Hello Claus,
Monday, March 12, 2007, 3:35:43 AM, you wrote:
the problems was mainly due to 2 factors:
1) readArray m (i,j)
yes, indeed. since we are dealing in bulk operations, we might as well take
advantage
of that, so dropping the repeated bounds-checks inside the loops makes a lot
of
The Maybe construction is very useful for explicitly handling
circumstances where the function cannot produce a sensible answer.
But how far should this notion be taken? When you're writing a function
which you realise may not produce what you want, in what circumstances
would you use a Maybe,
Hello all,
While using the very nice option combinator of Parsec recently, it
seemed to me that it would be useful to have a more specific kind of
combinator for optional tokens that wraps the token into a Maybe type.
So, that gives:
pmaybe :: GenParser tok st a - GenParser tok st
Hi
I notice that there's not much user-accessible documentation of what you
can expect GHC (or some other Haskell implementation) to do and not do
with a given piece of code.
Yhc/nhc/Hugs - nothing
GHC - inlining, simplification, fusion if you use the build in
functions in a specified way,
On Mon, Mar 12, 2007 at 11:24:48AM +0100, Maxime Henrion wrote:
While using the very nice option combinator of Parsec recently, it
seemed to me that it would be useful to have a more specific kind of
combinator for optional tokens that wraps the token into a Maybe type.
So, that gives:
Hi
head []
return Nothing? I guess it's a bit of a silly suggestion, but it helps
to highlight why we use Maybe in the first place. So --- where's the
cutoff point in your code?
If that is what you want, then see my Safe library:
1) readArray m (i,j)
yes, indeed. since we are dealing in bulk operations, we might as well take
advantage
of that, so dropping the repeated bounds-checks inside the loops makes a lot of
sense.
no, i say here only about memory leaks. of course, unsafeRead omits bounds
checking but more
to handle the 2d indexing, i replaced readArray m (i,j) by readMatrix m (i,j):
{-# INLINE readMatrix #-}
readMatrix m ij = unsafeRead m (unsafeIndex matrixBounds ij)
matrixBounds :: ((Int,Int),(Int,Int))
matrixBounds = ((1,1),(n,n))
i'm still trying to understand why unsafeIndex
Hello Claus,
Monday, March 12, 2007, 6:03:28 PM, you wrote:
readMatrix calls index: 16s
readMatrix calls myindex: 9s
so just calling an in-module copy of the default code for index, with
bounds-check,
is almost as fast as calling unsafeIndex, and almost twice as fast as calling
Albert,
Thanks very much for your explanation. I see now that I confused the
state function with the f, but it's still not quite clear.
data MyState a b = MyStateC ([a] - ([a], b))
This defines an algebraic data type (...why is it called algebraic?)
with two type variables and a unary
On Mon, 12 Mar 2007 11:37:43 +
Neil Mitchell [EMAIL PROTECTED] wrote:
Catch also checks division by zero, explicit patterns etc. To see the
world of pain you would be in if you go down the make everything
total route, I suggest you try rewriting this program to be complete:
At Mon, 12 Mar 2007 11:24:48 +0100,
Maxime Henrion wrote:
pmaybe :: GenParser tok st a - GenParser tok st (Maybe a)
pmaybe p = option Nothing (p = return . Just)
I've been using it happily with some code of mine. Do people think
that it would be generally useful to have in Parsec?
I
Programming Languages for Mechanized Mathematics Workshop
As part of Calculemus 2007
http://www.risc.uni-linz.ac.at/about/conferences/Calculemus2007/
Hagenberg, Austria
[http://www.cas.mcmaster.ca/plmms07/]
The intent of this workshop is to examine more closely the intersection
between
On 2007-03-06, Simon Marlow [EMAIL PROTECTED] wrote:
John Goerzen wrote:
possible to create a pipe going directly from program A to program B.
You certainly can pipe directly from one process to another:
That only works for 2 processes. What if I have 4 processes, and want
to pipe from one
On Fri, Mar 09, 2007 at 10:24:14AM +, Simon Marlow wrote:
GHC doesn't have any kind of uniqueness analysis right now. It's pretty
hard to do in general: imagine a function that takes an array as an
argument and delivers an array as a result. It'll probably need two
versions: one when
On Mon, Mar 12, 2007 at 05:21:46PM -0700, John Meacham wrote:
type checker : boxy types and impredicativity paper + Wobbly type GADT
inference paper
Both of those seem to take basic Hindley-Damas-Milner as a
prerequisite ... While I've invented two closely related typechecking
algorithms, and
I'm running cygwin on WinXP and got a different failure (below) from
the
latest darcs hs-plugins. Line 11 is right after the TOP definition.
Does
anyone have a theory about what's going on here? - Conal
looks like the TOP and GHC_LIB_PATH values are the output of external
commands,
On Fri, Mar 09, 2007 at 10:58:43AM -0500, Jan-Willem Maessen wrote:
* Linear or Uniqueness types are almost what we want. I think Josef
Svenningson was the one who captured this the best: Uniqueness type
*require* that the *caller* of these routines make sure that it is
not sharing the
On 3/10/07, Robert Dockins [EMAIL PROTECTED] wrote:
I'm pretty sure you can define a catamorphism for any regular algebraic data
type. I'm not 100% sure what the story is for non-regular (AKA nested)
datatypes.
They do exist:
Initial Algebra Semantics is Enough! Patricia Johann and Neil
Tom Hawkins wrote:
I love programming in Haskell, yet even its concise expressions have
not saved my tendons from chronic RSI. Has anyone put any thought
into building an accessible Haskell development interface for those
who may not be able to use a keyboard?
One inspirational program is
Hans van Thiel wrote:
sequence :: Monad m = [m a] - m [a]
You write:
The = used by sequence is the same = in the MyState monad,
since you instantiate m to MyState String. Therefore, sequence
performs all the state transformations correctly, since = is
correct.
So the m becomes MyState String,
Dougal Stanton wrote:
The Maybe construction is very useful for explicitly handling
circumstances where the function cannot produce a sensible answer.
But how far should this notion be taken? When you're writing a function
which you realise may not produce what you want, in what circumstances
Joachim Breitner wrote:
Hi,
Am Samstag, den 10.03.2007, 14:52 -0500 schrieb Stefan Monnier:
I'm pretty sure you can define a catamorphism for any regular algebraic
data type.
Actually, so-called negative occurrences in (regular) data types cause
problems. Try to define the catamorphism of
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