> -- Is there a way to make this one work also?
> data Kl i o = forall s. Kl (i -> s -> (s, o))
> iso :: (i -> Kl () o) -> Kl i o
> iso f = Kl $ \i s -> (\(Kl kl) -> kl () s) (f i)
Yes, if you move the quantifier:
type Kl i o = i -> Kl1 o
data Kl1 o = forall s. Kl1 (s -> (s,o))
iso :: (i -> Kl (
Hi Haskell,
I have a question about the Haskell FFI and creating FunPtrs to
Haskell functions.
Does anyone have any recommendations for when I have a top-level
function that I would like to pass to a C function as a function
pointer (that is called via a foreign import)?
I know that the FFI prov
Welcome to issue 195 of the HWN, a newsletter covering developments in
the Haskell community. This release covers the week of August 7 to
13, 2011.
[1] http://goo.gl/8hDku
You can find a HTML rendition of this newsletter at:
http://contemplatecode.blogspot.com/2011/08/haskell-we
{-# LANGUAGE ExistentialQuantification #-}
-- Dear Cafe, this one works.
data Kl' s i o = Kl' (i -> s -> (s, o))
iso' :: (i -> Kl' s () o) -> Kl' s i o
iso' f = Kl' $ \i s -> (\(Kl' kl') -> kl' () s) (f i)
-- Is there a way to make this one work also?
data Kl i o = forall s. Kl (i -> s -> (s, o)
On Wed, Aug 17, 2011 at 9:11 AM, Rogan Creswick wrote:
> On Wed, Aug 17, 2011 at 6:29 AM, Gang wrote:
>>
>> sorry to bother
>>
>
> Not in the least!
>
> I was trying to figure out what problem you were encountering, and I
> learned a lot. I never did recreate your problem, but in the process
> I
On Wed, Aug 17, 2011 at 12:27 PM, Ryan Newton wrote:
> The more fundamental problem is that splitting is neither well understood
>> nor generally safe, and as such it should not be in the basic Random class.
>>
>
> Would you mind elaborating?
>
Certainly. The purpose of splitting a PRNG is to cr
>
> The more fundamental problem is that splitting is neither well understood
> nor generally safe, and as such it should not be in the basic Random class.
>
Would you mind elaborating? Splitting was not well-understood by the
original authors of System.Random; that much is in the comments. Nor
Ccing cabal-dev.
On Aug 17, 2011 9:12 AM, "Rogan Creswick" wrote:
>
> On Wed, Aug 17, 2011 at 6:29 AM, Gang wrote:
> >
> > sorry to bother
> >
>
> Not in the least!
>
> I was trying to figure out what problem you were encountering, and I
> learned a lot. I never did recreate your problem, but i
On 11-08-17 12:10 PM, Patrick Browne wrote:
-- Are + and negate part of the signature of Numb1?
class Numb0 a => Numb1 a where
No.
-- Is it possible to override these operations in instances of Numb1?
-- Something like:
-- instance Numb1 Float where
--x + y = y
--negate x = x
No
On Wed, Aug 17, 2011 at 11:10 AM, Ryan Newton wrote:
> The problem with Mersenne twister is that it doesn't split well. The main
> reason for crypto prng in this package would not be to advertise to people
> that "System.Random can be used for security-related apps" *but to make
> splitting reas
The problem with Mersenne twister is that it doesn't split well. The main
reason for crypto prng in this package would not be to advertise to people
that "System.Random can be used for security-related apps" *but to make
splitting reasonably safe*. It's not good enough to have a known-bad
generat
I'm trying to do the following from Chapter 5 of "Real World Haskell":
Our choice of naming for the source file and function is deliberate. To
create an executable, *ghc* expects a module named Main that contains a
function named main. The main function is the one that will be called when
we run t
I'm not sure I understand the comments there. Does this solve the
issue for GHC 7.2 only, or for 7.* as well? Yesod is still officially
supporting 6.12 and 7.0.
On Wed, Aug 17, 2011 at 11:17 AM, Bas van Dijk wrote:
> On 17 August 2011 07:16, Michael Snoyman wrote:
>> There's a bug in GHC that pr
On Wed, Aug 17, 2011 at 8:56 AM, Ryan Newton wrote:
>
> I'm the maintainer of random. If people could decide on what the
> alternative name would be we could put it through the library proposal
> process. It seems that one problem at this moment is the lack of a single,
> clear "right" answer.
Ryan Newton wrote:
> I'm the maintainer of random. If people could decide on what the
> alternative name would be we could put it through the library proposal
> process. It seems that one problem at this moment is the lack of a
> single, clear "right" answer. Replacing one debatable not-quite-
Hi,
Below are two questions concerning overloading in a sub-class.
Thanks,
Pat
class Numb0 a where
(+) :: a -> a -> a
negate :: a -> a
instance Numb0 Int where
x + y = y
negate x = x
-- Are + and negate part of the signature of Numb1?
class Numb0 a => Numb1 a where
-- Is it possible to
Hi all,
I'm the maintainer of random. If people could decide on what the
alternative name would be we could put it through the library proposal
process. It seems that one problem at this moment is the lack of a single,
clear "right" answer. Replacing one debatable not-quite-right choice with
an
Thank you for your reply.
On Aug 17, 7:48 pm, Ryan Yates wrote:
> I had to stare at this for a while to see the difference. In the C++
> version the comparison's in loop B and loop C are always between areas
> of triangles that are off by one in a single index. In the haskell
> calArea though,
Hi,
I'll be heading to ICFP in September, and I'm hoping to find someone to
share a room with to save on hotel costs. Are there any other students
looking for a roommate?
Cheers,
Dan
___
Haskell-Cafe mailing list
Haskell-Cafe@haskell.org
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I had to stare at this for a while to see the difference. In the C++
version the comparison's in loop B and loop C are always between areas
of triangles that are off by one in a single index. In the haskell
calArea though, comparisons are between the passed area and triangles
off by one from the
On Wed, Aug 17, 2011 at 6:29 AM, Gang wrote:
>
> sorry to bother
>
Not in the least!
I was trying to figure out what problem you were encountering, and I
learned a lot. I never did recreate your problem, but in the process
I ran into a whole host of other annoyances and strange situations
relat
Solved.
Under my ghc6.12.3 environment, I manually downloaded and installed the
encoding-0.6.3 package together with mtl-1.1.0.2, and pin HaXml to 1.19 ,
Modify the dependence rules of
mtl to mtl <2
HaXml>=1.19 to HaXml=1.19
Then
runhaskell Setup configure --flags=splitBase --flags=newGHC --u
Hello all
I am trying implement this algorithm [
http://stackoverflow.com/questions/1621364/how-to-find-largest-triangle-in-convex-hull-aside-from-brute-force-search
] in Haskell but i am getting wrong answer for some test cases. A c++
implementation which is accepted for this problem [
http://ww
hi, cafe:
I go through to the encoding package installation problem again.
cabal install encoding
Resolving dependencies...
/tmp/encoding-0.6.68093/encoding-0.6.6/dist/setup/setup: 4: Syntax error:
";" unexpected
when I have a check on the this issue, I get:
file ~/.cabal/packages/
hackage
Brandon Allbery wrote:
> > > I've noticed there's a convention to put modules having to deal
> > > with randomness into System.Random. I thought System was for OS
> > > interaction? Granted getting a random seed usually means going to
> > > the OS, but isn't the rest of it, like generating rand
On 17 August 2011 07:16, Michael Snoyman wrote:
> There's a bug in GHC that prevents C++ code from working correctly with
> Template Haskell
For reference this is the bug Michael is talking about:
http://hackage.haskell.org/trac/ghc/ticket/5289
As explained by Sebastian and the ticket, to work
On Wed, Aug 17, 2011 at 00:31, Sebastian Fischer wrote:
> Additionally, I linked /usr/lib/libstdc++.so.6 to /usr/lib/libstdc++.so
>> before I could successfully install tkyprof. Not sure about the
>> consequences..
>
>
This means you didn't install your distribution's libstdc++-dev (or whatever
i
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