On Mon, Jul 26, 2010 at 10:59 PM, Jason Dagit da...@codersbase.com wrote:
($) is application, but in the space of functions it is identity. So, if
you think the elements in your thrist as being values in the space of
functions, you're asking for a right fold that is like, v1 `id` (v2 `id`
On Jul 27, 2010, at 7:09 AM, Sebastian Fischer wrote:
I find
eachOnce :: [RegExp c] - RegExp c
eachOnce = foldr alt noMatch . map (foldr seq_ eps) . permutations
even clearer but your version is *much* better as it uses nesting to
combine all alternatives that start with
On Jul 27, 2010, at 7:09 AM, Sebastian Fischer wrote:
I'll add
noMatch :: RegExp c
noMatch = psym [] (const False)
Oh, by the way, with noMatch, eps, alt and seq_ RegExp is itself a Semiring,
but I'm not sure what that would do.
--
Sjoerd Visscher
http://w3future.com
Perhaps this might mean that we can get incremental and parallel
regexp matching by associating each character with a linear operator
(matrix) over this or related semiring, or something, and mixing that
with two sigfpe's articles:
John Lato schrieb:
Hello,
I was wondering today, is this generally true?
instance (Monad m, Monoid a) = Monoid (m a) where
mempty = return mempty
mappend = liftM2 mappend
I know it isn't a good idea to use this instance, but assuming that
the instance head does what I mean, is it
I have released weighted-regexp-0.1.1.0 with two additional combinators:
-- | Does not match anything. 'noMatch' is an identity for 'alt'.
--
noMatch :: RegExp c
-- |
-- Matches a sequence of the given regular expressions in any
-- order. For example, the regular
(??) is misleading, some may be tempted to write things like: func ?? 45 ??
x , forgetting that ?? is just a mere operator, not a syntactic convenience.
Unfortunately, Haskell doesn't provide Scala's underscore for partially
applied functions: func(56, _, foo, _)
On Jul 27, 2010, at 9:15 AM, Sjoerd Visscher wrote:
Oh, by the way, with noMatch, eps, alt and seq_ RegExp is itself a
Semiring,
Yes, but it's hard to define an Eq instance for arbitrary regular
expressions that reflects equivalence of regexps.
There is currently only `instance Eq
Sorry if I have left typos, it's very late
I knew it was a bit late to be uploading things, I forgot to say where
anyone interested might download this:
it's on Hackage so just
cabal install snm
Cheers
Johnny
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Lennart Augustsson wrote:
Try to make Set an instance of Functor and you'll see why it isn't.
It's very annoying.
And yet the very simple, and old solution works.
http://okmij.org/ftp/Haskell/types.html#restricted-datatypes
We just properly generalize Functor, so that all old
But that's not really a solution, since it doesn't make a Functor
instance for Set; it makes a Functor' instance for Set.
If you are willing to not be upwards compatible then, yes, there are solutions.
I think the best bet for an upwards compatible solutions is the
associated constraints,
On Tue, Jul 27, 2010 at 8:32 AM, Henning Thielemann
schlepp...@henning-thielemann.de wrote:
John Lato schrieb:
Hello,
I was wondering today, is this generally true?
instance (Monad m, Monoid a) = Monoid (m a) where
mempty = return mempty
mappend = liftM2 mappend
I know it isn't a
On Mon, Jul 26, 2010 at 5:02 PM, Edward Kmett ekm...@gmail.com wrote:
On Mon, Jul 26, 2010 at 11:55 AM, John Lato jwl...@gmail.com wrote:
Hello,
I was wondering today, is this generally true?
instance (Monad m, Monoid a) = Monoid (m a) where
mempty = return mempty
mappend = liftM2
Brandon S Allbery KF8NH allb...@ece.cmu.edu writes:
Usenet *is* NNTP.
In the same way the web is HTTP...
(Usenet is a set of global, distributed forums using a message format
similar enough to email (RFC822 + extensions) that many mail reader
software supports news, and vice versa. NNTP is
o...@okmij.org writes:
class Functor' f a b where
fmap' :: (a - b) - f a - f b
I was about to ask why you mentioned b in the type signature as well, as
I thought just having (Functor' f b) as a constraint in the type
signature of fmap' would be sufficient, but when I went to check I found
Dear Jason,
And yes, Orc is pretty cool and should be perfectly suited for what you're
doing as fetching data from websites was one of the original use cases for
Orc.
Jason
thanks for that, it's nice to be on the right track for once.
Günther
___
Hi Yves,
You say that With the help of this library it is possible to build
Erlang-Style mailboxes, but how would you solve the issue of static typing?
this wasn't an issue for me because I wanted as much type checking as
possible. In many implementations, you have an implicit contract
On Tue, Jul 27, 2010 at 12:09 AM, aditya siram aditya.si...@gmail.com wrote:
We have a Google group. Doesn't that qualify?
One can't post to Haskell Cafe through the usenet/NNTP/google group interface...
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John Lato schrieb:
Hello,
I was wondering today, is this generally true?
instance (Monad m, Monoid a) = Monoid (m a) where
mempty = return mempty
mappend = liftM2 mappend
I know it isn't a good idea to use this instance, but assuming that
the instance head does what I mean, is it
On Tue, Jul 27, 2010 at 5:27 AM, Stefan Schmidt
stefanschmid...@googlemail.com wrote:
Hi Yves,
You say that With the help of this library it is possible to build
Erlang-Style mailboxes, but how would you solve the issue of static typing?
this wasn't an issue for me because I wanted as
This may not be of direct interest to the Haskell community but I thought
I'd share this information anyway.
If you are looking for a solution (in Erlang that runs on Erlang's virtual
machine) to enforce an explicit contract between a client and a server,
there is framework called UBF.
On Tuesday 27 July 2010 8:50:56 am Henning Thielemann wrote:
I always assumed that 'm a' would be a monoid for 'm' being an
applicative functor, but I never tried to prove it. Now you made me
performing a proof. However the applicative functor laws from
aditya siram wrote:
Eta-reducing is nice, and sometimes it makes code more readable. But 'flip'
is one of those functions that always seems to hinder rather than help
readability, conversely factoring out flip always makes code easier to
comprehend. I don't see a need for its existence - maybe
Kevin Jardine wrote:
But as I said, that is just an example. I keep wanting to apply the
usual list tools but find that they do not work inside a monad. I find
myself wishing that f (m [a]) just automatically returned m f([a])
Are you looking for these?
import Data.Traversable as T
Henning Thielemann wrote:
However the applicative functor laws from
http://www.haskell.org/ghc/docs/6.12.2/html/libraries/base-4.2.0.1/Control-Applicative.html
are quite unintuitive and the proofs are certainly not very
illustrative.
I always found it more illustrative to break it down and
On Tue, Jul 27, 2010 at 1:59 AM, Jason Dagit da...@codersbase.com wrote:
On Mon, Jul 26, 2010 at 9:00 PM, Brandon Simmons
brandon.m.simm...@gmail.com wrote:
I had the idea for a simple generic Zipper data structure that I
thought would be possible to implement using type-threaded lists
Magnus Therning wrote:
On 26/07/10 22:01, Andrew Coppin wrote:
So I'm told. But it appears that some people believe that NNTP *is*
Usenet, which is not the case. I use NNTP almost every single day, but
I've never seen Usenet in my life...
So you've only ever been on private NNTP
John Meacham wrote:
There already is an NNTP - mailing list gateway via gmane that gives a
nice forumy and threaded web interface for those with insufficient email
readers. Adding a completely different interface seems unnecessary and
fragmentary.
Trouble is, you can't use it like just
Hey all,
Is there a library function (f :: [Int] - ByteString) such that it's
prefix-preserving, and platform independent? GHC-only is fine for now.
There are a bunch of functions of that type, but I need those guarantees
and I'm hoping someone else has already done it.
If there isn't one
From my experience once a forum pops up the mailing list dies.
--
Mihai Maruseac
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I've found that I like Erlang's pattern matching for sorting through
different kinds of data payloads, but that I prefer to use typed data
channels per Limbo, Go, Plan 9's thread and messaging libraries etc. I've
often wanted an Erlang with static typing to get this capability.
Actually you are
Looks interesting.
I've also come across Data.List.Class:
http://hackage.haskell.org/packages/archive/generator/0.5.1/doc/html/Data-List-Class.html
Has anyone used that?
Kevin
On Jul 27, 6:02 pm, wren ng thornton w...@freegeek.org wrote:
Kevin Jardine wrote:
But as I said, that is just an
On Tue, Jul 27, 2010 at 07:01:45PM +0100, Andrew Coppin wrote:
If you have a forum powered by NNTP, you can casually throw in a
hey, nice one time comment as a reply to part of a thread, and
only people interested in that thread have to see your message (or
download it, for that matter).
...
wren:
Hey all,
Is there a library function (f :: [Int] - ByteString) such that it's
prefix-preserving, and platform independent? GHC-only is fine for now.
There are a bunch of functions of that type, but I need those guarantees
and I'm hoping someone else has already done it.
should
I'd add another parameter to the ExprType class and give an explicit
representation to your types.
data EType a where
EInt :: EType Int
EBool :: EType Bool
data TypeEq a b where Refl :: TypeEq x x
eqEType :: ExprType a - ExprType b - Maybe (TypeEq a b)
eqEType EInt EInt = Just Refl
Hi, All.
I have a compiler written in Parsec and Haskell for a DSL. It's quite
rudimentary since I made it for my own use only. I would like to make it
useable by a slightly wider circle. For this, I need better error reporting.
Currently, it terminates after finding one syntax error. I
Darrin Chandler wrote:
IOW, if people use the proper and well known features of NNTP it would
be a better world than the one we have were people do not use proper and
well known features of SMTP.
SMTP is designed for delivering messages point-to-point. If your email
provider incorrectly
On 2010-07-27 19:59 +0100, Andrew Coppin wrote:
Darrin Chandler wrote:
IOW, if people use the proper and well known features of NNTP it would
be a better world than the one we have were people do not use proper and
well known features of SMTP.
SMTP is designed for delivering messages
On Tue, Jul 27, 2010 at 07:59:40PM +0100, Andrew Coppin wrote:
NNTP is
...
It's all true. I used nntp extensively in the 90s. I never emo-quit, I
just stopped using it over time due to waning ISP support and other
reasons made it more of a pain. I have nothing against nntp as a
protocol, but I
Hello
I'm wondering is there any haskellers in CERN? Given quality
and usability of software there must be people looking for
better alternatives.
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Hi,
I´m streaming content using lazy bytestrings in a web application. The
problem is that the output comes in huge blobs (presumably of 32k)
one at a time. This is good for some purposes, but not for
console-like interfaces or runtime log visualization. (one of my
purposes is to web-alize ghci.
On Tue, 27 Jul 2010, Alberto G. Corona wrote:
The question is: are there some way to control bytestring streaming?.
Can It be done without the stream handler?
I think there is a function that converts a lazy ByteString to a list of
strict ByteStrings, that should work without copying the
Rogan:
Thanks very much.
I began by downloading the latest gtk+ bundle from
http://www.gtk.org/download-windows.html
The instructions there said to just copy the files to any dir and add its
...\gtk\bin dir to my PATH, which I did, so that worked okay without admin
privs.
Given that I need to
Reading the Control.Monad.Error documentation, I see that the Error class
has noMsg and strMsg as its only two functions.
Now, I understand that you can define your own Error instances such as in
example 1 of the documentation, so why the need to always support strings
via noMsg/strMsg ? What
It is for the very annoying reason that in order for Error to be a monad
it has to implement the fail method, which means it has to know how to
turn an arbitrary string into a value of your error type.
Cheers,
Greg
On 07/27/10 15:32, Gerald Gutierrez wrote:
Reading the Control.Monad.Error
The strMsg method is used to implement the fail method in the
resulting method, and calls to fail might be inserted into your code
even if you don't explicitly call it. An example in GHCi:
Prelude :m + Control.Monad.Error
Prelude Control.Monad.Error do { Just x - return Nothing ; return
x
On Tue, Jul 27, 2010 at 3:57 PM, Dietrich Epp d...@zdome.net wrote:
The strMsg method is used to implement the fail method in the resulting
method, and calls to fail might be inserted into your code even if you
don't explicitly call it. An example in GHCi:
Prelude :m + Control.Monad.Error
I'll say yes, a pattern match failure is a bug. This is one of the
great debates in the language: whether all pattern matching code
should be guaranteed complete at compile time or not. However, any
function you call which returns a result in your monad could
theoretically call fail if
Kevin Jardine kevinjard...@gmail.com writes:
On Jul 26, 6:45 pm, Nick Bowler nbow...@elliptictech.com wrote:
Since when do mailing lists not have threading? Web forums with proper
support for threading seem to be few and far apart.
Most of the email clients I'm familiar with don't support
Nick Bowler nbow...@elliptictech.com writes:
On 13:58 Mon 26 Jul , John Meacham wrote:
There already is an NNTP - mailing list gateway via gmane that gives a
nice forumy and threaded web interface for those with insufficient email
readers. Adding a completely different interface seems
On Tue, Jul 27, 2010 at 6:29 PM, Dietrich Epp d...@zdome.net wrote:
I'll say yes, a pattern match failure is a bug. This is one of the great
debates in the language: whether all pattern matching code should be
guaranteed complete at compile time or not. However, any function you call
which
On Mon, 26 Jul 2010 21:54:16 -0700
Thomas DuBuisson thomas.dubuis...@gmail.com wrote:
Can you boil this down to some simple example code? Are you using a
recent version of Chart? And your definition of latest gtk2hs is
11, right? How about your gtk+ C library, it what? 2.20?
I can run
How do I import Control.Monad.State?
I see this note in
http://en.wikibooks.org/wiki/Haskell/Understanding_monads/State
Note: in some package systems used for GHC, the Control.Monad.State module is
in a separate package, usually indicated by MTL (Monad Transformer Library).
Michael
On 28 July 2010 12:39, michael rice nowg...@yahoo.com wrote:
How do I import Control.Monad.State?
Install and use the mtl library (comes with the Haskell platform),
monads-fd (almost identical API to mtl; the point of this is that mtl
uses some extension: the non-extension bits are in the
[mich...@localhost ~]$ ghc-pkg list mtl
/usr/lib/ghc-6.12.1/package.conf.d
[mich...@localhost ~]$
Installed?
Michael
--- On Tue, 7/27/10, Ivan Miljenovic ivan.miljeno...@gmail.com wrote:
From: Ivan Miljenovic ivan.miljeno...@gmail.com
Subject: Re: [Haskell-cafe] Need Control.Monad.State
To:
On 28 July 2010 13:03, michael rice nowg...@yahoo.com wrote:
[mich...@localhost ~]$ ghc-pkg list mtl
/usr/lib/ghc-6.12.1/package.conf.d
[mich...@localhost ~]$
Installed?
No; if it was installed it would specify a version.
Michael
--- On Tue, 7/27/10, Ivan Miljenovic
On Wed, Jul 28, 2010 at 12:04 AM, Ivan Miljenovic
ivan.miljeno...@gmail.com wrote:
On 28 July 2010 13:03, michael rice nowg...@yahoo.com wrote:
[mich...@localhost ~]$ ghc-pkg list mtl
/usr/lib/ghc-6.12.1/package.conf.d
[mich...@localhost ~]$
Installed?
No; if it was installed it would
See below. Lot's of warnings. Is the install OK? If so, can I use the same
*import*?
Michael
--- On Tue, 7/27/10, Ivan Miljenovic ivan.miljeno...@gmail.com wrote:
If it isn't installed, you can use cabal-install to install it:
cabal install mtl
--
Ivan Lazar Miljenovic
On 28 July 2010 13:17, michael rice nowg...@yahoo.com wrote:
See below. Lot's of warnings. Is the install OK? If so, can I use the same
*import*?
Yeah, the install is OK. The meaning of the warnings are:
* Warning: -fallow-undecidable-instances is deprecated: this GHC
option has changed
I didn't realize the State monad wasn't part of the base install. Any
particular reason for this?
-deech
On Tue, Jul 27, 2010 at 10:24 PM, Ivan Miljenovic ivan.miljeno...@gmail.com
wrote:
On 28 July 2010 13:17, michael rice nowg...@yahoo.com wrote:
See below. Lot's of warnings. Is the
On Tue, Jul 27, 2010 at 2:43 PM, Peter Schmitz ps.hask...@gmail.com wrote:
So, by default, cabal wants to put its config and updates on C:.
I looked at C:\Documents and Settings\pschmitz\Application Data\cabal\config
It has various references to C:, some commented out. E.g.:
On 28 July 2010 14:07, aditya siram aditya.si...@gmail.com wrote:
I didn't realize the State monad wasn't part of the base install. Any
particular reason for this?
Because there's no reason for it to be? GHC is bundled with enough
libraries as it is (and with the exception of Cabal, it's not
Don Stewart wrote:
wren:
Hey all,
Is there a library function (f :: [Int] - ByteString) such that it's
prefix-preserving, and platform independent? GHC-only is fine for now.
There are a bunch of functions of that type, but I need those guarantees
and I'm hoping someone else has already
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