On 31/01/07, David House [EMAIL PROTECTED] wrote:
dw :: (a - Bool) - [a] - [a]
dw p = reverse . fst . foldl comb ([],False)
where comb (xs,done) x | done = (x:xs, True)
| p x = (xs, False)
| otherwise = (x:xs, True)
I forgot to
[sorry, this was meant to go to the list]
On Wednesday 31 January 2007 00:40, Bulat Ziganshin wrote:
Saturday, January 27, 2007, 12:00:11 AM, you wrote:
and support operational reasoning, i.e. creating and understanding
programs by mentally modeling their execution on a machine. This form
Quoth Magnus Therning, nevermore,
I'm not sure how a functional recipe would look, maybe something like
this:
White_sauce is a combination of ... .
Chopped_onions is onions cut into small pieces.
White_sauce_with_chopped_onions is the combination of white_sauce and
chopped_onions.
Bryan Donlan wrote:
{-# NOINLINE hDevRandom #-}
hDevRandom = unsafePerformIO $ openFile /dev/random ReadMode
I wrote:
The NOINLINE guarantees that openFile is called only
once. But does it guarantee that openFile is NOT called
if we do not need it? We could check what the compilers
actually
I'm curious, why doesn't Data.ByteString.Lazy.Char8 have the functions
for searching for substrings that Data.ByteString.Char8 has (isPrefixOf,
isSuffixOf, isSubstringOf, findSubstring and findSubstrings)?
/M
--
Magnus Therning (OpenPGP: 0xAB4DFBA4)
[EMAIL PROTECTED]
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Paul Moore
catcher :: DBException - DBM mark Session ()
catcher x = do
liftIO $ putStrLn $ show x
main = do
withSession (connect ... ... ...) ( do
catchDB (do ...
)
catcher
)
But
On Wed, Jan 31, 2007 at 07:46:15PM +0300, Bulat Ziganshin wrote:
Wednesday, January 31, 2007, 12:01:16 PM, you wrote:
there are also many other similar issues, such as lack of good syntax
for for, while, break and other well-known statements,
On the other hand you have an ability to
On 1/31/07, Kirsten Chevalier [EMAIL PROTECTED] wrote:
On 1/31/07, Bill Wood [EMAIL PROTECTED] wrote:
On Wed, 2007-01-31 at 19:51 +1100, Donald Bruce Stewart wrote:
. . .
foldl (\water dish - wash water dish) soapywater dishes :: [Dishes]
Nice example. First, note that you can't
On Thu, 2007-02-01 at 10:47 +0300, Bulat Ziganshin wrote:
Hello Duncan,
Thursday, February 1, 2007, 3:39:16 AM, you wrote:
Can anyone see a real serialisation use case that needs a monad for the
serialisation side? I'd thought I had an example, but I was wrong.
my program,
The question is --- how would an expert describe such a process? Would a
professional chef give instructions in the functional or imperative
style?
I think a sufficiently expert chef would not even need the functional
style. Everything would be declarative.
Dave Thomas (of Pragmatic
neil:
The question is --- how would an expert describe such a process? Would a
professional chef give instructions in the functional or imperative
style?
I think a sufficiently expert chef would not even need the functional
style. Everything would be declarative.
Dave Thomas (of
Hi Andrew,
You wrote:
combine :: [Int] - [Int] - [[Int]]
combine [] _ = []
combine (x:xs) ys = (take x ys) : (combine xs (drop x ys))
...A much more experienced haskeller told me he
preferred to write it like this:
combine' :: [Int] - [Int] - [[Int]]
combine' xs ys = snd $ mapAccumL aux ys xs
Hello Tomasz,
Thursday, February 1, 2007, 1:15:39 PM, you wrote:
while (hGetBuf h buf bufsize == bufsize)
crc := updateCrc crc buf bufsize
break if crc==0
print crc
inContT $ callCC $ \break - do
flip execStateT 0 $ do
whileM (liftM (== bufsize) (hGetBuf h
On 31/01/07, Andrew Wagner [EMAIL PROTECTED] wrote:
Like I said, I'm familiar with map, foldr, etc. But this is the
first time it's dawned on me that I need to think in more general
recursive patterns like this instead of simple, raw recursion. That
map and foldr aren't JUST a nice way of
Watching the questions go by in #haskell, a still fuzzy but possibly
pregnant idea popped up in my mind. Someone needed a nubBy function
that returned an unique list modulo an arbitrary function foo. Well,
in this case it wasn't arbitrary; he had a list of transposable
matrices and wanted an
Diego Navarro wrote:
Watching the questions go by in #haskell, a still fuzzy but possibly
pregnant idea popped up in my mind. Someone needed a nubBy function
that returned an unique list modulo an arbitrary function foo. Well,
in this case it wasn't arbitrary; he had a list of transposable
newtype Y = Y { unY :: X }
instance Eq Y where (==) = foo
nub' :: [X] - [X]
nub' = map unY . sort . map Y
Yes, I thought of that. I'm really thinking of how I can generalize
the Eq class so I dont have to go around manually lifting operations
that are already defined (like operations on
Yes, I thought of that. I'm really thinking of how I can generalize
the Eq class so I dont have to go around manually lifting operations
that are already defined (like operations on integers for modulo-n
rings)
(I do realize it's a lucky chance that the ordinary (+) and (*) work
so well on
Hi,
Does the Haskell community have an equivalent to C++ community's Boost
project with the aim of writing libraries for the eventual inclusion into
Haskell?
Thanks
-John
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Hi John,
Does the Haskell community have an equivalent to C++ community's Boost
project with the aim of writing libraries for the eventual inclusion into
Haskell?
We have:
1) MissingH - a nice staging ground for things that may end up in the
base library
2) Library submission process, to
Hello haskell-cafe,
i've just got ADSL connection here! it's slow (64k) and not cheap, but
at least it is completely different from dial-up i've used before
--
Best regards,
Bulat mailto:[EMAIL PROTECTED]
___
Haskell-Cafe
What part of Russia do you live in?
On Feb 1, 2007, at 1:23 PM, Bulat Ziganshin wrote:
Hello haskell-cafe,
i've just got ADSL connection here! it's slow (64k) and not cheap, but
at least it is completely different from dial-up i've used before
--
http://wagerlabs.com/
Hello John,
Thursday, February 1, 2007, 4:03:09 PM, you wrote:
Does the Haskell community have an equivalent to C++ community's
Boost project with the aim of writing libraries for the eventual inclusion
into Haskell?
i guess that the only reason why C++ people need such project is
because
Bulat Ziganshin wrote:
Hello John,
Thursday, February 1, 2007, 4:03:09 PM, you wrote:
Does the Haskell community have an equivalent to C++ community's
Boost project with the aim of writing libraries for the eventual inclusion
into Haskell?
The Haskell community is hosted on the wiki at
Hello Joel,
Thursday, February 1, 2007, 4:25:45 PM, you wrote:
What part of Russia do you live in?
Tatarstan. we make Kamaz here :) if you are interested, such
situation is very common for Russia - except for Moscow and a few
other largest cities, internet costs are very high.
you will stop
Hi,
I am trying to compile the GLR examples from Happy 1.16, but I get the
message that I am missing the data package. Where can I download it
from? I am using GHC 6.6
/pavel
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I would like to point out the importance of Cale Gibbard's
MonadRandom, beyond what is currently mentioned
on its wiki page:
http://www.haskell.org/haskellwiki/New_monads/MonadRandom
This monad makes it possible to write functions that
use randomness without having to specify in
advance whether
And we have reached the monadic equivalent of Schrodinger's cat.
On 1/31/07, Eric Y. Kow [EMAIL PROTECTED] wrote:
Dear Haskellers,
In the recent HWN, I noticed a new monad metaphor by Don Stewart:
Think of a monad as a spacesuite full of nuclear waste in the ocean next to a
container of
Bayley, Alistair wrote:
Al Falloon wrote:
what does withSession return if there is a DBException?
Well, whatever the handler returns, same as with any other exception
handler. Note that this must have the same type as whatever withSession
returns, and this constraint is enforced by the type
so are monads whats holding the nuclear waste or whats holding the apples?
;)
On 2/1/07, Frederick Ross [EMAIL PROTECTED] wrote:
And we have reached the monadic equivalent of Schrodinger's cat.
On 1/31/07, Eric Y. Kow [EMAIL PROTECTED] wrote:
Dear Haskellers,
In the recent HWN, I noticed
Hello Frederick,
Thursday, February 1, 2007, 6:11:32 PM, you wrote:
And we have reached the monadic equivalent of Schrodinger's cat.
yes, it's exact reason why we love monads - the appropriate fruits in
container are appeared depending on environment where it's used. you
send probabilistic
while (hGetBuf h buf bufsize == bufsize)
crc := updateCrc crc buf bufsize
break if crc==0
print crc
inContT $ callCC $ \break - do
flip execStateT 0 $ do
whileM (liftM (== bufsize) (hGetBuf h buf bufsize)) $ do
modifyM (updateCrc buf bufsize)
On 2/1/07, Donald Bruce Stewart [EMAIL PROTECTED] wrote:
So a big hello to any Ruby/Rails hackers lurking out there!
Free lambdas for all if you drop by #haskell...
I came to Haskell from Ruby the first time around, but didn't have
anything real to write in it so I lost steam somewhat. This
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Al Falloon
Bayley, Alistair wrote:
Al Falloon wrote:
what does withSession return if there is a DBException?
Well, whatever the handler returns, same as with any other exception
handler. Note that this must have the
Hello Claus,
Thursday, February 1, 2007, 6:34:23 PM, you wrote:
is it, though? what makes it longer are features that the original doesn't
have,
and what i don't need :)
I think. so how about a less ambitious translation, with crc in an MVar and a
while-loop that can be broken from the
One of the great strengths of Python is Boost.Python. Practitioners
say it's a major advantage of Python over Ruby, for example. So the
question is not whether there's a Boost in Haskell -- C++ and Haskell
are too different for it to have much meaning -- but whether there's
or going to
In The Monad.Reader - Issue 6, that just came out, there is a really
interesting article that uses a circular technique to implement an
assembly language in Haskell. The technique demonstrated seems
fascinating. Can someone point me to more resources on the topic?
A quick google search turned up
Hi Justin,
A quick google search turned up a couple of blogs and some papers -
but is there more out there?
http://news.cs.york.ac.uk/ftpdir/pub/colin/jfp97lw.ps.gz
Laziness, circularity and prime numbers all in one :)
Thanks
Neil
___
On 2/1/07, Donald Bruce Stewart [EMAIL PROTECTED] wrote:
So a big hello to any Ruby/Rails hackers lurking out there!
Free lambdas for all if you drop by #haskell...
I think we should also try to get some feedback about the learning
experience: what tutorials work best, and what don't? Do
Hi Justin,
In The Monad.Reader - Issue 6, that just came out, there is a really
interesting article that uses a circular technique to implement an
assembly language in Haskell. The technique demonstrated seems
fascinating. Can someone point me to more resources on the topic?
I believe the
Boost.Python is for extending Python with C++, or embedding Python in
C++. This is especially useful because it allows you to use Python as an
extension language for a C++ program.
Presumably Boost.Haskell would be for integrating Haskell code with C++,
which would of course be useful, but
Yet another higher order solution:
dropWhile' p0 xs = foldr f (const []) xs $ p0
where
f y ys p | p y = ys p
| otherwise = y : ys (const False)
Spencer Janssen
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David House wrote:
It was a great article though, seeing
fix's definition in terms of foldr was one of those mind-bending
moments which makes learning Haskell what it is.
It's nice to see so many new solutions posted in the cafe.
The great thing about Haskell is that it keeps on giving :)
On 2/1/07, Al Falloon [EMAIL PROTECTED] wrote:
Boost.Python is for extending Python with C++, or embedding Python in
C++. This is especially useful because it allows you to use Python as an
extension language for a C++ program.
Presumably Boost.Haskell would be for integrating Haskell code with
while (hGetBuf h buf bufzise .==. (return bufsize)) $ do
crc =: updateCrc crc buf bufsize
breakIf ((val crc) .==. (return 0)) `orElse` do
printM (val crc)
od
your solution is just to make lifted copy of each and every pure
operation. so one should define 2^n
Are (a - [b]) and [a - b] isomorphic? I'm trying to construct a function
f :: (a - [b]) - [a - b]
that is the (at least one-sided) inverse of
f' :: [a - b] - a - [b]
f' gs x = map ($ x) gs
It seems like it should be obvious, but I haven't had any luck with it yet.
Any help is greatly
I'm going through the Write Yourself a Scheme in 48 Hours
http://halogen.note.amherst.edu/~jdtang/scheme_in_48/tutorial/overview.html
tutorial. I like it a lot, but I have some concerns. Are the
exercises in the tutorial known to be solvable by mere mortals?
For instance:
Rewrite parseNumber
The 70's and early 80's were very different in terms of information
propagation. I really miss some the journals available back then,
because the editors really did their jobs, both in selecting and
helping to convey, information.
OO did get oversold. The same way that putting it on the internet
Shannon -jj Behrens wrote:
I'm going through the Write Yourself a Scheme in 48 Hours
http://halogen.note.amherst.edu/~jdtang/scheme_in_48/tutorial/overview.html
tutorial. I like it a lot, but I have some concerns. Are the
exercises in the tutorial known to be solvable by mere mortals?
The
High performance strings on the shootout:
http://shootout.alioth.debian.org/gp4/benchmark.php?test=sumcollang=all
interesting alternative programs
0.5 Haskell GHC #5 1.2990,880270
1.0 Clean 2.77600 136
2.0 C gcc
On Fri, 2 Feb 2007 06:46 am, Paul Johnson wrote:
I think we should also try to get some feedback about the learning
experience: what tutorials work best, and what don't? Do metaphors for
monads work?
Fwiw, here's an excerpt from something i wrote in my blog about monads (where
i've
This seems to make using tuples of various sizes easier (and can
also be applied to non-tuples). I think it more closely matches
how I describe something in spoken language (when I say second
its obvious what that means for any tuple size):
{-# OPTIONS_GHC -fglasgow-exts #-}
module Main where
See for examples of the usage of = A tour of the Haskell monad
functions, URL:
members.chello.nl/hjgtuyl/tourdemonad.html
On Fri, 02 Feb 2007 01:31:36 +0100, Shannon -jj Behrens [EMAIL PROTECTED]
wrote:
I'm going through the Write Yourself a Scheme in 48 Hours
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