Making floats not be an instance of Eq will
just cause those people to ask Why can't I compare floats for
equality?. This will lead to pretty much the same explanation.
Yes, and then all the torrent of explanation I got here about the
intricacies of floating point operations would seem more
On 2013-09-21 06:16, Mike Meyer wrote:
The single biggest gotcha is that two calculations
we expect to be equal often aren't. As a result of this, we warn
people not to do equality comparison on floats.
The Eq instance for Float violates at least one expected law of Eq:
Prelude let nan =
I think you are trying to solve a problem that doesn't exist.
* Float and Double are imprecise types by their very nature. That's exactly
what people are forgetting, and exactly what's causing misunderstandings.
Perhaps(!) it would be better to remove the option to use rational literals
as
On 21 September 2013 08:34, Stijn van Drongelen rhym...@gmail.com wrote:
* As mentioned, there is a total order (Ord) on floats (which is what you
should be using when checking whether two approximations are approximately
equal), which implies that there is also an equivalence relation (Eq).
On Sep 21, 2013 9:38 AM, Colin Adams colinpaulad...@gmail.com wrote:
On 21 September 2013 08:34, Stijn van Drongelen rhym...@gmail.com wrote:
* As mentioned, there is a total order (Ord) on floats (which is what
you should be using when checking whether two approximations are
approximately
On Sat, Sep 21, 2013 at 2:21 AM, Bardur Arantsson s...@scientician.net
wrote:
On 2013-09-21 06:16, Mike Meyer wrote:
The single biggest gotcha is that two calculations
we expect to be equal often aren't. As a result of this, we warn
people not to do equality comparison on floats.
The Eq
On Sat, Sep 21, 2013 at 10:26 AM, Mike Meyer m...@mired.org wrote:
On Sat, Sep 21, 2013 at 2:21 AM, Bardur Arantsson s...@scientician.net
wrote:
On 2013-09-21 06:16, Mike Meyer wrote:
The single biggest gotcha is that two calculations
we expect to be equal often aren't. As a result of
Hello Cafe,
I have this HTML structure:
...
table
...
tr
thCaption/th
td
a href=...Want this/a
a href=...And this/a
/td
/tr
tr
thAnother caption/th
td
tr
thYet another
Hi,
I try to develop an embedded domain specific language in Haskell.
I don't want to type ::Rational all the time, so I try to use a default
declaration for my types.
This works correctly in this simple example:
--
default (Integer, Double) -- default
Thank you very much for the work. It is deeply appreciated.
I'll test all of Keera's programs with these new versions and let you know
if something comes up.
Best regards
Ivan
On 15 September 2013 18:23, Sven Panne svenpa...@gmail.com wrote:
New versions of the OpenGL packages are available
On 2013-09-21, at 4:46 AM, Stijn van Drongelen rhym...@gmail.com wrote:
I do have to agree with Damodar Kulkarni that different laws imply different
classes. However, this will break **a lot** of existing software.
You could argue that the existing software is already broken.
If we would
Hi everybody,
I encouter some problem in my code in the following simple example: two
instances overlap for the multiplication sign `*`. The
`OverlappingInstances` extension is of no help because it seems GHC does not
look at the instance context to decide which instance is the most specific.
Hi TP,
You can add another instance to cover the case that everything is zero.
Then you don't need the :. Also it's convenient to arrange for the
a,b,c to be the argument to Tensor, as given below:
class Multiplication a b c | a b - c where
(*) :: Tensor a - Tensor b - Tensor c
instance
On Sep 21, 2013 4:17 PM, Bob Hutchison hutch-li...@recursive.ca wrote:
On 2013-09-21, at 4:46 AM, Stijn van Drongelen rhym...@gmail.com wrote:
I do have to agree with Damodar Kulkarni that different laws imply
different classes. However, this will break **a lot** of existing software.
You
Let me quibble.
* Float and Double are imprecise types by their very nature. That's exactly
what people are forgetting, and exactly what's causing misunderstandings.
Float and Double are precise types. What is imprecise is the correspondence
between finite precision floating point types
adam vogt wrote:
You can add another instance to cover the case that everything is zero.
Then you don't need the :. Also it's convenient to arrange for the
a,b,c to be the argument to Tensor, as given below:
class Multiplication a b c | a b - c where
(*) :: Tensor a - Tensor b - Tensor
On 2013-09-20 18:31, Brandon Allbery wrote:
[--snip--]
unless you have a very clever representation that can store
in terms of some operation like sin(x) or ln(x).)
I may just be hallucinating, but I think this is called describable
numbers, i.e. numbers which can described by some (finite)
On Sat, Sep 21, 2013 at 12:35 PM, Bardur Arantsson s...@scientician.netwrote:
On 2013-09-20 18:31, Brandon Allbery wrote:
[--snip--]
unless you have a very clever representation that can store
in terms of some operation like sin(x) or ln(x).)
I may just be hallucinating, but I think this
Sure. An interesting, if not terribly relevant, fact is that there are
more irrational numbers that we *can't* represent the above way than that
we can (IIRC).
However, those aren't actually interesting in solving the kinds of problems
we want to solve with a programming language, so it's
On Sat, Sep 21, 2013 at 12:43 PM, David Thomas davidleotho...@gmail.comwrote:
Sure. An interesting, if not terribly relevant, fact is that there are
more irrational numbers that we *can't* represent the above way than that
we can (IIRC).
I think that kinda follows from diagonalization... it
I think that's right, yeah.
On Sat, Sep 21, 2013 at 9:49 AM, Brandon Allbery allber...@gmail.comwrote:
On Sat, Sep 21, 2013 at 12:43 PM, David Thomas
davidleotho...@gmail.comwrote:
Sure. An interesting, if not terribly relevant, fact is that there are
more irrational numbers that we
On Sep 21, 2013 9:17 AM, Bob Hutchison hutch-li...@recursive.ca wrote:
On 2013-09-21, at 4:46 AM, Stijn van Drongelen rhym...@gmail.com wrote:
I do have to agree with Damodar Kulkarni that different laws imply
different classes. However, this will break **a lot** of existing software.
You could
On 2013-09-21 23:08, Mike Meyer wrote:
Exactly. The Eq and Ord instances aren't what's broken, at least when
you're dealing with numbers (NaNs are another story). That there are pairs
According to Haskell NaN *is* a number.
Eq and Ord are just the messengers.
No. When we declare something an
On Sat, Sep 21, 2013 at 5:28 PM, Bardur Arantsson s...@scientician.net
wrote:
On 2013-09-21 23:08, Mike Meyer wrote:
Exactly. The Eq and Ord instances aren't what's broken, at least when
you're dealing with numbers (NaNs are another story). That there are
pairs
According to Haskell NaN *is*
I've run into some strangeness with the process package. When you kill some
processes on the command line you correctly get a non-zero exit status.
However when using the process package's terminateProcess (which sends a
SIGTERM), it returns an ExitSuccess:
module Main (main) where
import
i had a longer email written out, but decided a shorter one is better.
I warmly point folks to use libs like the numbers package on hackage
http://hackage.haskell.org/packages/archive/numbers/2009.8.9/doc/html/Data-Number-BigFloat.html
it has some great alternatives to standard floats and
Hi all,
I've installed Hoogle but am having issues creating the databases. I first
did: `hoogle data all`, tried a search `hoogle [a] - a and got:
Could not find some databases: default
Searching in:
.
~/.cabal/share/hoogle-4.2.21/databases
Either the package does not exist or has not been
On Sat, Sep 21, 2013 at 11:12 PM, Michael Xavier
mich...@michaelxavier.netwrote:
I've run into some strangeness with the process package. When you kill
some processes on the command line you correctly get a non-zero exit
status. However when using the process package's terminateProcess (which
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