I've used Mathematica a lot (and, unfortunately, still using it), and written a program, which uses symbolic computations a lot to deal with simplification of multivariate polynomial systems of inequalities. Now I'm trying to get rid of that Mathematica code and rewrite the program in Haskell
I previously wrote:
The typechecker commits to the instance
and adds to the current constraints
TypeCast x Int, Ord Bool, Eq Bool
The latter two are obviously satisfied and so discharged. The former
leads to the substitution {x-Int}.
I should have been more precise and said:
Hang on, hang on, now I'm getting confused.
First you asked for the smallest (positive) x such that
1+x /= x
which is around x=4.5e15.
Then Joachim wondered if you wanted
1+x /= 1
which is around x=2.2e-16.
But not you claim to be looking for the smallest positive number that
a Double
It seems that irrefutable pattern match with existentials is safe. The
fact that irrefutable pattern match with GADT is unsafe has been
demonstrated back in September 2004.
Let us consider the following regular existential data type
data TFoo where
Foo :: Show a = a - TFoo
Bar :: Int -
Tamas K Papp writes:
Henning Thielemann wrote:
Actually, laziness allows me to formulate algorithms that look more like
the specification of the problem than the solution. E.g., I can formulate
the solution of a differential equation in terms of a power series or time
series in that way.
{-# OPTIONS -fglasgow-exts #-}
module Main where
import Data.IORef
data T a where
Li:: Int - T Int
Lb:: Bool - T Bool
La:: a - T a
writeInt:: T a - IORef a - IO ()
writeInt v ref = case v of
~(Li x) - writeIORef ref (1::Int)
readBool:: T a - IORef a - IO ()
Here is a formulation of what exactly I require from irrefutable pattern
matches for GADTs.
The problem arouse from the Optimization problem thread. In short,
here is a GADT-using, type safe version of Bertram's solution (without
balancing)
-- a binary search tree with witness about its
But that makes it refutable! For the above, either
coerce _|_ x === x
or the notation is being abused.
Making a pattern irrefutable does not mean that the function in question
will become lazy:
fromJust (~Just x) = x
fromJust _|_ === _|_
The point with coerce is that it looks very
On Sat, Sep 30, 2006 at 04:19:50AM -0400, Lennart Augustsson wrote:
Hang on, hang on, now I'm getting confused.
First you asked for the smallest (positive) x such that
1+x /= x
which is around x=4.5e15.
Then Joachim wondered if you wanted
1+x /= 1
which is around x=2.2e-16.
Oops,
Hi
[EMAIL PROTECTED] wrote:
To summarize, the main problem is to get a lazy/online algorithm (the
problem here falls into the more haste, less speed category) while
staying more type safe.
@Conor: how does this issue look like in Epigram?
Thanks for asking!
In the current Epigram
On 9/30/06, [EMAIL PROTECTED] [EMAIL PROTECTED] wrote:
data Eq a b where Refl :: Eq a a
coerce :: Eq a b - a - b
coerce ~Refl x = x
But this works well with Leibniz-style equality (
http://homepage.mac.com/pasalic/p2/papers/thesis.pdf ), because the
Equality proof/term is actually used:
Hello!
I've been trying for quite some time to find an elegant solution to
cut long strings into lines, but the only solution I was able to come
up is the following piece of ugly code.
Is there a library function for that? What kind of approach would you
suggest?
Thanks for your kind attention.
Hang on, hang on, now I'm getting confused.
First you asked for the smallest (positive) x such that
1+x /= x
which is around x=4.5e15.
Then Joachim wondered if you wanted
1+x /= 1
which is around x=2.2e-16.
But not you claim to be looking for the smallest positive number that
a Double
On 30/09/2006, at 6:15 AM, Nicolas Frisby wrote:
Software engineering is as of yet misnamed. A professional engineer's
design work should never include figuring out why the first attempt
exploded/collapsed/failed--professionals in mature engineering fields
only debug catastrophes.
That is
I've been doing it as the enclosed. I wrote it a while ago, though, and
haven't really looked too hard at it since.
-- Mark
module WordWrap (wrap) where
import Data.Maybe
options :: String - [(String, String)]
options [] = [(, )]
options (x:xs) =
let rest = map (\(ys, zs) - (x:ys, zs))
Lennart Augustsson wrote:
Hang on, hang on, now I'm getting confused.
First you asked for the smallest (positive) x such that
1+x /= x
which is around x=4.5e15.
1 + 0 /= 0
0 is smaller than 4.5e15
So I don't understand this at all...
Regards, Brian.
--
Logic empowers us and Love gives
On 30 Sep 2006, at 17:19, Brian Hulley wrote:
Lennart Augustsson wrote:
Hang on, hang on, now I'm getting confused.
First you asked for the smallest (positive) x such that
1+x /= x
which is around x=4.5e15.
1 + 0 /= 0
0 is smaller than 4.5e15
So I don't understand this at all...
But
I've done some stuff with maybe 50k rows at a time. A few bits and pieces:
1: I've used HSQL
(http://sourceforge.net/project/showfiles.php?group_id=65248) to talk to
ODBC databases. Works fine, but possibly a bit slowly. I'm not sure
where the delay is: it might just be the network I was
Thomas Davie wrote:
On 30 Sep 2006, at 17:19, Brian Hulley wrote:
Lennart Augustsson wrote:
Hang on, hang on, now I'm getting confused.
First you asked for the smallest (positive) x such that
1+x /= x
which is around x=4.5e15.
1 + 0 /= 0
0 is smaller than 4.5e15
So I don't understand
On Sat, Sep 30, 2006 at 11:54:19AM -0400, Mark T.B. Carroll wrote:
module WordWrap (wrap) where
import Data.Maybe
options :: String - [(String, String)]
options [] = [(, )]
options (x:xs) =
let rest = map (\(ys, zs) - (x:ys, zs)) (options xs)
in if x == ' ' then (, xs) :
Hello Andrea,
Saturday, September 30, 2006, 7:02:34 PM, you wrote:
-- gets the indexes of the spaces within a string
indx = findIndices (\x - if x == ' ' then True else False)
indx = findIndices (==' ')
-- takes the first index of a group of indexes
takeFirst = map (\(x:xs) - x)
takeFirst
On Sat, Sep 30, 2006 at 04:36:02PM +0100, Neil Mitchell wrote:
(if you can't be bothered to do that, the answer is lines ;)
although this wasn't the original problem, i like it, too :). but now
i am stuck in finding an optimal implementation for lines. the
following implementation is slightly
On Sat, Sep 30, 2006 at 08:56:24PM +0400, Bulat Ziganshin wrote:
i think that your algorithm is too complex. standard algorithm, imho,
is to find last space before 80 (or 75) chars margin, split here and
then repeat this procedure again. so, one line split may look like
splitAt . last .
I am trying to figure out how to use c2hs, so I wrote a wrapper for
asin from math.h:
$ cat ASin.chs
module MySin (mysin)
import C2HS
#include math.h
asin::Double - Double
asin xx =
{#call fun asin#} xx
and this is my main:
$ cat Main.hs
module Main where
import ASin
main = do
putStrLn
Hang on, hang on, now I'm getting confused.
First you asked for the smallest (positive) x such that
1+x /= x
which is around x=4.5e15.
1 + 0 /= 0
0 is smaller than 4.5e15
So I don't understand this at all...
But then 0 isn't positive.
Why not?
In any case every positive number
doh, i was just missing where after module... in my .chs file, and
some other syntax errors...
On 9/30/06, Anatoly Yakovenko [EMAIL PROTECTED] wrote:
I am trying to figure out how to use c2hs, so I wrote a wrapper for
asin from math.h:
$ cat ASin.chs
module MySin (mysin)
import C2HS
#include
On Sat, Sep 30, 2006 at 08:56:24PM +0400, Bulat Ziganshin wrote:
splitByLen len_f [] = []
splitByLen len_f xs = y : splitByLen len_f ys
where (y,ys) = splitAt (len_f xs) xs
...
so, splitByLen len_f should give you that you need, you need only to
add checks for some
Matthias Fischmann wrote:
although this wasn't the original problem, i like it, too :). but now
i am stuck in finding an optimal implementation for lines.
Isn't the obvious one good enough?
lines [] = []
lines s = go s
where
go [] = [[]]
go ('\n':s) = [] : lines s
go (c:s) = let
On Sat, Sep 30, 2006 at 08:51:40PM +0200, Udo Stenzel wrote:
To: Matthias Fischmann [EMAIL PROTECTED]
Cc: haskell-cafe@haskell.org
From: Udo Stenzel [EMAIL PROTECTED]
Date: Sat, 30 Sep 2006 20:51:40 +0200
Subject: Re: [Haskell-cafe] cutting long strings into lines
Matthias Fischmann
Bryan Burgers wrote:
Hang on, hang on, now I'm getting confused.
First you asked for the smallest (positive) x such that
1+x /= x
which is around x=4.5e15.
1 + 0 /= 0
0 is smaller than 4.5e15
So I don't understand this at all...
But then 0 isn't positive.
Why not?
In any case
Forwarded Message
From: Victor Bandur [EMAIL PROTECTED]
Reply-To: [EMAIL PROTECTED]
To: Brandon Moore [EMAIL PROTECTED]
Subject: Re: [Haskell-cafe] smallest double eps
Date: Sat, 30 Sep 2006 20:17:05 -0400
Hi all,
I'm new to this mailing list, so my response may be a little out
What a beautiful world this could be... ;-)) (*)
Cheers,
Ben
(*) Donald Fagen (forgot the name of the song)
I think I.G.Y. (International Geophysical Year) is it:
On that train all graphite and glitter
Undersea by rail
Ninety minutes from New York to Paris
(More leisure time for artists
jeff p wrote:
Hello,
So before I embark on day 1 of the project, I thought I should check and
see if anyone on this list has used Haskell to munge a ten-million-row
database table, and if there are any particular gotchas I should watch
out for.
One immediate thing to be careful about is how
Paul Johnson wrote:
I've done some stuff with maybe 50k rows at a time. A few bits and pieces:
1: I've used HSQL
(http://sourceforge.net/project/showfiles.php?group_id=65248) to talk to
ODBC databases. Works fine, but possibly a bit slowly. I'm not sure
where the delay is: it might just
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