On Feb 11, 2008 10:18 PM, Uwe Hollerbach <[EMAIL PROTECTED]> wrote:
> If I fire up ghci, import
> Data.Ratio and GHC.Real, and then ask about the type of "infinity", it
> tells me Rational, which as far as I can tell is Ratio Integer...?
Yes, Rational is Ratio Integer. It might not be a good idea
Ratio Integer may possibly have the same trouble, or maybe something
related. I was messing around with various operators on Rationals and
found that positive and negative infinity don't compare right. Here's
a small program which shows this; if I'm doing something wrong, I'd
most appreciate it bei
Hello Haskellers,
After a few years hiatus, I'm pleased to announce that the Melbourne
Functional Programming Union
(FPU) is back.
What is the FPU? It is a group of people who are interested in all
things functional programming.
We hold regular informal talks, and have friendly discussions
On Mon, 2008-02-11 at 13:34 -0800, Stefan O'Rear wrote:
> On Mon, Feb 11, 2008 at 01:59:09PM +, Neil Mitchell wrote:
> > Hi
> >
> > > > (x >>= f) >>= g == x >>= (\v -> f v >>= g)
> > >
> > > Or stated another way:
> > >
> > > (x >>= f) >>= g == x >>= (f >>= g)
> >
> > Which is totally wrong,
Richard A. O'Keefe comments:
[floating point addition is not associative]]
And this is an excellent example of why violating expected laws is BAD.
The failure of floating point addition to be associative means that there
are umpteen ways of computing polynomials, for example, and doing it
2008/2/11 Galchin Vasili <[EMAIL PROTECTED]>:
> http://hackage.haskell.org/packages/archive/pkg-list.html .. what are
> some packages that use Storable?
binary and binary-strict at least.
AGL
--
Adam Langley [EMAIL PROTECTED]
http://www.imperialviolet.
On 12 Feb 2008, at 10:35 am, David Benbennick wrote:
Some months ago I pointed out that Ratio Int (which is an Ord
instance) doesn't satisfy this property. I provided a patch to fix
the problem, but my bug report was closed as wontfix:
http://hackage.haskell.org/trac/ghc/ticket/1517.
I'm not h
On 12 Feb 2008, at 4:35 am, Andrew Butterfield wrote:
[floating point addition is not associative]
And this is an excellent example of why violating expected laws is BAD.
The failure of floating point addition to be associative means that
there
are umpteen ways of computing polynomials, for exa
ok:
> On the subject of data types, I've recently seen Haskell code using
> data Foo ... = Foo { ... }
> where I would have used newtype instead of data. When is it a good
> idea to avoid newtype?
It depends what's in the ...
If its just something with the same representation as an existin
On the subject of data types, I've recently seen Haskell code using
data Foo ... = Foo { ... }
where I would have used newtype instead of data. When is it a good
idea to avoid newtype?
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Dan Piponi wrote:
> IOn Feb 11, 2008 9:46 AM, Miguel Mitrofanov <[EMAIL PROTECTED]> wrote:
>> It's well known that "ListT m" monad violates this law in general
>> (though it satisfies it for some particular monads m). For example,
>
> I went through this example in quite a bit of detail a while ag
Hm, there used to be an experimental search tool that could find
packages by which packages they depended on. I can't find it,
though, so I assume it has been removed in the meantime.
On 11 feb 2008, at 22.28, Galchin Vasili wrote:
Hello,
http://hackage.haskell.org/packages/archive/p
On Mon, Feb 11, 2008 at 5:05 PM, Don Stewart <[EMAIL PROTECTED]> wrote:
> Have you thought about uploading it to hackage.haskell.org?
> We've got some similar stuff up there already,
>
> http://hackage.haskell.org/cgi-bin/hackage-scripts/package/sat-1.1.1
>
> so feel free to upload this code
dbueno:
> Hi all,
>
> I've recently done a small Haskell port of some OCaml code from a
> paper entitled "SAT-MICRO: petit mais costaud!" It's a tiny (one
> emacs buffer for the algorithm, ~160 lines overall) DPLL SAT solver
> with non-chronological backtracking, implemented using the Cont monad
Hi all,
I've recently done a small Haskell port of some OCaml code from a
paper entitled "SAT-MICRO: petit mais costaud!" It's a tiny (one
emacs buffer for the algorithm, ~160 lines overall) DPLL SAT solver
with non-chronological backtracking, implemented using the Cont monad
and callCC. If anyo
Hi,
I'm writing a simple parser for a line-oriented language using Parsec. A
group of lines is parsed by a parser that tokens are of type String.
Each token is again parsed by a parser that tokens are of type Char
(i.e. this parser has the Parsec type Parser a).
Now I wrote a transforming fu
On Feb 11, 2008 11:24 AM, Wolfgang Jeltsch <[EMAIL PROTECTED]> wrote:
> a < b && b < c => a < c
>
> If an Ord instances doesn't obey these laws than it's likely to make Set and
> Map behave strangely.
Some months ago I pointed out that Ratio Int (which is an Ord
instance) doesn't satisfy this
On Mon, Feb 11, 2008 at 01:59:09PM +, Neil Mitchell wrote:
> Hi
>
> > > (x >>= f) >>= g == x >>= (\v -> f v >>= g)
> >
> > Or stated another way:
> >
> > (x >>= f) >>= g == x >>= (f >>= g)
>
> Which is totally wrong, woops.
>
> See this page for lots of details about the Monad Laws and quite
hitesh.jasani:
> nano-hmac provides bindings to OpenSSL's HMAC interface. With this release
> the
> set of hashing functions supported is: MD5, SHA, SHA1, SHA224, SHA256, SHA384,
> SHA512.
>
> If you're unfamiliar with HMAC's then you may want to check out the second
> link
> below where I expl
Hello,
http://hackage.haskell.org/packages/archive/pkg-list.html .. what are
some packages that use Storable?
Regards, Vasili
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Alfonso Acosta wrote:
So type-level + parametrized-data is my vote. But don't let's spend too much
time discussing the name. ;-)
Fair enough. type-level + parameterized-data it is then (unless
someone else has a better suggestion). I'm going to begin coding now.
hang on, "parametrized" or "p
Of course the most *general* way requires an Eq constraint:
> List.nub :: Eq a => [a] -> [a]
But there are better functions (already mentioned) with the less general
Ord constraint.
Int and String are instances of Ord. "some other user defined data type"
probably is too, but if you mean "an
Am Montag, 11. Februar 2008 16:35 schrieb Andrew Butterfield:
> This is precisely Jerzy's point - you can have many mathematical laws as
> you like but there is no guarantee that a programming languages
> implementation will satisfy them.
But people writing instances of type classes should take ca
Am Montag, 11. Februar 2008 14:57 schrieb Michael Reid:
> > Now it should be easier to see that this is simply associativity. It's
> > easy enough to violate, if you want to - but I don't have any nice
> > simple examples to hand.
>
> I have recently been reading a tutorial or paper where a Monad t
Am Montag, 11. Februar 2008 18:17 schrieben Sie:
> […]
> As suggested by the pointer you provided, I redefined FSVec and tailV
> using a transformating of Succ into a type synonym family (see the end
> of this mail for its full definition) but it didn't help.
Be careful! Type family support is s
Hi Dan,
On Feb 10, 2008 6:08 PM, Dan Licata <[EMAIL PROTECTED]> wrote:
> > > The ideal type for the function would be:
> > >
> > > vector :: [a] -> FSVec s a
Well, I probably didn't express myself properly when writing "The
ideal type", "the first type which comes to mind" would have been more
ac
IOn Feb 11, 2008 9:46 AM, Miguel Mitrofanov <[EMAIL PROTECTED]> wrote:
> It's well known that "ListT m" monad violates this law in general
> (though it satisfies it for some particular monads m). For example,
I went through this example in quite a bit of detail a while ago and
wrote it up here:
ht
On 2008.02.11 09:42:44 -0800, Adam Langley <[EMAIL PROTECTED]> scribbled 0.5K
characters:
> On Feb 11, 2008 12:54 AM, Hitesh Jasani <[EMAIL PROTECTED]> wrote:
> > nano-hmac provides bindings to OpenSSL's HMAC interface. With this release
> > the
> > set of hashing functions supported is: MD5, SH
Thanks, guys! It looks at first glance as if the code Thorkil posted is
similar to mine (grow comparison number in steps of 2 in the exponent, then
binary-search to get the exact exponent), while Stefan's version is more
similar to the walk-the-list idea I had in mind. I'll play with both of
these
(x >>= f) >>= g == x >>= (\v -> f v >>= g)
However, this seems to me a kind of mathematical identity. If it is
mathematical identity, a programmer need not care about this law to
implement a monad. Can anyone give me an example implementation of
monad that violate this law ?
It's well known tha
On Feb 9, 2008 2:12 AM, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote:
> I'd like to build a database model with winHugs that allows
> a "recursive relation". For example a single instance of
> entity "components" is related with at least another row of
> the entity "components" (1 to many relationsh
On Feb 11, 2008 12:54 AM, Hitesh Jasani <[EMAIL PROTECTED]> wrote:
> nano-hmac provides bindings to OpenSSL's HMAC interface. With this release
> the
> set of hashing functions supported is: MD5, SHA, SHA1, SHA224, SHA256, SHA384,
> SHA512.
Just a heads up; PHO has written nice bindings to much
Hi Wolfgang,
On Feb 10, 2008 5:43 PM, Wolfgang Jeltsch <[EMAIL PROTECTED]> wrote:
I added some line annotations to the code below so that errors can be
more easily understood
> > (<+>) :: Add s1 s2 s3 => FSVec s1 a -> FSVec s2 a -> FSVec s3 a -- line 78
> > NullV <+> ys = ys -- line 79
> > (x
On 11 Feb 2008, at 7:52 AM, Arnar Birgisson wrote:
Hi all,
On Feb 11, 2008 3:14 PM, apfelmus <[EMAIL PROTECTED]> wrote:
I will be mean by asking the following counter question:
x + (y + z) = (x + y) + z
is a mathematical identity. If it is a mathematical identity, a
programmer need not ca
Andrew Butterfield wrote:
let m denote the "list monad" (hypothetically). Let's instantiate:
return :: x -> [x]
return x = [x,x]
(>>=) :: [x] -> (x -> [y]) -> [y]
xs >>= f = concat ((map f) xs)
Let g n = [show n]
Here (return 1 >>= g ) [1,2,3] = ["1","1","1","1","1","1"]
but g[1,2,3] = [
Hi all,
On Feb 11, 2008 3:14 PM, apfelmus <[EMAIL PROTECTED]> wrote:
> I will be mean by asking the following counter question:
>
>x + (y + z) = (x + y) + z
>
> is a mathematical identity. If it is a mathematical identity, a
> programmer need not care about this law to implement addition + . C
On Feb 11, 2008 1:35 PM, Andrew Butterfield
<[EMAIL PROTECTED]> wrote:
> Hugs> 1.0 + (2.5e-15 + 2.5e-15)
> 1.01 :: Double
> Hugs> (1.0 + 2.5e-15) + 2.5e-15
> 1.0 :: Double
Prelude> (1e30 + (-1e30)) + 1
1.0
Prelude> 1e30 + ((-1e30) + 1)
0.0
I love this example from David Goldberg
(http
apfelmus wrote:
Deokjae Lee wrote:
Tutorials about monad mention the "monad axioms" or "monad laws". The
tutorial "All About Monads" says that "It is up to the programmer to
ensure that any Monad instance he creates satisfies the monad laws".
The following is one of the laws.
(x >>= f) >>= g =
On 11 Feb 2008, at 5:33 AM, Deokjae Lee wrote:
Tutorials about monad mention the "monad axioms" or "monad laws". The
tutorial "All About Monads" says that "It is up to the programmer to
ensure that any Monad instance he creates satisfies the monad laws".
The following is one of the laws.
(x >>
Deokjae Lee wrote:
Tutorials about monad mention the "monad axioms" or "monad laws". The
tutorial "All About Monads" says that "It is up to the programmer to
ensure that any Monad instance he creates satisfies the monad laws".
The following is one of the laws.
(x >>= f) >>= g == x >>= (\v -> f
Hallo!
I have this code:
q1 :: EName -> [ApprenticeInfo]
q1 c = [apprenticeInfo n | n <- allApprentices, member ((sq4
c) (firstOf5(n))) == True]
sq4 :: ESurname -> [IDB]
sq4 c = (sq3 (sq1 (c)))
firstOf5 :: (a,b,c,d,e) -> a
firstOf5 (n,_,_,_,_) = n
member
On Mon, 11 Feb 2008, [EMAIL PROTECTED] wrote:
> Hallo!
>
> I have this code:
>
> q1 :: EName -> [ApprenticeInfo]
> q1 c = [apprenticeInfo n | n <- allApprentices, member ((sq4
> c) (firstOf5(n))) == True]
>
> sq4 :: ESurname -> [IDB]
> sq4 c = (sq3 (sq1 (c
On Feb 11, 2008 2:27 PM, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote:
> Hallo!
>
> I have this code:
>
> q1 :: EName -> [ApprenticeInfo]
> q1 c = [apprenticeInfo n | n <- allApprentices, member ((sq4
> c) (firstOf5(n))) == True]
>
> sq4 :: ESurname -> [IDB]
Deokjae Lee cites:
The tutorial "All About Monads" says that "It is up to the programmer to
ensure that any Monad instance he creates satisfies the monad laws".
The following is one of the laws.
(x >>= f) >>= g == x >>= (\v -> f v >>= g)
However, this seems to me a kind of mathematical id
Hi
> > (x >>= f) >>= g == x >>= (\v -> f v >>= g)
>
> Or stated another way:
>
> (x >>= f) >>= g == x >>= (f >>= g)
Which is totally wrong, woops.
See this page for lots of details about the Monad Laws and quite a
nice explanation of where you use them:
http://www.haskell.org/haskellwiki/Monad_L
> Now it should be easier to see that this is simply associativity. It's
> easy enough to violate, if you want to - but I don't have any nice
> simple examples to hand.
>
>
I have recently been reading a tutorial or paper where a Monad that violated
this law was presented. The authors shrugged it o
On Mon, Feb 11, 2008 at 02:24:19PM +0100, Wolfgang Jeltsch wrote:
> Am Montag, 11. Februar 2008 02:09 schrieb Don Stewart:
> > [???]
>
> > * Imlib 0.1.1. Uploaded by Cale Gibbard. [120]Imlib: Added by
> >CaleGibbard, Sun Jan 13 22:26:59 PST 2008..
>
> > [???]
>
> > * haddock 2.
Hi
> The following is one of the laws.
>
> (x >>= f) >>= g == x >>= (\v -> f v >>= g)
Or stated another way:
(x >>= f) >>= g == x >>= (f >>= g)
Now it should be easier to see that this is simply associativity. It's
easy enough to violate, if you want to - but I don't have any nice
simple exampl
Tutorials about monad mention the "monad axioms" or "monad laws". The
tutorial "All About Monads" says that "It is up to the programmer to
ensure that any Monad instance he creates satisfies the monad laws".
The following is one of the laws.
(x >>= f) >>= g == x >>= (\v -> f v >>= g)
However, th
Am Montag, 11. Februar 2008 02:09 schrieb Don Stewart:
> […]
> * Imlib 0.1.1. Uploaded by Cale Gibbard. [120]Imlib: Added by
>CaleGibbard, Sun Jan 13 22:26:59 PST 2008..
> […]
> * haddock 2.0.0.0. Uploaded by David Waern. [147]haddock: Added by
>DavidWaern
> […]
What'
On Feb 11, 2008 7:53 AM, Felipe Lessa <[EMAIL PROTECTED]> wrote:
> read that IORef and do a big tell to the outside Writer monad. I'd say
> that this is a safe use of unsafePerformIO as it shouldn't break
> referential transparency. But without this hack I don't think we could
Well, not really as
On Feb 10, 2008 9:52 PM, Thomas Hartman <[EMAIL PROTECTED]> wrote:
> So, I would say this proves my main point, which was that you could
> accomplish the same thing using the writer monad that you could do
> using the more "ad hoc" trace function from Debug.Trace.
Not really. That only happens wit
2008/2/11, Peter Verswyvelen <[EMAIL PROTECTED]>:
>
> Yes, sorry, GHC's strictness analyzer.
>
> What I meant with this email is that I guess that for a strictness analyzer,
> the information that a function is strict in an argument *independent from
> the other arguments* would not be good enough
nano-hmac provides bindings to OpenSSL's HMAC interface. With this release the
set of hashing functions supported is: MD5, SHA, SHA1, SHA224, SHA256, SHA384,
SHA512.
If you're unfamiliar with HMAC's then you may want to check out the second link
below where I explain a little bit about them in a
Yes, sorry, GHC's strictness analyzer.
What I meant with this email is that I guess that for a strictness analyzer,
the information that a function is strict in an argument *independent from
the other arguments* would not be good enough in itself for optimization, it
would be better to also us
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