags. */
long int mq_maxmsg; /* Maximum number of messages. */
long int
Bruce, Joseph R (Joe) wrote:
[snip]
I hadn't looked at CABAL before. It's a very useful tool and met all my
library-forming needs.
That's only half my problem though. I'm trying to make the use of this Haskell
code as transparent as possible to the C programmers on the team. Telling them
ChrisK wrote:
Could I has one question? What is the purpose of the stream function
in the ArrowLoop instance? Is it just to catch an unexpected [] at
runtime?
instance ArrowLoop SF where
loop (SF f) = SF $ \as -
let (bs,cs) = unzip (f (zip as (stream cs))) in bs
where stream
david48 wrote:
| I'm really inexperienced at this :
class Gadget g where
fInit :: g - a - g
data FString = FString !Int !String deriving Show
instance Gadget FString where
fInit (FString n _) s = FString n (take n s)
The types of:
fInit :: g - a - g
and:
take :: Int - [a] - [a]
Denis Bueno wrote:
On Dec 7, 2007 1:50 PM, Andrew Coppin [EMAIL PROTECTED] wrote:
Hi guys.
Here's a fairly basic question. I have several ideas for programs that
I'd like to write. They all involve placing units of some kind, and
then drawing connections between those units. How feasible is it
Paulo J. Matos wrote:
Hi all,
I'm curious about the best way to typeset haskell code in a wordpress
blog. Using blockquote removes all indentation. :-(
Cheers,
Probably HsColour:
http://www.cs.york.ac.uk/fp/darcs/hscolour/
--8--
hscolour is a small Haskell script to colourise Haskell code.
Evan Laforge wrote:
The only thing I'm uncertain about is whether it would have good
enough time and space performance. All the real work is writing yet
another set of basic envelope, oscillator, and fft primitives. You
*should* be able to go all the way down to the samples in pure haskell
Hi Dave, everyone...
Dave Tapley wrote:
Hi all,
I'm having a lot of trouble using renderString from Graphics.UI.GLUT.Fonts.
All my attempts to render a StrokeFont have so far failed.
Using a BitmapFont I can get strings to appear but they demonstrate
the odd behaviour of translating themselves
Hi people,
I'm embedding Haskell into a C program with a stateful objects with
message passing paradigm [0]. I want to make boxes with useful
functions, then connect them together within the C program. I know how
to build a working version using Data.Dynamic, but that loses
polymorphism
Hi,
I think the FFI Addendum should make explicit that FunPtr values are
stable (in the sense of StablePtr).
I'm writing a Haskell plugin for an application written in C, and the
control flow is:
C-Haskell-C ; C-Haskell-C ; ...
and I was confused by this statement in section 4.1 of
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