On 2007-10-12, Brandon S. Allbery KF8NH [EMAIL PROTECTED] wrote:
On Oct 12, 2007, at 17:38 , Lihn, Steve wrote:
Installing: --prefix=~/cabal/lib/haddock-0.8/ghc-6.4
This looks suspicious to me: the ~ metacharacter is only
understood by shells, and only in certain circumstances (i.e.
Don Stewart wrote:
allbery:
Didn't someone already prove all monads can be implemented in terms
of Cont?
Cont and StateT, wasn't it?
And the schemers have no choice about running in StateT :)
You sure? I want to see the proof :)
Last time I stumbled upon something like this, the proof
On 2007-10-12, Dan Weston [EMAIL PROTECTED] wrote:
applyNtimes f n | n 0 = f . applyNtimes f (n-1)
| otherwise = id
Why not some variant of:
applyNtimes f n = foldl' (.) id (replicate n f)
--
Aaron Denney
--
___
Haskell-Cafe
Lihn, Steve [EMAIL PROTECTED] writes:
Hi,
I have been hacking the Haskell installation a few days on Redhat Linux.
GHC 6.6 - 6.6.1 - Lambdabot does not work.
[...]
Anyway, now my question is, how do I thoroughly clean up Haskell? (And
maybe try again after a few days of rest.)
Is
On Fri, 2007-10-12 at 20:25 -0700, Stefan O'Rear wrote:
On Sat, Oct 13, 2007 at 12:09:57AM +0200, ntupel wrote:
setup :: (Ord a, IArray a2 a, IArray a1 e, Num a) = [e] - [a] - (a1 Int
e, a1 Int e, a2 Int a)
calcAlias :: (Ord e, Num e, IArray a e, Ix i, IArray a2 e1, IArray a1 e1)
= a2 i
Yes that would be cool. Similarly, Haskell could also be used to create
something like http://www.soundspectrum.com/g-force. Would be cool to
translate the vector-field code to the GPU, and that has already been
done in Haskell (Vertigo?)
Conal Elliott wrote:
sounds like great fun to me.
Dan: Sorry, I forgot to Reply to All.
On 12/10/2007, Dan Weston [EMAIL PROTECTED] wrote:
...
We don't want to make an intermediate list of zeroes and append, since
that could be wasteful. Just keep adding a zero to the head of our list
until it gets big enough. Our list is not copied (i.e. it
On Oct 13, 2007, at 3:51 , Aaron Denney wrote:
On 2007-10-12, Brandon S. Allbery KF8NH [EMAIL PROTECTED] wrote:
On Oct 12, 2007, at 17:38 , Lihn, Steve wrote:
Installing: --prefix=~/cabal/lib/haddock-0.8/ghc-6.4
This looks suspicious to me: the ~ metacharacter is only
understood by
On Oct 13, 2007, at 6:52 , ntupel wrote:
On Fri, 2007-10-12 at 20:25 -0700, Stefan O'Rear wrote:
On Sat, Oct 13, 2007 at 12:09:57AM +0200, ntupel wrote:
setup :: (Ord a, IArray a2 a, IArray a1 e, Num a) = [e] - [a] -
(a1 Int e, a1 Int e, a2 Int a)
calcAlias :: (Ord e, Num e, IArray a e, Ix
On 10/12/07, PR Stanley [EMAIL PROTECTED] wrote:
Hi
failure :: (Parser a) failure = \inp - []
The code might contain some syntax errors and I'd be grateful for any
corrections.
What is a dual parser failure?
You should probably put the definition on a separate line, thus:
failure ::
Andrew Coppin wrote:
I was actually thinking more along the lines of a programming language
where you can just write
head :: (n 1) = List n x - x
Current GHC can approximate this with a GADT:
==
{-# OPTIONS -fglasgow-exts #-}
module SafeHead where
Hello,
Didn't someone already prove all monads can be implemented in terms
of Cont?
Cont and StateT, wasn't it?
And the schemers have no choice about running in StateT :)
You sure? I want to see the proof :)
I think this is referring to Andrzej Filinski's paper Representing
Layered
On Sat, 2007-10-13 at 09:56 -0400, Brandon S. Allbery KF8NH wrote:
Now you need to start forcing things; given laziness, things tend to
only get forced when in IO, which leads to time being accounted to
the routine where the forcing happened. If random / randomR are
invoked with large
jeff p wrote:
I think this is referring to Andrzej Filinski's paper Representing
Layered Monads in which it shown that stacks of monads can be
implemented directly (no layering) by using call/cc and mutable state.
I have been unable to see how to bring its crucial reify and reflect
to
On Oct 13, 2007, at 11:40 , ntupel wrote:
On Sat, 2007-10-13 at 09:56 -0400, Brandon S. Allbery KF8NH wrote:
Now you need to start forcing things; given laziness, things tend to
only get forced when in IO, which leads to time being accounted to
the routine where the forcing happened. If
On Saturday 13 October 2007, Albert Y. C. Lai wrote:
jeff p wrote:
I think this is referring to Andrzej Filinski's paper Representing
Layered Monads in which it shown that stacks of monads can be
implemented directly (no layering) by using call/cc and mutable state.
I have been unable to
On Sat, 2007-10-13 at 12:42 -0400, Brandon S. Allbery KF8NH wrote:
Your apparently simple StdGen argument is actually a sort of program
state (represented by unevaluated thunks, not by a state monad; see
below) which gets altered with every invocation of random. If
nothing is forced
On Oct 13, 2007, at 13:30 , ntupel wrote:
On Sat, 2007-10-13 at 12:42 -0400, Brandon S. Allbery KF8NH wrote:
Your apparently simple StdGen argument is actually a sort of program
state (represented by unevaluated thunks, not by a state monad; see
below) which gets altered with every invocation
On Sat, 2007-10-13 at 13:35 -0400, Brandon S. Allbery KF8NH wrote:
For starters, look into seq. Try applying it to any expression
using a generated random number. This should force evaluation to
occur somewhere other than when random is trying to figure out what
StdGen value it's been
Hi
do, what's its role?
I know a few uses for it but can't quite understand the semantics -
e.g. do putStrLn bla bla
So, what does do, do?
Thanks, Paul
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On Sat, 13 Oct 2007, PR Stanley wrote:
Hi
do, what's its role?
I know a few uses for it but can't quite understand the semantics - e.g. do
putStrLn bla bla
So, what does do, do?
It's syntactic sugar.
http://www.haskell.org/onlinereport/exps.html#sect3.14
Andrew Coppin wrote:
Is there a way to get rid of . and .. in the results?
Brandon S. Allbery wrote:
Manual filtering is always required, whether C, Perl, Haskell, etc.
I dunno, maybe python filters them for you or something.
Correct, Python filters them out. This is clearly the correct
On 10/13/07, PR Stanley [EMAIL PROTECTED] wrote:
Hi
do, what's its role?
I know a few uses for it but can't quite understand the semantics -
e.g. do putStrLn bla bla
So, what does do, do?
In this example, do doesn't do anything. do doesn't do anything to a
single expression (well, I think
ntupel wrote:
Thanks for your reply Stefan. Unfortunately I could measure only a
relatively small improvement by changing to concrete types
the sample code was about one second faster when compiled with -O2.
Profiling again indicated that most time was spend in random and randomR
GHC
isaacdupree:
ntupel wrote:
Thanks for your reply Stefan. Unfortunately I could measure only a
relatively small improvement by changing to concrete types
the sample code was about one second faster when compiled with -O2.
Profiling again indicated that most time was spend in random and
On Sat, 13 Oct 2007, Yitzchak Gale wrote:
Andrew Coppin wrote:
Is there a way to get rid of . and .. in the results?
Brandon S. Allbery wrote:
Manual filtering is always required, whether C, Perl, Haskell, etc.
I dunno, maybe python filters them for you or something.
Correct, Python
On Sat, 13 Oct 2007, Henning Thielemann wrote:
On Sat, 13 Oct 2007, PR Stanley wrote:
Hi
do, what's its role?
I know a few uses for it but can't quite understand the semantics - e.g. do
putStrLn bla bla
So, what does do, do?
It's syntactic sugar.
On Fri, 2007-10-12 at 16:20 -0700, Dan Weston wrote:
I like that name, and will henceforth use it myself until someone sees
fit to add it to the Prelude!
Maxime Henrion wrote:
Isaac Dupree wrote:
Dan Weston wrote:
applyNtimes :: (a - a) - Int - a - a
This sounds like it should be
PR Stanley wrote:
Hi
do, what's its role?
I know a few uses for it but can't quite understand the semantics - e.g.
do putStrLn bla bla
So, what does do, do?
On Sat, 13 Oct 2007, Henning Thielemann wrote:
It's syntactic sugar.
http://www.haskell.org/onlinereport/exps.html#sect3.14
On Sat, Oct 13, 2007 at 23:27:13 +0200, Yitzchak Gale wrote:
Andrew Coppin wrote:
Is there a way to get rid of . and .. in the results?
Brandon S. Allbery wrote:
Manual filtering is always required, whether C, Perl, Haskell, etc.
I dunno, maybe python filters them for you or something.
On Sat, 2007-10-13 at 14:37 -0700, Don Stewart wrote:
I've seen similar results switching to the SIMD mersenne twister C
implementation for randoms:
http://www.math.sci.hiroshima-u.ac.jp/~m-mat/MT/SFMT/index.html
If there's interest, I can package up the bindings for hackage.
I
Thanks for the very clear explanation. More questions:
What is the role of ?
How is different to =? I am aware that = is used for
sequencing parsers but that's all I know about it.
Thanks, Paul
At 22:28 13/10/2007, you wrote:
On 10/13/07, PR Stanley [EMAIL PROTECTED] wrote:
Hi
do, what's
Disclaimer: I'm explaining all of this in terms of actions, which
are only one way of looking at monads, and the view only works for
certain ones (IO, State, ...). Without futher ado...
An action does two things: it has a side-effect and then it has a
return value. The type IO Int is an I/O
Luke Palmer wrote:
Using this you can do more complex actions, like, for instance, adding
two numbers:
readLine = (\x - readLine = (\y - print (x + y)))
Take a moment to grok that...
Which you might like to write:
do x - readLine
y - readLine
print (x + y)
you can
Don Stewart wrote:
I've seen similar results switching to the SIMD mersenne twister C
implementation for randoms:
http://www.math.sci.hiroshima-u.ac.jp/~m-mat/MT/SFMT/index.html
If there's interest, I can package up the bindings for hackage.
looks nice... at least for those of us who
Yitzchak Gale wrote:
Python also has os.walk, a very convenient functional (sort of)
tool for recursing through directories. (It sounds trivial, but
it is not, there are enough annoying details that this function
saves huge amounts of time.) Very embarrassing that Haskell
is missing this.
See
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