On Thu, Nov 04, 2004 at 08:32:52PM +0100, Sven Panne wrote:
It's an old thread, but nothing has really happened yet, so I'd like to
restate and expand the question: What should the behaviour of toRational,
fromRational, and decodeFloat for NaN and +/-Infinity be? Even if the report
is unclear
I would be very careful of adding non-rationals to the Rational type.
Why is there no Irrational class. This would make more sense for
Floats and Doubles than the fraction based Rational class. We could
also add an implementation of infinite precision irrationals using
a
pair of Integers for
My guess is because irrationals can't be represented on a discrete
computer (unless you consider a computaion, the limit of which is the
irrational number in question). A single irrational might not just be
arbitrarily long, but it may have an _infinite_ length representation!
What you have
On Fri, 5 Nov 2004, Robert Dockins wrote:
What IEEE has done is shoehorned in some values that aren't really
numbers into their representation (NaN certainly; one could make a
convincing argument that +Inf and -Inf aren't numbers).
I wonder why Infinity has a sign in IEEE floating
Hello Experts,
I need MVar and Chan to be instances of Typeable. Any hint on how this is most
easily done would be greatly appreciated. I could change the libraries and
add 'deriving Typeable' but I hesitate to do so.
Cheers,
Ben
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Henning Thielemann wrote:
I wonder why Infinity has a sign in IEEE floating processing, as well as
0. To support this behaviour uniformly one would need a +0 or -0 offset
for each number, which would lead straightforward to non-standard analysis
...
See Branch Cuts for Complex Elementary
On Friday 05 November 2004 14:57, Henning Thielemann wrote:
On Fri, 5 Nov 2004, Robert Dockins wrote:
I wonder why Infinity has a sign in IEEE floating processing, as well as
0.
As regards Inf, this makes sense, because with +Inf and -Inf order is
preserved. With one unsigned Inf nothing is
On Fri, Nov 05, 2004 at 01:57:53PM +0100, Benjamin Franksen wrote:
Hello Experts,
I need MVar and Chan to be instances of Typeable. Any hint on how this is most
easily done would be greatly appreciated. I could change the libraries and
add 'deriving Typeable' but I hesitate to do so.
The
My guess is because irrationals can't be represented on a discrete computer
Well, call it arbitrary precision floating point then. Having built in
Integer support, it does seem odd only having Float/Double/Rational...
Keean.
..
___
On Fri, 2004-11-05 at 13:57, Henning Thielemann wrote:
On Fri, 5 Nov 2004, Robert Dockins wrote:
What IEEE has done is shoehorned in some values that aren't really
numbers into their representation (NaN certainly; one could make a
convincing argument that +Inf and -Inf aren't numbers).
On Friday 05 November 2004 14:11, you wrote:
It's worse: Since according to IEEE +0 is not equal to -0, atan2 is not a
function!
Sorry, I meant to write: Since according to IEEE +0 *is* to be regarded as
equal to -0, atan2 is not a function. (Because it gives different values for
argument
On Friday 05 November 2004 15:51, you wrote:
On Fri, Nov 05, 2004 at 01:57:53PM +0100, Benjamin Franksen wrote:
Hello Experts,
I need MVar and Chan to be instances of Typeable. Any hint on how this is
most easily done would be greatly appreciated. I could change the
libraries and add
nstance Typeable a = Typeable (MVar a) where
typeOf (x::x) =
mkAppTy (mkTyCon Control.Concurrent.MVar.MVar) [typeOf (undefined::x)]
Keean.
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[...] Thus (a-b) is not the same as -(b-a) for IEEE floats!
Nor is x*0 equal to 0 for every x; nor does x == y imply f(x) == f(y)
for every x, y, f; nor is addition or multiplication associative. There
aren't many identities that do hold of floating point numbers.
Yes, but they DO hold for
Benjamin Franksen [EMAIL PROTECTED] writes:
It's worse: Since according to IEEE +0 is not equal to -0, atan2 is not a
function!
Sorry, I meant to write: Since according to IEEE +0 *is* to be regarded as
equal to -0, atan2 is not a function. (Because it gives different values for
argument
On Friday 05 November 2004 16:20, MR K P SCHUPKE wrote:
nstance Typeable a = Typeable (MVar a) where
typeOf (x::x) =
mkAppTy (mkTyCon Control.Concurrent.MVar.MVar) [typeOf
(undefined::x)]
I may be missing something but this look like an open recursion to me. The
type 'x' is 'MVar a',
On Friday 05 November 2004 13:57, Benjamin Franksen wrote:
Hello Experts,
I need MVar and Chan to be instances of Typeable. Any hint on how this is
most easily done would be greatly appreciated. I could change the libraries
and add 'deriving Typeable' but I hesitate to do so.
Ok, I found a
On Fri, 5 Nov 2004 14:43:55 +0100
Benjamin Franksen [EMAIL PROTECTED] wrote:
snip
the instances by hand. My first attempt was:
instance Typeable a = Typeable (MVar a) where
typeOf x =
mkAppTy (mkTyCon Control.Concurrent.MVar.MVar) [typeOf (undefined::a)]
but unfortunately this
My mistake:
instance Typeable a = Typeable (MVar a) where
typeOf (x::MVar x) =
mkAppTy (mkTyCon Control.Concurrent.MVar.MVar) [typeOf (undefined::x)]
Keean.
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On Friday 05 November 2004 15:07, Benjamin Franksen wrote:
instance Typeable a = Typeable (MVar a) where
typeOf x =
mkAppTy (mkTyCon Control.Concurrent.MVar.MVar) [typeOf y]
where
y = unsafePerformIO $ do
z - newEmptyMVar = readMVar
return (z `asTypeOf` x)
I'm experimenting with a Literate Haskell style to construct a tutorial
about Description Logics [1][2].
I'm developing the material in small sections, and using examples in the
document to test the code as I go along . I therefore find that I want to
introduce the components of class and
On Fri, Nov 05, 2004 at 02:53:01PM +, MR K P SCHUPKE wrote:
My guess is because irrationals can't be represented on a discrete computer
Well, call it arbitrary precision floating point then. Having built in
Integer support, it does seem odd only having Float/Double/Rational...
There are
Hi all -
I'm a first-timer here, and am *very* much attracted by Haskell's elegance
and power ... :-)
I have only poked around briefly with Haskell so far (at the hello world
level). One thing that I have come across, and which really got me thinking,
was the page on the Haskell
On Fri, Nov 05, 2004 at 01:57:53PM +0100, Benjamin Franksen wrote:
Hello Experts,
I need MVar and Chan to be instances of Typeable. Any hint on how this is most
easily done would be greatly appreciated. I could change the libraries and
add 'deriving Typeable' but I hesitate to do so.
Hi again -
Apologies for another post from me so soon (and for replying to my own
post).
Regarding my post about arrows and Haskell (and the idea of trying to
define Haskell's grammar in terms of arrows) - upon thinking about that, I'm
pretty much of the opinion that it'd be an
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