Henning Thielemann wrote:
On Mon, 16 Feb 2009, Louis Wasserman wrote:
Overnight I had the following thought, which I think could work
rather well. The most basic implementation of the idea is as
follows:
class MonadST s m | m - s where
liftST :: ST s a - m a
instance MonadST s (ST
On Thu, Feb 19, 2009 at 3:50 AM, Thomas DuBuisson
thomas.dubuis...@gmail.com wrote:
I recall that Niel made sure hoogle doesn't search through
non-portable libraries (a shame), but I thought Network.Socket could
be used on Windows and yet Hoogle does not give any results for
'socket' or any
Am Donnerstag, 19. Februar 2009 02:22 schrieb sylvain:
Haskell is a nice, mature and efficient programming language.
By its very nature it could also become a nice executable formal
specification language, provided there is tool support.
Wouldn’t it be better to achieve the goals you describe
Am Donnerstag, 19. Februar 2009 00:17 schrieben Sie:
On Tue, 17 Feb 2009, Wolfgang Jeltsch wrote:
Now, a package only for one class with one method seems like overkill.
However, it could serve as a start for a package of all kinds of
algebraic structures. So I called the package “algebra”
Am Donnerstag, 19. Februar 2009 05:10 schrieben Sie:
Wolfgang Jeltsch wrote:
I’ve put myself as a potential mentor on the old Haskell SoC ticket
(http://hackage.haskell.org/trac/summer-of-code/ticket/17). However,
one or two years ago I was told that mentoring is a very time-consuming
Ketil == Ketil Malde ke...@malde.org writes:
Ketil gregg reynolds d...@mobileink.com writes:
I.e. war, plague.famine. etc.
Ketil No, those are quite outdated by now. The new horsemen of
Ketil the programming apocalypse are, of course, IO,
Ketil MutableState,
The Network.Socket module works fine on Windows. The original Winsock
implementation was based on the Berkeley sockets api.
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2009/2/19 Wolfgang Jeltsch g9ks1...@acme.softbase.org
Am Donnerstag, 19. Februar 2009 02:22 schrieb sylvain:
Haskell is a nice, mature and efficient programming language.
By its very nature it could also become a nice executable formal
specification language, provided there is tool
Greetings,
Is there a typeclass for mappings with a Data.Map-like interface, with
stuff like: empty, insert, insertWithKey, unionWith etc. ?
And, probably, a similar typeclass for mutable mappings like Data.Hashtable.
Looks like such a thing would be useful; as for now, I see at least
two
Ketil Malde wrote:
Rick R writes:
I'm sure Premier Election Solutions (formerly Diebold) can provide us with
an online voting solution.
You know, while the recent voting scandals have been milked for all
they're worth by the open source community, FP has been very quiet
about it.
I
This could look like:
module Integer where
..
theorem read_parses_what_show_shows :
(a :: Integer, Show a, Read a) =
show . read a = id a
proof
axiom
There are several problems with this approach.
For example, I can show:
const 0 (head []) = 0
But if I pretend that I don't
Unless Google's changed things, the organization gets 500$ for each
project. What the Darcs organization does with that, who knows.
Yes, who knows. The Haskell organization didn't give a cent
to the mentors, as far as I know. Am I wrong here?
That is correct. The haskell.org mentors
Bulat Ziganshin wrote:
Hello Khudyakov,
Saturday, February 7, 2009, 4:01:57 PM, you wrote:
How do you plan to handle filenames? Currently FilePath is simply a string.
i think that this patch does nothing to unicode filenames support
Correct - I'm aware that there's a problem with
Jonathan Cast-2 wrote:
Summary: Existential types are not enough for ST. You need the rank 2
type, to guarantee that *each* application of runST may (potentially)
work with a different class of references. (A different state thread).
Interesting.
What's going on in the example that
Hello Simon,
Thursday, February 19, 2009, 3:21:03 PM, you wrote:
Correct - I'm aware that there's a problem with filenames, but it hasn't
been tackled yet. There probably isn't anything sensible that we can do
without changing FilePath into an ADT.
i think that FilePath=String is ok, we
On Thursday 19 February 2009 7:22:48 am Kim-Ee Yeoh wrote:
Jonathan Cast-2 wrote:
Summary: Existential types are not enough for ST. You need the rank 2
type, to guarantee that *each* application of runST may (potentially)
work with a different class of references. (A different state
Am Donnerstag, 19. Februar 2009 11:35 schrieb Alberto G. Corona:
2009/2/19 Wolfgang Jeltsch g9ks1...@acme.softbase.org
Am Donnerstag, 19. Februar 2009 02:22 schrieb sylvain:
Haskell is a nice, mature and efficient programming language.
By its very nature it could also become a nice
On Thu, Feb 19, 2009 at 9:51 PM, Eugene Kirpichov ekirpic...@gmail.com wrote:
Greetings,
Is there a typeclass for mappings with a Data.Map-like interface, with
stuff like: empty, insert, insertWithKey, unionWith etc. ?
And, probably, a similar typeclass for mutable mappings like
Unfortunately the proofs in dependently typed languages are
extremely long and tedious to write. Some kind of compiler proofing
tool could ease the pain, but I do not think it has low enough
complexity for a GSoC project.
Regards,
John A. De Goes
N-BRAIN, Inc.
The Evolution of
Yes, this is indeed the point. Right now we express properties that a
type class should obey, but there is no compiler assistance to prove
or verify them.
A compiler aware of properties can do additional symbolic
manipulation to increase performance. Surely there has been some
research
There's a lot to chew on (thank you!), but I'll just take something
I can handle for now.
Dan Doel wrote:
An existential:
exists a:T. P(a)
is a pair of some a with type T and a proof that a satisfies P (which has
type
P(a)). In Haskell, T is some kind, and P(a) is some type
On Thu, Feb 19, 2009 at 2:46 PM, Mark Wotton mwot...@gmail.com wrote:
On Thu, Feb 19, 2009 at 9:51 PM, Eugene Kirpichov ekirpic...@gmail.com
wrote:
Greetings,
Is there a typeclass for mappings with a Data.Map-like interface, with
stuff like: empty, insert, insertWithKey, unionWith etc. ?
Hello,
While browsing documentation I've found following function
-- | @'fix' f@ is the least fixed point of the function @f@,
-- i.e. the least defined @x@ such that @f x = x...@.
fix :: (a - a) - a
fix f = let x = f x in x
I have two questions. How could this function be used? I'm unable
On Thu, 2009-02-19 at 17:00 +0300, Khudyakov Alexey wrote:
Hello,
While browsing documentation I've found following function
-- | @'fix' f@ is the least fixed point of the function @f@,
-- i.e. the least defined @x@ such that @f x = x...@.
fix :: (a - a) - a
fix f = let x = f x in x
On Feb 14, 2009, at 2:29 PM, Luke Palmer wrote:
To me, typeclasses are at their best when you have a real
abstraction to encode.
I agree.
If you are having trouble using a typeclass and need C++-style ad-
hoc overloading, it's likely you are trying to encode a fake
abstraction -- one
Am Donnerstag, 19. Februar 2009 12:37 schrieb Malcolm Wallace:
Unless Google's changed things, the organization gets 500$ for each
project. What the Darcs organization does with that, who knows.
Yes, who knows. The Haskell organization didn't give a cent
to the mentors, as far as I
Am Donnerstag, 19. Februar 2009 14:50 schrieb John A. De Goes:
Unfortunately the proofs in dependently typed languages are
extremely long and tedious to write. Some kind of compiler proofing
tool could ease the pain, but I do not think it has low enough
complexity for a GSoC project.
I was
On Thu, 2009-02-19 at 05:53 -0800, Kim-Ee Yeoh wrote:
There's a lot to chew on (thank you!), but I'll just take something
I can handle for now.
Dan Doel wrote:
An existential:
exists a:T. P(a)
is a pair of some a with type T and a proof that a satisfies P (which has
Hello Khudyakov,
Thursday, February 19, 2009, 4:06:06 PM, you wrote:
i think that FilePath=String is ok, we just need to use utf8 string
encoding on unix/macs and utf-16 encoding with *W functions on
Windows. i have implemented such support inside my own application, and
would be happy to
Hello Khudyakov,
Thursday, February 19, 2009, 5:00:03 PM, you wrote:
I have two questions. How could this function be used? I'm unable to imagine
any. Naive approach lead to nothing (no surprise):
fix (1:)
--
Best regards,
Bulatmailto:bulat.zigans...@gmail.com
On Feb 14, 2009, at 11:28 PM, wren ng thornton wrote:
John A. De Goes wrote:
On Feb 13, 2009, at 2:11 PM, Jonathan Cast wrote:
The compiler should fail when you tell it two mutually contradictory
things, and only when you tell it two mutually contradictory things.
By definition, it's not a
It does. In the most recent version, the full class declaration runs
class MonadST m where
type StateThread m
liftST :: ST (StateThread m) a - m a
and the StateThread propagates accordingly.
Louis Wasserman
wasserman.lo...@gmail.com
On Thu, Feb 19, 2009 at 2:10 AM, Sittampalam, Ganesh
By the way, the fact that least is in the sense of least defined
explains why fix (2^) gives an undefined:
The least defined fixpoint of any strict function (f : f _|_ = _|_)
is, by definition, undefined. And (2^) is strict.
2009/2/19 Derek Elkins derek.a.elk...@gmail.com:
On Thu, 2009-02-19 at
Each data type in Haskell contains one element, which is usually
invisible. It's called bottom and denoted by (_|_).
Naturally (_|_) of type Int and (_|_) of type Char are different;
however, they are denoted as if they are the same, 'cause there isn't
much difference between them. Anyway,
On Thu, Feb 19, 2009 at 7:09 AM, John A. De Goes j...@n-brain.net wrote:
On Feb 14, 2009, at 2:29 PM, Luke Palmer wrote:
To me, typeclasses are at their best when you have a real abstraction to
encode.
I agree.
If you are having trouble using a typeclass and need C++-style ad-hoc
Unfortunately the proofs in dependently typed languages are
extremely long and tedious to write. Some kind of compiler proofing
tool could ease the pain, but I do not think it has low enough
complexity for a GSoC project.
I wouldn't say that.
Here's the complete proof script in Coq
I agree that type classes should not be used for this purpose. That's
part of the reason I support linguistic overloading -- to stop the
type class abuse.
Type classes should be used, as you say, when there are algorithms
that work for arbitrary members -- i.e. the type class encodes
Thankyou everyone. This was most helpful.
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2009/2/19 Eugene Kirpichov ekirpic...@gmail.com:
Is there a typeclass for mappings with a Data.Map-like interface, with
stuff like: empty, insert, insertWithKey, unionWith etc. ?
Maybe this is of interest:
http://hackage.haskell.org/cgi-bin/hackage-scripts/package/gmap
Peter
I think the capabilities community including E and Coyotos/BitC have
extensively addressed this topic. Coyotos is taking the correct approach for
trusted voting platform. Since, even if your software is trustworthy, it
can't be trusted if the OS on which it runs is suspect. However, we might
have
I'm pleased to announce point-releases of the Cabal library and the
cabal-install command line tool.
If you are already using cabal-install then you can upgrade both using:
$ cabal update
$ cabal install Cabal cabal-install
New users you can get it from:
2009/2/19 Rick R rick.richard...@gmail.com
I think the capabilities community including E and Coyotos/BitC have
extensively addressed this topic. Coyotos is taking the correct approach for
trusted voting platform. Since, even if your software is trustworthy, it
can't be trusted if the OS on
2009/2/19 Luke Palmer lrpal...@gmail.com:
2009/2/19 Rick R rick.richard...@gmail.com
I think the capabilities community including E and Coyotos/BitC have
extensively addressed this topic. Coyotos is taking the correct approach for
trusted voting platform. Since, even if your software is
2009/2/19 Luke Palmer lrpal...@gmail.com
2009/2/19 Rick R rick.richard...@gmail.com
I think the capabilities community including E and Coyotos/BitC have
extensively addressed this topic. Coyotos is taking the correct approach for
trusted voting platform. Since, even if your software is
Hi
http://haskell.org/hoogle/?q=socket+%2Bnetwork
By default it searches the libraries supplied with Windows apart from
Network (for various technical reasons). If you add +network it will
then search the network library.
What libraries should Hoogle search by default? What flags should be
Niel,
Outside of flags to enable display of modules specific to each major
platform (+windows, +posix, +osx) I see two options. This all depends
on hoogle having some sort of list of modules for each platform, which
I believe would be the main problem.
1) Show all the functions (when the number
On Wed, Feb 18, 2009 at 6:50 PM, Thomas DuBuisson
thomas.dubuis...@gmail.com wrote:
I recall that Niel made sure hoogle doesn't search through
non-portable libraries (a shame), but I thought Network.Socket could
be used on Windows and yet Hoogle does not give any results for
'socket' or any
Maybe this is of interest:
http://hackage.haskell.org/cgi-bin/hackage-scripts/package/gmap
The edison api is much more stable. The gmap api was already in place
when I started working on it but I would prefer to at some point make
it a superset of the edison api. No sense in having more than
2009/2/19 Bryan O'Sullivan b...@serpentine.com:
On Wed, Feb 18, 2009 at 6:50 PM, Thomas DuBuisson
thomas.dubuis...@gmail.com wrote:
I recall that Niel made sure hoogle doesn't search through
non-portable libraries (a shame), but I thought Network.Socket could
be used on Windows and yet
Jonathan Cast-2 wrote:
Taking the `let open' syntax from `First-class
Modules for Haskell' [1], we can say
let open runST' = runST in
let
ref = runST' $ newSTRef 0
!() = runST' $ writeSTRef ref 1
!() = runST' $ writeSTRef ref 2
in runST' $ readSTRef ref
This
Hi,
Thanks for this very interesting and inspiring paper. I'm certainly
going to try some other data types, and see what kind of
implementations you get when using the TCM property.
I was wondering if any of this could be automated, given the semantic
function? If not in Haskell, then
So, why not use this definition? Is there something special about ST
you are trying to preserve?
-- minimal complete definition:
-- Ref, newRef, and either modifyRef or both readRef and writeRef.
class Monad m = MonadRef m where
type Ref m :: * - *
newRef :: a - m (Ref m a)
readRef
Oh, sweet beans. I hadn't planned to incorporate mutable references -- my
code uses them highly infrequently -- but I suppose that since mutable
references are really equivalent to single-threadedness where referential
transparency is concerned, that could be pulled off -- I would still want a
Alberto G. Corona wrote:
Wouldn't it be better to achieve the goals you describe with a dependently
typed programming language?
But I wonder how a dependent typed language can express certain properties,
for example, the distributive property between the operation + and * in a
ring or simply
* Wouter Swierstra w...@cs.nott.ac.uk [2009-02-19 11:58:38+0100]
There are several problems with this approach.
For example, I can show:
const 0 (head []) = 0
But if I pretend that I don't know that Haskell is lazy:
const 0 (head []) = const 0 (error ) = error ...
Where does the last
On Thu, 2009-02-19 at 23:06 +0200, Roman Cheplyaka wrote:
* Wouter Swierstra w...@cs.nott.ac.uk [2009-02-19 11:58:38+0100]
There are several problems with this approach.
For example, I can show:
const 0 (head []) = 0
But if I pretend that I don't know that Haskell is lazy:
const
Roman Cheplyaka schrieb:
Evaluation order matters for operational semantics, not for axiomatic.
And even in operational semantics Church–Rosser theorem should prevent
getting different results (e.g. 0 and error) for different evaluation
orders.
Let's consider
omega = omega
const omega 42
May be I am reading it wrong Shouldn't the second instance in The
instance's meaning is the meaning's instance be plural as meaning's
instances rather than meaning's instance?
I am reading it similar to the you are who you know saying. It seems to
say that the meaning of your data types
On Thu, Feb 19, 2009 at 01:51:44PM +0300, Eugene Kirpichov wrote:
Is there a typeclass for mappings with a Data.Map-like interface, with
stuff like: empty, insert, insertWithKey, unionWith etc. ?
And, probably, a similar typeclass for mutable mappings like Data.Hashtable.
Here is one I wrote a
Ryan, I didn't get your question after the first read, so here's an actual
answer to it --
What I want to preserve about ST is the existence of a guaranteed safe
runST, really. I tend to do algorithms and data structures development,
which almost never requires use of IO, or references of any
On 20 Feb 2009, at 3:24 am, John A. De Goes wrote:
It is precisely this abuse of notation which makes, for instance,
statistics textbooks impossible to read (without already knowing
the material).
Hmmm, I don't find statistics books difficult to read.
I'm interested in a technique called
Wolfgang Jeltsch schrieb:
Am Donnerstag, 19. Februar 2009 00:17 schrieben Sie:
Do you mean this one: http://haskell.org/haskellwiki/Numeric_Prelude?
There is currently no code for this, is there?
http://hackage.haskell.org/cgi-bin/hackage-scripts/package/numeric-prelude
On Thu, 19 Feb 2009, Wolfgang Jeltsch wrote:
Am Donnerstag, 19. Februar 2009 00:17 schrieben Sie:
Do you mean this one: http://haskell.org/haskellwiki/Numeric_Prelude?
There is currently no code for this, is there?
???
waterson:
On Feb 17, 2009, at 12:22 PM, Chris Waterson wrote:
I'm at wits end with respect to GHC's garbage collector and would very
much appreciate a code review of my MySQL driver for HDBC, which is
here:
http://www.maubi.net/~waterson/REPO/HDBC-mysql/Database/HDBC/MySQL/Connection.hsc
On Feb 19, 2009, at 3:41 PM, Don Stewart wrote:
Is the solution written up somewhere so we can point to that next
time?
:)
Well, the applicability to the community at large is probably minimal,
but my misadventure follows...
The MySQL C API has statements that are associated with a
On Thu, Feb 19, 2009 at 10:18 AM, Jamie Brandon jamii...@googlemail.com wrote:
Maybe this is of interest:
http://hackage.haskell.org/cgi-bin/hackage-scripts/package/gmap
The edison api is much more stable. The gmap api was already in place
when I started working on it but I would prefer to at
On Feb 18, 2009, at 4:43 AM, Max Bolingbroke wrote:
2009/2/18 Sterling Clover s.clo...@gmail.com:
The punchline: With GHC plugins, it should be possible, and
reasonable, to
add a proper unit system for Haskell.
Alas, GHC plugins cannot change the type system - only meddle with the
Eugene Kirpichov wrote:
Looks like such a thing would be useful; as for now, I see at least
two applications: Data.Map and Data.Trie (bytestring-trie) - it's a
pity that they have rather similar interfaces, but the latter lacks
many methods and some are named in a different way.
Are there any
On Feb 19, 2009, at 9:09 AM, John A. De Goes wrote:
Let's try a little test:
1. If the parameter is a tree, what do you think flatten
would do?
I would imagine that it would be join on trees -- i.e. take a tree
of trees and turn it into a tree. But perhaps it would be arbitrarily
Kim-Ee Yeoh said:
On the same note, does anyone have ideas
for the following snippet? Tried the pointfree
package but the output was useless.
pointwise op (x0,y0) (x1,y1) = (x0 `op` x1, y0 `op` y1)
First sorry for the delay in getting to this.. been behind on
projects so had some days of mail
On 2009 Feb 19, at 13:19, Svein Ove Aas wrote:
If you say so, but..
Unix domain sockets?
sendFd?
I can't speak to sendFd, but BITD OS/2 had AF_LOCAL (the portable
version of AF_UNIX; same API) sockets. There's no particular reason
aside from unwillingness that Windows wouldn't support
* Tillmann Rendel ren...@cs.au.dk [2009-02-19 22:43:24+0100]
Roman Cheplyaka schrieb:
Evaluation order matters for operational semantics, not for axiomatic.
And even in operational semantics Church–Rosser theorem should prevent
getting different results (e.g. 0 and error) for different
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