On Mon, 5 Jan 2009 07:27:13 +0100
Achim Schneider wrote:
> Achim Schneider wrote:
>
> > [...]
> >
> Hmmm... I seem to have left out the academics definition of bogosity.
> I bet that others are much more qualified to elaborate on this, but my
> working assumption has been (and still is) that it
Hi,
> I think that
> >>> class HeaderOf addr hdr | addr -> hdr
> does not enforce that there must be a corresponding instance
> AddressOf hdr addr. Hence, the type checker cannot use that information
> either. Do you have a way to remedy that?
I've often wanted something similar, and experimentin
Achim Schneider wrote:
> [...]
>
Hmmm... I seem to have left out the academics definition of bogosity. I
bet that others are much more qualified to elaborate on this, but my
working assumption has been (and still is) that it does include a wide
range of working code, and excludes a lot of abstrac
"Jamie Brandon" wrote:
> The haskell community has a well deserved reputation for being one of
> the friendliest online communities. Perhaps this would be a good point
> to figure out what we're doing right? I'm convinced that part of it is
> that offtopic conversation is encouraged through on ha
Lauri Alanko wrote:
> Personally, I find the idea appealing (and have implemented the Refs
> in the paper with IORefs and unsafePerformIO), because really, even
> currently a programmer has to care about sharing since it can have
> radical implications for performance and memory usage. Making it
On Sun, 2009-01-04 at 19:47 -0600, Drew Vogel wrote:
> I saw a blog entry once (sorry, google can't seem to find it now)
> proposing the idea that OOP really is just language support for CPS
> (continuation-passing-style). Does anyone have a link to this?
'don't think I've heard of it, but it soun
Original Message
Message-ID: <496176cf.3090...@freegeek.org>
Date: Sun, 04 Jan 2009 21:56:15 -0500
From: wren ng thornton
User-Agent: Thunderbird 2.0.0.16 (Macintosh/20080707)
MIME-Version: 1.0
To: ChrisK
Subject: Re: ANN: bytestring-trie 0.1.1 (bugfix)
References: <494c8b52.
Dear Haskellers,
I just got an inquiry from a research department head
of a Korean company seriously considering to adopt
functional languages because they heard that functional
languages can do good at parallel programming on manycore
platforms.
They want to know what technologies out there impl
I saw a blog entry once (sorry, google can't seem to find it now)
proposing the idea that OOP really is just language support for CPS
(continuation-passing-style). Does anyone have a link to this?
Drew
Kevin Van Horn wrote:
> Haskell has been around in one form or another for nearly two decades
Maybe you could use stable names for this:
http://www.haskell.org/ghc/docs/latest/html/libraries/base/System-Mem-StableName.html
"Stable names are a way of performing fast (O(1)), not-quite-exact
comparison between objects. Stable names solve the following problem:
suppose you want to build a has
Aaron Tomb writes:
> As others have explained, the == operator doesn't tell you whether two
> values are actually stored at the same location in memory.
Nobody yet mentioned that (==) doesn't guarantee *anything* - it's a
user defined function. So while it may and should give structural
equalit
Forwarding response to cafe
-- Forwarded message --
From: Antoine Latter
Date: Sun, Jan 4, 2009 at 2:13 PM
Subject: Re: [Haskell-cafe] Auto-deriving Control.Exception.Exception
To: "eyal.lo...@gmail.com"
On Sun, Jan 4, 2009 at 11:50 AM, eyal.lo...@gmail.com
wrote:
> If this i
Thanks everybody for your responses, they helped a lot. And sorry for my
misconcept on JSON. ;]
Sterling Clover, Nov 30, 2008:
>These days, however, web services seem to be moving towards a RESTful
>model with a JSON layer and there are plenty of JSON libraries on
>hackage, which you could ju
On Sat, 3 Jan 2009, Henning Thielemann wrote:
I think I now have general Applicative functionality ...
I hope the following is a proper Monad implementation. In contrast to
Applicative a Writer for sequencing actions does no longer work, instead I
need a State monad.
newtype LazyIO a = L
Question and suggestion:
looking at
http://hackage.haskell.org/packages/archive/bytestring-trie/0.1.1/doc/html/src/Data-Trie.html#Trie
I am questioning your choice of foldr in fromList:
-- | Convert association list into a trie. On key conflict, values
-- earlier in the list shadow later ones.
If this is valid:
import qualified Control.Exception as Exc
genericFromException :: Typeable a => Exc.SomeException -> Maybe a
genericFromException (Exc.SomeException e) = cast e
instance Exc.Exception SomeType where fromException =
genericFromException
then why not have an auto-
Warren Harris wrote:
I am seeking suggestions from the haskell cafe for teaching functional
programming concepts to colleagues at work.
I'd suggest starting with a couple of hours of "Why Haskell" talk to
sell them on the concepts, followed by something like the the study
group you mentioned f
Hi Thomas,
The specific problem you describe has a simple solution using
multiple parameter classes with syntactic sugar for functional
notation instead of type families [1]:
> class AddressOf h a | h -> a, a -> h -- bijections
> class HeaderOf a h | a -> h, h -> a
> instance HeaderOf (Address
On 4 Jan 2009, at 18:08, Aaron Tomb wrote:
On Jan 3, 2009, at 7:28 AM, Xie Hanjian wrote:
Hi,
I tried this in ghci:
Prelude> 1:2:[] == 1:2:[]
True
Does this mean (:) return the same object on same input, or
(==) is not for identity checking? If the later is true, how
can I check two obje
On Jan 3, 2009, at 7:28 AM, Xie Hanjian wrote:
Hi,
I tried this in ghci:
Prelude> 1:2:[] == 1:2:[]
True
Does this mean (:) return the same object on same input, or
(==) is not for identity checking? If the later is true, how
can I check two object is the *same* object?
As others have expl
The wxHaskell development team is pleased to announce the release of
wxHaskell 0.11.1, a Haskell binding for the wxWidgets GUI library.
The Haskell support is built on a reasonably complete C language
binding, which could be used as the basis for wxWidgets support on other
languages/platforms whic
Hi Warren,
I'd recommend getting them to read Why FP Matters
(http://www.cs.chalmers.se/~rjmh/Papers/whyfp.html) to tempt them,
followed by Programming in Haskell
(http://www.cs.nott.ac.uk/~gmh/book.html) to teach them the
concepts/syntax etc, possibly with Learn You a Haskell
(http://learnyouahas
Hi,
I like collecting examples of different type system related issues,
and I am curious in what way is the solution that I posted limited. Do
you happen to have an example?
Hi Iavor,
I think that
class HeaderOf addr hdr | addr -> hdr
does not enforce that there must be a corresponding inst
Hello, community people!
Is anybody aware, what aproximately is the cost for the acquiring connection
to DB (and also disconnecting from it)? I guess that may differ from DBMS to
DBMS, so I mostly am interested in PostgreSQL case, but for other DBMS it's
also good to know.
Actually, since all H
On Sun, Jan 04, 2009 at 04:19:38PM +0800, Evan Laforge wrote:
> If you don't have set-car!, then identity and equality are impossible
> to differentiate.
There's still eqv?. (I wish people wouldn't use eq? as an example of
an identity-comparison operation. It's as underdefined as
unsafePtrEq.)
So
Hi,
I like collecting examples of different type system related issues,
and I am curious in what way is the solution that I posted limited. Do
you happen to have an example?
Thanks,
Iavor
On Sat, Jan 3, 2009 at 8:35 PM, Thomas DuBuisson
wrote:
> Thank you all for the responses. I find the soluti
On 4 Jan 2009, at 07:11, Thomas DuBuisson wrote:
My proposal would be for each selector name to be a special type of
"phantom" type class (existing in the intermediate language only).
This type class would not be accessible by the programmer and thus
s/he couldn't make a polymorphic function fo
>> So it *looks* like there's only one list created in 'lvl1', but I
>> can't see where it's turning into a tuple, and I don't understand the
>> ' = : ' stuff,
>
> You're reading it wrong. : is a name.
> It's lvl5 = (:) @ Char a2 ([] @ Char) where @ is type application
> (instantiation). Triming t
* Evan Laforge [2009-01-04 16:19:38 +0800]:
> > Although equal? treats the two as the *same*, they're different lists
> > because if we modify one (e.g by set-car!) the other won't be affected.
> >
> > So here comes another question: when we say a function always give the
> > same output for the
On Sun, 2009-01-04 at 16:19 +0800, Evan Laforge wrote:
> > Although equal? treats the two as the *same*, they're different lists
> > because if we modify one (e.g by set-car!) the other won't be affected.
> >
> > So here comes another question: when we say a function always give the
> > same output
> Although equal? treats the two as the *same*, they're different lists
> because if we modify one (e.g by set-car!) the other won't be affected.
>
> So here comes another question: when we say a function always give the
> same output for the same input, what the *same* means here? ídentity
> or eq
"Max cs" wrote:
> hi all, not sure if there is someone still working during holiday
> like me : )
>
> I got a little problem in implementing some operations on tree.
>
> suppose we have a tree date type defined:
>
> data Tree a = Leaf a | Branch (Tree a) (Tree a)
>
> I want to do a concatenat
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