At 4:30 PM -0700 8/5/12, Matthew wrote:
On Sun, Aug 5, 2012 at 12:32 AM, Henk-Jan van Tuyl wrote:
On Sun, 05 Aug 2012 03:21:39 +0200, Matthew wrote:
I've got a function which takes in two chars, describing a playing
card and a suit. An example would be 4C or TH for a 4 of Clubs or a
Ten
Hi, Cafe,
My wife, a biologist, will attend a conference outside Helsinki in
mid-September. I've decided to accompany her on the trip to Finland.
Are there any Haskellers in the area who might be interested in an
informal meetup?
I'd also welcome any suggestions on what to see, do, eat, etc
For the following expression, I would consider a True result a false positive:
let x = x :: Int in x == x
Dean
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At 8:45 PM -0700 11/3/10, Peter Schmitz wrote:
I have a program (test.hs):
module Main (main) where
import System.Exit
main :: IO ExitCode
main = do
return (ExitFailure 1)
In another program, I invoke it via 'system':
exitCode <- system ".\\test.exe"
case (exitCode) of
At 4:43 PM -0400 10/6/10, Sterling Clover wrote:
On Oct 6, 2010, at 5:39 AM, Simon Marlow wrote:
A slightly different suggestion from Simon PJ and myself (we
agreed on something syntax-related :-) is the following:
\case 1 -> f
2 -> g
where the two-token sequence '\ case' introdu
At 3:36 AM -0600 10/5/10, Luke Palmer wrote:
On Mon, Oct 4, 2010 at 9:04 PM, Dean Herington
wrote:
With respect to "datatype destructing" functions, the Prelude has:
maybe :: b -> (a -> b) -> Maybe a -> b
either :: (a -> c) -> (b -> c) -> Either a b -
At 12:05 PM +0200 10/4/10, Christopher Done wrote:
On 4 October 2010 10:55, Bulat Ziganshin wrote:
Hello Ketil,
Monday, October 4, 2010, 11:30:48 AM, you wrote:
Prelude> (if then "Haskell" else "Cafe") False
lambda-if is easily implemented in terms of usual functions.
and we even have
At 8:29 PM -0400 8/2/10, Brandon S Allbery KF8NH wrote:
On 8/2/10 19:59 , aditya siram wrote:
Agreed. In fact I have the most trouble imagining what Haskell code looked
like before monads.
IIRC the type of main was something like [Request] -> [Response].
Actually, the Haskell 1.2 report (
At 11:53 AM -0700 7/4/10, Michael Mossey wrote:
Wondering if I could get some suggestions for coding this problem.
A musical document (or "score") consists primarily of a list of
measures. A measure consists primarily of lists of "items". We'll
consider only one kind of item: a note. Items hav
Does anyone know if I can bring a 64-bit (long long or unsigned long
long) value from C-land into Haskell via hsc2hs? #const on such a
value seems to provide only the low 32 bits, at least in my
environment (Haskell Platform 2009.2.0.2 on Windows). I've tried to
create a 64-bit variant of #co
Is there any reason not to use the more standard "uninterruptible"
instead of "noninterruptible"?
Dean
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At 2:53 PM -0800 2/18/10, Yves Parès wrote:
Ben Franksen wrote:
You can leave them "unsafe" if you are sure that
1) they do not call (back) any function in your program
2) they do not block (or not long enough that it bothers you)
Otherwise they are no less safe that the "safe" calls. If (1) i
At 11:00 AM + 11/17/09, Simon Marlow wrote:
I've just uploaded deepseq-1.0.0.0 to Hackage
http://hackage.haskell.org/package/deepseq
This provides a DeepSeq class with a deepseq method, equivalent to
the existing NFData/rnf in the parallel package. I'll be using this
in a newly revampe
At 4:25 PM +1200 6/17/09, Richard O'Keefe wrote:
On 17 Jun 2009, at 2:01 pm, Richard O'Keefe wrote:
On second thoughts,
let strings = "" : [pref++[last] | pref <- strings, last <- ['a'..'z']]
in tail strings
seems more Haskellish than the stupidly clever counting-based
code I had in mind.
At 10:12 PM -0700 5/13/09, Don Stewart wrote:
heringtonlacey:
At 9:59 PM -0700 5/13/09, Don Stewart wrote:
heringtonlacey:
I have a large body of C/C++ code at work that I'd like to be able
to access from Haskell via FFI. Because the interface to this code
is broad, hsffig would seem
At 9:59 PM -0700 5/13/09, Don Stewart wrote:
heringtonlacey:
I have a large body of C/C++ code at work that I'd like to be able to
access from Haskell via FFI. Because the interface to this code is
broad, hsffig would seem to be ideal for the task.
I've run across one serious hitch, thou
I have a large body of C/C++ code at work that I'd like to be able to
access from Haskell via FFI. Because the interface to this code is
broad, hsffig would seem to be ideal for the task.
I've run across one serious hitch, though. The existing #include
file graph is complicated and ends up d
At 7:17 PM +0200 5/2/09, Nicolas Martyanoff wrote:
Content-Type: multipart/signed; micalg=pgp-sha1;
protocol="application/pgp-signature"; boundary="ibTvN161/egqYuK8"
Content-Disposition: inline
Hi,
I don't think I already presented myself; I'm Nicolas, a 23y french
student, trying to le
a ghc that doesn't statically link GMP ;-)
Dave
On Sun, Mar 15, 2009 at 9:03 PM, Alan Mock
<<mailto:docm...@gmail.com>docm...@gmail.com> wrote:
By default GMP builds for x86_64. Do ./configure ABI=32 to build
32-bit libraries for GHC.
On Mar 15, 2009, at 10:54 PM,
I'm trying to install GHC 6.10.1 on Mac OS X 10.5 (PowerPC). I
installed Xcode 3.1.2. I built libgmp 4.2.4 and installed it in
/usr/local/lib. When I do "./configure" in GHC's dist directory,
however, I get:
bash-3.2$ ./configure
checking build system type... powerpc-apple-darwin9.6.0
check
At 8:45 PM + 3/14/09, R J wrote:
Can someone provide the induction-case proof of the following identity:
foldl (-) ((-) x y) ys = (foldl (-) x ys) - y
If foldl is defined as usual:
foldl :: (b -> a -> b) -> b -> [a] -> b
foldl f e [] = e
foldl f e (x
I like Tillmann's cleanup. Here's another variation (warning: untested code).
filter3 :: (FilterWindow3 -> Double) -> Dataset -> Dataset
filter3 f3 [] = []
filter3 f3 dss@(d:ds) = map f3 $ zip3 (d:dss) dss (shiftForward dss)
-- Given a nonempty list, drops the first element and
-- dupli
Date: Mon, 24 Dec 2007 01:44:16 -0500
To: "Galchin Vasili" <[EMAIL PROTECTED]>, haskell-cafe@haskell.org
From: Dean Herington <[EMAIL PROTECTED]>
Subject: Re: [Haskell-cafe] more on the "Beautiful Concurrency"
function "withdraw" application ...
Cc:
Bc
At 12:19 AM -0600 12/24/07, Galchin Vasili wrote:
module Main where
import Control.Concurrent.STM
import Control.Concurrent
import System.Random
type Account = TVar Int
transfer :: Account -> Account -> Int -> IO ()
transfer from to amount
= atomically (do {deposit to amount;
Thanks, Tom, for a nice description of lazy evaluation.
Besides the minor things Derek pointed out, there's one more subtle
but important thing to correct:
At 7:29 AM + 11/29/07, Thomas Davie wrote:
$! is the special case, which means strictly apply. It evaluates
its argument first, *t
The Haddock documentation for Text.XHtml (at
http://www.haskell.org/ghc/docs/latest/html/libraries/xhtml/Text-XHtml.html)
refers to
http://www.cse.ogi.edu/~andy/html/intro.htm, but that link is broken.
Does anyone know where to find the intended document?
___
At 8:13 PM +0300 6/30/07, Esa Ilari Vuokko wrote:
On 6/30/07, Duncan Coutts <[EMAIL PROTECTED]> wrote:
On Fri, 2007-06-29 at 23:22 -0400, Dean Herington wrote:
>Date: Mon, 25 Jun 2007 20:19:50 -0400
>>With gtk2hs, using "-optl-mwindows" as a command line option f
Date: Mon, 25 Jun 2007 20:19:50 -0400
To: Jens Fisseler <[EMAIL PROTECTED]>
From: Dean Herington <[EMAIL PROTECTED]>
Subject: Re: [Haskell-cafe] avoiding command window with wxHaskell on Windows?
Cc: haskell-cafe@haskell.org, [EMAIL PROTECTED]
At 10:10 PM +0200 6/23/07, Jens Fissele
At 10:10 PM +0200 6/23/07, Jens Fisseler wrote:
On Sat, 23 Jun 2007, Dean Herington wrote:
But if I double-click the .exe file, I get a command window that
hangs around
(but doesn't appear to do anything, fortunately) until the program
terminates.
How can I avoid this command w
I'm experimenting with wxHaskell. I created a small program with it
on Windows. (Well, small in source form, not so small in binary form
:-) The program runs fine when invoked at a Windows command line.
But if I double-click the .exe file, I get a command window that
hangs around (but doesn'
Has anyone built a library providing an interface to WMI (Windows
Management Instrumentation) in Haskell?
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At 12:42 AM +0400 2/19/07, David Tolpin wrote:
On Mon, 19 Feb 2007 00:30:47 +0400, Sebastian Sylvan
<[EMAIL PROTECTED]> wrote:
Well, I guess the H98 report would be a good start. But there are
multiple tutorials on type classes that will cover this, most of which
are available from haskell.or
At 11:02 AM +0200 1/10/07, Yitzchak Gale wrote:
Unfortunately, the current situation is that State is only
available as a lazy monad, and StateT is only available
as a strict monad.
[...]
The obvious solution would be to have available
both a lazy and a strict version of each monad: State,
S
I can't seem to figure out how to achieve strictness in the context
of the State monad. Consider:
import Control.Monad.State
try count = print final
where (_,final) = runState prog 0
prog = sequence_ (replicate count tick)
tick :: State Int Int
tick = do n <- get
At 12:25 PM +1000 12/4/06, Tony Morris wrote:
I wish to pass a 2 dimensional array to use in a back-tracking
algorithm. Since I will be doing lots of inserts, a Data.Array is
unsuitable. It seems that a Map Int (Map Int a) is the most suitable
structure, but this seems cumbersome.
Is there anyt
At 11:58 AM -0700 4/2/06, Jared Updike wrote:
Is there a common way (standard libs, higher order) to express the
lambda part below? It's not particulary complicated but I think it is
not higher-order enough
unionBy (\x y -> fst x == fst y) listOfPairs1 listOfPairs2
Something like "distribute
At 11:44 PM + 9/10/05, Thomas Spriggs wrote:
From: gary ng <[EMAIL PROTECTED]>
fac n = foldr (\x g n -> g (x*n)) id [1..n] 1
Would appreciate if someone can knock on my head and
tell me what is going on in it.
Well, here goes. The way the lambda function/foldr thing evaluates,
the result
At 9:45 PM +0400 9/4/05, Dmitry Vyal wrote:
Donald Bruce Stewart wrote:
Maybe your loop does no allocations, so the scheduler can't get in and do a
context switch. You could put the computation in an external
program, and run
it over a fork, using unix signals in the external program to kill
At 3:39 PM + 8/22/05, Dinh Tien Tuan Anh wrote:
Hi,
Basically, my program has 7 threads for 7 rules
Rule1
Rule2
..
..
..
and they all use pattern-mattching (a rule MUST be evaluated by a thread)
The problem is there are some overlapping rules, which match the
same pattern and diifferent
At 7:23 PM -0400 6/9/05, Samuel Bronson wrote:
On 05/06/05, Dean Herington <[EMAIL PROTECTED]> wrote:
I believe you're describing:
http://portal.acm.org/citation.cfm?doid=581478.581482 .
I don't suppose you know of any place to get it *free*?
I found it online at: http:/
At 8:34 PM +0200 6/5/05, Gracjan Polak wrote:
Some time ago I read a beautiful paper about variables that had
their dependencies automatically tracked and could trigger
recalculation when changed. Prototype was implemented in OCaml,
then reimplemented in Haskell (using monads). I would like
Please forgive this interruption...
E-mail I try to send to frequent contributor Henning Thielemann
<[EMAIL PROTECTED]> (which apparently expands to
<[EMAIL PROTECTED]>) bounces back to me with error message
"Domain blocked owing to abuse.". Is there another address at which
Henning can be r
At 5:27 PM -0800 2/18/05, Isaac Jones wrote:
John Goerzen <[EMAIL PROTECTED]> writes:
Here's an alternative:
module Main where
(snip john's version)
And what list would be complete without a points-free version. It
doesn't operate on stdin, though like John's does:
pointsFreeCat :: IO ()
pointsF
Does anyone out there have a prebuilt Haskell system for AIX? I'm
trying to find the easiest route to running a Haskell interpreter on
AIX (5.1 and 5.2).
Dean
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At 4:27 AM + 2003/11/06, Patty Fong wrote:
data Music
= Note Pitch Octave Duration
| Silence Duration
| PlayerPar Music Music
| PlayerSeq Music Music
| Tempo (Ratio Int) Music
data Pitch = Cf | C | Cs
type Octave = Int
type Duration = Ratio Int
foldMusic
At 11:15 AM -0500 2003/10/31, Harris, Andrew wrote:
> Hi -
> I am trying to work out how the following function using "fix" is
> evaluated. I am hoping someone could look at my step-by-step breakdown
> of how I think evaluation works and see if I'm correct. My main
> question is how the o
I've long thought that I/O buffering behavior--not just in Haskell, but
in most places I've encountered it--was unnecessarily complicated.
Perhaps it could be simplified dramatically by treating it as strictly a
performance optimization. Here's a sketch of the approach.
Writing a sequence of
On Wed, 30 Jul 2003, Dennis Sidharta wrote:
> Hi again,
>
> I have tried to play around with MVar today, but
> still... I did not see how to synchronize MVar without
> the help of forkIO, and then explicitly call yield ::
> IO (). But then, if I use forkIO I will create "daemon
> threads" that wi
I've thought for a while that it would be nice to have a shorthand for `if` /
`else if` chains. For example:
if a < b then "less"
else if a == b then "equal"
else "greater"
can be rendered with more structure as:
case () of _ | a < b -> "less"
| a == b-> "equal"
On Fri, 21 Feb 2003, M. Parker wrote:
> I'm a real newbie to Haskell, and I'm having trouble with a particular problem
> dealing with higher-order functions.
>
> Exercise 5.9 in Hudak's "School of Expression" asks us to write a function,
> "makeChange," s.t. it makes change for a given amount u
Ah, I see. Finite maps might be appropriate, then. Here's a sketch of
how you might implement arraylike objects with finite maps.
-- Array-like objects built from FiniteMaps
-- Dean Herington, Feb. 22, 2003
module FMArray (FMArray, fmArray, get, set, update) where
import Array
i
[moved to haskell-cafe]
While I largely agree with what Nils said, it does seem that arrays are a good match
for your application. It is true, unfortunately, as you're discovering, that
mutable arrays are awkward in a pure functional language. I think the most
appropriate way to deal with them w
On Thu, 13 Feb 2003, David Roundy wrote:
> On Thu, Feb 13, 2003 at 01:21:35PM -0500, Dean Herington wrote:
> > Here's another way to sugar if-then-else that works like C's ?: and Lisp's cond:
> >
> > import Monad (liftM3)
> > import Directory (doesFileE
Here's another way to sugar if-then-else that works like C's ?: and Lisp's cond:
import Monad (liftM3)
import Directory (doesFileExist, doesDirectoryExist)
infix 1 ?, ??
(?) :: Bool -> a -> a -> a
(c ? t) e = if c then t else e
(??) :: (Monad m) => m Bool -> m a -> m a -> m a
(??) = liftM3 (?)
The MArray class in Data.Array.MArray is a very nice abstraction.
However, when creating an array whose type partakes of MArray, say
STUArray, I find myself defining and using a type-specific creation
function, such as:
newSTUArray :: (MArray (STUArray s) e (ST s), Ix i)
=> (i, i) -> e
On Fri, 24 Jan 2003, Sarah Thompson wrote:
> I've noticed some interesting behaviour:
>
> Prelude Control.Exception> try (return (error "e"))
> Prelude Control.Exception> it
> Right *** Exception: e
>
> It would appear that when the result of this function is evaluated, the
> exception fires dur
Martin Huschenbett wrote:
> 2.) What are CVars for?
Originally, `putMVar` on a full MVar was an error. That meant that a
single MVar was not enough to implement a one-element channel. So, a
CVar was a pair of MVars that implemented a one-element channel. (See
the paper "Concurrent Haskell" by
Why doesn't Concurrent Haskell suit your needs?
Dean
Dusan Kolar wrote:
> Hello,
>
>My question/wish is maybe naive, but anyway:
> Is there a library (not a language extension, like
> Concurrent Haskell, Glasgow Parallel Haskell, ...) enabling
> to run two functions in parallel, possibly in
21, 2002 at 10:07:12AM -0500, Dean Herington wrote:
> > "Mike T. Machenry" wrote:
> >
> > > Andrew and list,
> > >
> > > I am a beginer. I really don't know what I would do if I derived
> > > Color from Enum. You say I could creat
"Mike T. Machenry" wrote:
> Andrew and list,
>
> I am a beginer. I really don't know what I would do if I derived
> Color from Enum. You say I could create elements that way. Is there
> some simple example someone could post to the list? Thank you for
> your help.
Here's one way to generate ran
On Wed, 23 Oct 2002, Jason Smith wrote:
> Hi All
>
> I don't know what I'm doing wrong here but for some reason no matter what esoteric
>command line option I seem to be able to dream up I can get ghc to include IOExts..I
>want to use the side-affect IO commands but cannot.
>
> I am using ghc-
Andrew J Bromage wrote:
> There's also a much uglier solution which I occasionally use if I
> need an "ad hoc" global variable. Rather than using IORefs, I use
> Strings as keys. The code is here:
>
> http://cvs.sourceforge.net/cgi-bin/viewcvs.cgi/hfl/hfl/ioext/
I'm not sure why you co
: Histo -> Char -> Histo
> tally histo ch = if isAlpha ch then addToFM_C (+) histo (toLower ch) 1
>else histo
> report :: Histo -> String
> report histo = unlines [ line ch | ch <- ['a'..'z'] ]
> where line
If you're using GHC, take a look at module Readline in the util package
(http://www.haskell.org/ghc/docs/latest/set/readline.html). I don't know
which other Haskell systems support this module.
Dean Herington
On Mon, 25 Feb 2002, Rich wrote:
> Hi,
>
> I'm writin
You have an extra `show` in the `Show` instance for `Out`.
Change `show x` to `x` there.
On Wed, 30 Jan 2002, Shawn P. Garbett wrote:
> -BEGIN PGP SIGNED MESSAGE-
> Hash: SHA1
>
> I've been fiddling with the example in section 10.2 of Bird's book,
> _Introduction_to_Functional_Programm
[EMAIL PROTECTED] wrote:
> There's another piece to this question that we're overlooking, I
> think. It's not just a difference (or lack thereof) in precedence, it's the
> fact that parentheses indicate application in Python and many other
> languages, and a function name without parenthe
>
readsA = map (\(a,t)-> (Prst a,t)) (readsPrec p s')
See section D.4 of the Haskell report for information on 'readsPrec',
'readList', 'showPrec', and 'showList'.
Dean Herington
I can't seem to find an easily printable (i.e., not HTML-in-many-pieces)
version of the documentation for the Hugs-GHC extension libraries. Have
I overlooked it?
Thanks.
Dean Herington
[EMAIL PROTECTED]
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