I had this conversation recently. My experience with implementing RK4 in
RSAGL led me to some contrary conclusions:
First, ODEs aren't necessarily useful for interpreting externally sampled
events, because you don't have the ability to run, i.e. RK4 against a
mouse cursor position without
There seems to be an assumption amongst the community that a user's
home directory is the most useful place for cabal to install to by
default. A few people have challenged that. I wanted to find out
which one most people do actually prefer, so please go and vote on
this poll.
On Mon, Apr 20, 2009 at 10:21 PM, Richard O'Keefe o...@cs.otago.ac.nz wrote:
On 21 Apr 2009, at 5:10 pm, Jason Dagit wrote:
Plus, there was a movement to ban them:
And somehow this means people don't?
...see the humor.
BUT, here is the real point of my reply:
To end this debate as to
Richard O'Keefe wrote:
On 21 Apr 2009, at 2:10 pm, Edward Middleton wrote:
Using non-standard installation methods makes it harder for package
maintainers to package the application and suggests you haven't taken
any care / don't care about making global installation safe.
I'm sorry, there
I'm sorry, there is no such animal as safe global installation,
in the sense of download this one package and do what it says.
Well I have been doing that for more then 10 years, it is one of the
functions any decent package management systems is designed to do.
Time to adopt another goodie
Paul,
Thank you for your reply.
Integration is a tool to solve a some ODEs but ot all of them. Suppose all
we have is a paper and a pencil and we need to symbolically solve:
/ t
de(t)/dt = f(t) - the solution is given by
For what it's worth, It's bothered me often enough that cabal doesn't
install globally by default that I had to reinstall ghc in order to solve
package issues.
So I'd prefer the default to be global.
But I don't care that much, I don't think arguing that point is leading
anywhere.
Thomas Davie tom.da...@gmail.com wrote:
There seems to be an assumption amongst the community that a user's
home directory is the most useful place for cabal to install to by
default. A few people have challenged that. I wanted to find out
which one most people do actually prefer, so
Richard O'Keefe o...@cs.otago.ac.nz wrote:
This is good advice (/usr/local is fine though).
Actually, no, it isn't.
To start with, these days it's chock full of stuff
which is hardly less critical for system operation
than anything you'll find in /bin.
More importantly, /usr/local is a
Hello.
I want to build regex-tdfa-1.1.1 haddock documentation locally, but the
procedure fails:
$ ./setup haddock
Preprocessing library regex-tdfa-1.1.1...
Running Haddock for regex-tdfa-1.1.1...
Warning: The documentation for the following packages are not installed. No
links will be generated
Edward Middleton emiddle...@bebear.net wrote:
ghc 6.8.3 is /usr/bin/ghc on my office Mac, but nothing in the world
prevents there being some other program called ghc that would also
like to be there. Only by painstaking verification of a whole
bunch of applications together can one be
Adam-Bashford method can be easily implemented to replace Euler's. But
to really get higher accuracy, one may need variable time steps and
perhaps even back tracking, which is an interesting topic on its own.
But my question is, is FRP really the right setting in which to
explore a highly accurate
Well, the current FRP systems don't accurately solve this, since they just
use an Euler integrator, as do many games. As long as the time steps are
tiny enough this usually works good enough. But I wouldn't use these FRPs to
guide an expensive robot or spaceship at high precision :-)
On Tue, Apr
Hello.
How mkRegex and matchRegex can be used with the regex-tdfa backend in
ghci?
The following fails:
$ ghci
GHCi, version 6.10.2: http://www.haskell.org/ghc/ :? for help
Loading package ghc-prim ... linking ... done.
Loading package integer ... linking ... done.
Loading package base ...
Achim Schneider wrote:
Edward Middleton emiddle...@bebear.net wrote:
ghc 6.8.3 is /usr/bin/ghc on my office Mac, but nothing in the world
prevents there being some other program called ghc that would also
like to be there. Only by painstaking verification of a whole
bunch of
Hey thanks for the Adam-Bashford tip, didn't know that one yet (although I
used similar techniques in the past, didn't know it had a name :-)
Well, solving the ODE is usually the task of a dedicated physics engine. But
IMHO with FRP we try to reuse small building blocks so we get very modular
BTW, a bit of topic, your recent work on causal commutative arrows and CCA
compiler seems very promising. Any news on that? Seems that it could
drastically speedup Yampa.
On Tue, Apr 21, 2009 at 1:32 PM, Peter Verswyvelen bugf...@gmail.comwrote:
Hey thanks for the Adam-Bashford tip, didn't know
Richard O'Keefe o...@cs.otago.ac.nz wrote:
Some of the right questions are
- how many potential whatever users would need to have
whatever installed on _some_ machine they do NOT have
administrator access to?
Irrelevant.
- if people find Mac and Windows installers that show you
Edward Middleton emiddle...@bebear.net wrote:
Achim Schneider wrote:
Edward Middleton emiddle...@bebear.net wrote:
ghc 6.8.3 is /usr/bin/ghc on my office Mac, but nothing in the
world prevents there being some other program called ghc that
would also like to be there. Only by
Achim Schneider bars...@web.de writes:
Richard O'Keefe o...@cs.otago.ac.nz wrote:
This is good advice (/usr/local is fine though).
Actually, no, it isn't.
To start with, these days it's chock full of stuff
which is hardly less critical for system operation
than anything you'll find in
Am Donnerstag, 16. April 2009 10:06 schrieb Patai Gergely:
unsafePerformIO is apparently never inlined, i.e. each instance is
executed once, so sharing works as desired
But expressions that use unsafePerformIO might get inlined.
CSE is no problem either, it even helps if it's performed (and
$ cat .cabal/config
...
root-cmd: sudo
...
user-install: False
...
On 21 Apr 2009, at 14:41, Achim Schneider wrote:
Thomas Davie tom.da...@gmail.com wrote:
There seems to be an assumption amongst the community that a user's
home directory is the most useful place for cabal to install to by
Achim Schneider bars...@web.de writes:
Thomas Davie tom.da...@gmail.com wrote:
There seems to be an assumption amongst the community that a user's
home directory is the most useful place for cabal to install to by
default. A few people have challenged that. I wanted to find out
Dear all,
reading that
according the several style guides, lines shouldn't be too long
(longer than 78 characters).
http://www.cs.caltech.edu/courses/cs11/material/haskell/misc/haskell_style_guide.html
http://www.haskell.org/haskellwiki/Programming_guidelines
I would like to know, whether
Dusan Kolar ko...@fit.vutbr.cz wrote:
Dear all,
reading that
according the several style guides, lines shouldn't be too long
(longer than 78 characters).
http://www.cs.caltech.edu/courses/cs11/material/haskell/misc/haskell_style_guide.html
Dusan Kolar ko...@fit.vutbr.cz writes:
Dear all,
reading that
according the several style guides, lines shouldn't be too long
(longer than 78 characters).
http://www.cs.caltech.edu/courses/cs11/material/haskell/misc/haskell_style_guide.html
Hi
I believe it is a good practice too keep each line short and
easy to read. The following is taken from python style
guide.
Maximum Line Length
Limit all lines to a maximum of 79 characters.
There are still many devices around that are limited to 80 character
lines; plus,
I've finally found the time to take another look at your haskell mode
for vim. Two questions so far:
1. I think earlier my indentation mode would match indentation of the
previous line by default, after installing your scripts I always end
up in column 1 after pressing return. Is there some
Dusan Kolar wrote:
I would like to know, whether 78 characters bound still makes a sense...
Yes, but I wouldn't fight for a single character.
Even if I connect to my linux box with text terminal, it is not a 80x24
characters HW text terminal, but a window emulating this in whatever
else OS,
Maybe it has gone unnoticed, but the main reason we made the compiler
available, was to make it possible for others to experiment with its
type extensions, its Grin based back-end and to show the advantages
(and disadvantages?) of generating large part of the compiler from an
attribute
Peter, Paul,
But my question is, is FRP really the right setting in which to
explore a highly accurate ODE solver?
Well, solving the ODE is usually the task of a dedicated physics engine.
But IMHO with FRP we try to reuse small building blocks so we get very
modular systems; a big physics black
Luke Palmer ha scritto:
[...]
Note that it is not always possible to separate IO from pure code.
As an example, consider an HTTP 1.1 server that read a request body
containing a number for each line, and return a response body containing
the sum of the numbers.
What?
|I've finally found the time to take another look at your haskell mode
|for vim. Two questions so far:
|1. I think earlier my indentation mode would match indentation of the
|previous line by default, after installing your scripts I always end
|up in column 1 after pressing return. Is there
Hello S.,
Tuesday, April 21, 2009, 5:42:15 PM, you wrote:
If we had been interested in raising fierce discussions about n+k
patterns or how and where cabal installs things, we could have easily
achieved the same effect with much less effort.
you mean that we should shoot up? :)
--
Best
If we had been interested in raising fierce discussions about n+k
patterns or how and where cabal installs things, we could have easily
achieved the same effect with much less effort.
you mean that we should shoot up? :)
If the release of UHC contributes to whatever discussion regarding
The longer a line the more difficult it is to move the focus to the
beginning of the next line when reading.
Hmm, then I must be doing something wrong, I do not fully fill program
lines... ;-)
Or my comments are too short. I do not think, this is an issue, to catch
the next line, if the
I think the only way your release is going to get significant feedback
is when it's ready to compile substantial existing Haskell programs
unaltered.
I might try UHC on some toy example for a few minuts, but if it falls
over when I give it code that I've already written I'll soon give up
using it.
That sounds fine... I think I'll pick Numeric. RungeKutta. I'll
change it when I've cabalized hackage-ized this puppy...
Uwe
On 4/20/09, Alexander Dunlap alexander.dun...@gmail.com wrote:
It would also be nice if you could plug it into the hierarchical
module system somewhere, perhaps
Dusan Kolar wrote:
...
Or is the reason much deeper? Or, is the bound set to 78 characters just
because it is as good number as any other?
...
As a little historical detour I think the 80 character limit goes back
to 1928 when IBM designed their punched card format
I've been using the latest and greatest version of leksah for the last
couple of weeks and I wanted to give a short report on the things I've
found.
First of all, it's crashed only once, and the error was an actual
segfault, so I'm not sure what went wrong there. All in all, I like
the eyecandy
On Tue, Apr 21, 2009 at 2:51 PM, Claus Reinke claus.rei...@talk21.com wrote:
|I've finally found the time to take another look at your haskell mode
|for vim. Two questions so far:
|1. I think earlier my indentation mode would match indentation of the
|previous line by default, after
I've seen it on the Hackaton and was really impressed.
Were you using it on Windows? I haven't tried it yet since I heard it has
major problems on Windows.
On Tue, Apr 21, 2009 at 5:06 PM, Jeff Heard jefferson.r.he...@gmail.comwrote:
I've been using the latest and greatest version of leksah for
I'm using it on Ubuntu Linux 8.10 and on Mac OS X 10.5.x
-- Jeff
On Tue, Apr 21, 2009 at 11:12 AM, Peter Verswyvelen bugf...@gmail.com wrote:
I've seen it on the Hackaton and was really impressed.
Were you using it on Windows? I haven't tried it yet since I heard it has
major problems on
But expressions that use unsafePerformIO might get inlined.
That's true, but given the way this interface is used, this doesn't seem
to be an issue, since there are typically no unsafePerformIO's hidden
deep inside an expression without a chain of Elerea primitives leading
to it.
What about
I find a hard 80 character line length limit to be somewhat ridiculous in
this day and age. I've long since revised my personal rule of thumb upwards
towards 132, if only because I can still show two windows of that side by
side with no worries, along with all the IDE browsing baggage, even on a
Edward Kmett ekm...@gmail.com writes:
I find a hard 80 character line length limit to be somewhat ridiculous in this
day and age. I've long since revised my personal rule of thumb upwards towards
132, if only because I can still show two windows of that side by side with no
worries, along
Xiao-Yong Jin xj2...@columbia.edu wrote:
Edward Kmett ekm...@gmail.com writes:
I find a hard 80 character line length limit to be
somewhat ridiculous in this
day and age. I've long since revised my personal
rule of thumb upwards towards
132, if only because I can still show two
|Yes, I found that one myself. My old ftplugin/haskell.vim used to
|have autoindent set, but importing your haskell mode overwrote that
|(slightly irritating behaviour if you ask me ;-). Putting my old
|config into ftplugin/haskell_mine.vim restored the behaviour.
Yes, one cannot have two
Robert Greayer robgrea...@yahoo.com writes:
Xiao-Yong Jin xj2...@columbia.edu wrote:
Edward Kmett ekm...@gmail.com writes:
I find a hard 80 character line length limit to be
somewhat ridiculous in this
day and age. I've long since revised my personal
rule of thumb upwards towards
Jeff Heard wrote:
First of all, it's crashed only once, and the error was an actual
segfault, so I'm not sure what went wrong there. All in all, I like
the eyecandy and have left it on for everything I do, but I've noticed
that arrows have an extra space after them, no matter which arrow.
Also,
Hi,
I have been trying to specify the depth-first numbering algorithm as follow:
_dfNum :: Int - [Tree a] - [Tree Int]
_dfNum i ((Node n ts):us) = (Node i vs):(_dfNum (i+1+(length ts)) us) where
vs=_dfNum (i+1) ts
But when I test it, I receive the message:
Non-exhaustive
Am Dienstag 21 April 2009 20:52:40 schrieb siso dagbovie:
Hi,
I have been trying to specify the depth-first numbering algorithm as follow:
_dfNum :: Int - [Tree a] - [Tree Int]
_dfNum i ((Node n ts):us) = (Node i vs):(_dfNum (i+1+(length ts)) us)
where vs=_dfNum (i+1) ts
But
Matti Niemenmaa wrote:
In order to run properly, list-tries needs a version of 'containers'
that hasn't yet been released. I incorporated a little hack which makes
it compile even with 0.2, but some calls will fail by calling 'error':
30 of my 1014 test cases do so.
1014 test cases?! Wow. :-)
Announcing the first public release of list-tries! Version 0.0, woo!
list-tries is a library providing implementations of finite sets and
maps for list keys using tries, both simple and of the Patricia kind.
The data types are parametrized over the map type they use internally to
store the child
Martijn van Steenbergen wrote:
Matti Niemenmaa wrote:
In order to run properly, list-tries needs a version of 'containers'
that hasn't yet been released. I incorporated a little hack which makes
it compile even with 0.2, but some calls will fail by calling 'error':
30 of my 1014 test cases do
On Wed, Apr 22, 2009 at 12:29:05AM +0300, Matti Niemenmaa wrote:
Good to hear that it works for someone else, too. (I don't have a new
enough version of containers installed myself, after upgrading to
6.10.2.) Just bear in mind that some functions won't work.
What exactly don't work? What is
Robert Greayer wrote:
But the discussion is about a coding standard -- surely if I claimed to like to
have 4 windows side by side, that wouldn't be a good reason to reduce the
standard
to 40 columns? Being able to read one line 'at a glance' seems to me to be
improved if that line contains
On Tue, 2009-04-21 at 09:20 +0200, Thomas Davie wrote:
There seems to be an assumption amongst the community that a user's
home directory is the most useful place for cabal to install to by
default. A few people have challenged that. I wanted to find out
which one most people do
On Sun, 19 Apr 2009, Manlio Perillo wrote:
Note that it is not always possible to separate IO from pure code.
As an example, consider an HTTP 1.1 server that read a request body
containing a number for each line, and return a response body containing
the sum of the numbers.
Here, you can not
Hello Jeff
Jeff Heard wrote:
I've been using the latest and greatest version of leksah for the last
couple of weeks and I wanted to give a short report on the things I've
found.
Thanks for taking the time to write this report.
Jeff Heard wrote:
First of all, it's crashed only once,
according the several style guides, lines shouldn't be too long
(longer than 78 characters).
Since Haskell is usually nice to parse, wouldn't it be
interesting to replace a pretty printer program for layout
manuals? I saw in your first link that the teacher provided
a tool to check for
Xiao-Yong Jin schrieb:
P.S. We really need such a well written style guide for
haskell. Python has this nice PEP (Python Enhancement
Proposals). Should we start making our own HEP?
http://www.haskell.org/haskellwiki/Category:Proposals
On Tue, 2009-04-21 at 12:41 +0200, Achim Schneider wrote:
alias cabal='cabal --global'
We do have a config file you know. It's exactly to let you persistently
set command line flags like this.
Duncan
___
Haskell-Cafe mailing list
On Tue, 2009-04-21 at 13:52 +0100, Neil Mitchell wrote:
P.S. We really need such a well written style guide for
haskell. Python has this nice PEP (Python Enhancement
Proposals). Should we start making our own HEP?
We have one: urchin.earth.li/~ian/style/haskell.html
Yes,
On Tue, 2009-04-21 at 12:31 +0200, david48 wrote:
For what it's worth, It's bothered me often enough that cabal doesn't
install globally by default that I had to reinstall ghc in order to
solve package issues.
Do you know what the problem was exactly? It's possible to get problems
with overlap
In category theory functors are defined between two category of C and D
where every object and morphism from C is mapped to D.
I am trying to make sense of the above definition with functor class in
Haskell. Let say I am dealing with List type. When I define List to be a
instance of a functor
You are on the right track. The usual construction is that Hask is the
category (with types as objects and functions as morphisms).
Functor F is then an endofunctor taking Hask to itself:
a - F a
f - fmap f
So, for F = []:
a - [a]
f - map f
Natural transformations are then any fully
Hi, i hate those html forms that show you [haskell,python] code in a narrow
box that is suposed to make the code clear, but it darkens the code by
cutting it.
Maybe having all lines shorter helps, but the narrow window effect is
chasing us nonsensely.-
haroldo
2009/4/21 Richard Kelsall
Daryoush Mehrtash dmehrt...@gmail.com wrote:
In category theory functors are defined between two category of C and
D where every object and morphism from C is mapped to D.
I am trying to make sense of the above definition with functor class
in Haskell. Let say I am dealing with List type.
I am not sure I follow how the endofunctor gave me the 2nd functor.
As I read the transformation there are two catagories C and D and two
functors F and G between the same two catagories. My problem is that I only
have one functor between the Hask and List catagories. So where does the
2nd
How do I get the x out of Just x?
Michael
=
safeDivision :: Float - Float - Maybe Float
safeDivision x y = if y == 0 then Nothing else Just (x/y)
*Main Data.List safeDivision 10 5
Just 2.0
*Main Data.List 3 + (safeDivision 10 5)
interactive:1:0:
No instance for (Num (Maybe
If you want to just get the value out, meaning you'll get a program
error if it happens to be Nothing, then you can use
Data.Maybe.fromJust. But usually, you'd want to preserve the Nothing.
Applicative or Monad is pretty good for this:
import Control.Applicative
(3+) $ safeDivision 10 5
You mean, the x out of *Maybe* x even. In the very literal sense, the
assumption that there is an x in Maybe x is false -- there may not be
one since it is maybe, but not necessarily, x. IT's a bit like the use
of null that you might have seen in other languages where you might have
a value or you
On Tue, 2009-04-21 at 17:49 -0700, michael rice wrote:
How do I get the x out of Just x?
Michael
=
safeDivision :: Float - Float - Maybe Float
safeDivision x y = if y == 0 then Nothing else Just (x/y)
*Main Data.List safeDivision 10 5
Just 2.0
*Main Data.List 3 +
Got it! I figured there must be some way to unpack it.
My goodness, there are so many functions I'm not even aware of. Has anyone ever
counted them all?
Thanks.
Michael
--- On Tue, 4/21/09, Tony Morris tonymor...@gmail.com wrote:
From: Tony Morris tonymor...@gmail.com
Subject: Re:
List is not a full subcategory of Hask, so it's a bad choice. Namely,
types of functions on a list (e.g. [a] - [a]) are not themselves lists
of type [b] for some b, and so are not objects of List (though they are
morphisms in it). In Hask, ([a] - [a]) is both an object and a morphism
(in fact,
There's a lot of well thought out stuff in Haskell, but getting familiar with
it all seems like a huge task.
Thanks for the help.
Michael
--- On Tue, 4/21/09, Ross Mellgren rmm-hask...@z.odi.ac wrote:
From: Ross Mellgren rmm-hask...@z.odi.ac
Subject: Re: [Haskell-cafe] Getting the x out
To:
Hi,
a refresh release of the HTTP package has been uploaded to Hackage,
http://hackage.haskell.org/cgi-bin/hackage-scripts/package/HTTP
Robust handling of ill-formed cookies + squash a bug in normalization of
certain proxy-bound requests would be the (minor) headlines of this release.
enjoy
Dusan Kolar wrote:
Dear all,
reading that
according the several style guides, lines shouldn't be too long
(longer than 78 characters).
http://www.cs.caltech.edu/courses/cs11/material/haskell/misc/haskell_style_guide.html
http://www.haskell.org/haskellwiki/Programming_guidelines
I
Daryoush Mehrtash wrote:
I am not sure I follow how the endofunctor gave me the 2nd functor.
As I read the transformation there are two catagories C and D and two
functors F and G between the same two catagories. My problem is that I only
have one functor between the Hask and List catagories.
Hello haskell-cafe,
I'm running into what I think is a space leak. I've modified
external-sort-0.2 [0] to use tournament trees for merging, and
although the block sorting works in constant space, merging seems to
produce a space leak.
The external sort works by lazily consuming an input list,
On 21 Apr 2009, at 7:39 pm, Jason Dagit wrote:
Not really. Obviously some programs use the feature, but let us
restrict to interesting programs that have been shared with the world
and have some potential to receive maintenance.
Why?
You are, in effect, saying that my code has no value at
On 21 Apr 2009, at 8:20 pm, Edward Middleton wrote:
ghc 6.8.3 is /usr/bin/ghc on my office Mac, but nothing in the world
prevents there being some other program called ghc that would also
like to be there. Only by painstaking verification of a whole
bunch of applications together can one be
On 21 Apr 2009, at 11:36 pm, Achim Schneider wrote:
Richard O'Keefe o...@cs.otago.ac.nz wrote:
Some of the right questions are
- how many potential whatever users would need to have
whatever installed on _some_ machine they do NOT have
administrator access to?
Irrelevant.
How van
wren ng thornton w...@freegeek.org wrote:
There is a deeper reason. Much work in typography has shown
that humans read text best when it's around 76
characters wide; if things get narrower than that then
cohesion is lost, if things get wider then it takes a long
time to acquire the
On Tue, Apr 21, 2009 at 8:34 PM, Richard O'Keefe o...@cs.otago.ac.nz wrote:
On 21 Apr 2009, at 7:39 pm, Jason Dagit wrote:
Not really. Obviously some programs use the feature, but let us
restrict to interesting programs that have been shared with the world
and have some potential to receive
On 22 Apr 2009, at 2:53 am, Richard Kelsall wrote:
Dusan Kolar wrote:
...
Or is the reason much deeper? Or, is the bound set to 78 characters
just because it is as good number as any other?
...
As a little historical detour I think the 80 character limit goes back
to 1928 when IBM designed
On Tue, Apr 21, 2009 at 8:34 PM, Richard O'Keefe o...@cs.otago.ac.nz wrote:
On 21 Apr 2009, at 7:39 pm, Jason Dagit wrote:
Not really. Obviously some programs use the feature, but let us
restrict to interesting programs that have been shared with the world
and have some potential to receive
Hi,
I'll be trying Sigbjorns haskell-dotnet package together with LINQ.
What's a good book for LINQ?
Günther
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Haskell-Cafe@haskell.org
http://www.haskell.org/mailman/listinfo/haskell-cafe
Hi
It's not too hard. You wanted a function that converted Maybe a - a,
you just Hoogle for it:
http://haskell.org/hoogle/?hoogle=Maybe+a+-+a
Thanks
Neil
On Wed, Apr 22, 2009 at 2:07 AM, michael rice nowg...@yahoo.com wrote:
Got it! I figured there must be some way to unpack it.
My
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