Hello Vimal,
Sunday, October 14, 2007, 2:44:05 PM, you wrote:
> Dear Haskellers,
> I have been trying my best to read about Haskell from the various
first time when i tried to learn haskell i give up and returned only a
year later :) about IO: you may try to read
http://haskell.org/haskellwiki/
Hello Andrew,
Friday, October 12, 2007, 9:21:07 PM, you wrote:
> I notice that getDirectoryContents appears to return its results in
> alphabetical order. Is this behaviour actually guaranteed?
on NTFS filesystem, files are stored in directory alphabetically
sorted. on FAT disks the order may b
On Oct 19, 2007, at 15:14 , Andrew Coppin wrote:
Peter Verswyvelen wrote:
I find it a petty the library does not work with GHCi :-( It has
to do with the threaded RTS I guess. Any hints how I could fix this?
Yeah, lots of things seem to dislike running in GHCi. (I'm guessing
this is to d
Peter Verswyvelen wrote:
Yeah I missed that too at first sight... A hint to the author: rename
this into README.WIN32.txt or something :-)
But I don't think the author of that library reads this mailing list?
Mmm... I suppose technically somebody could submit a Darcs patch? ;-)
[Darcs even h
>I find it a petty the library does not work with GHCi :-( It has to do
>with the threaded RTS I guess. Any hints how I could fix this?
Not sure how useful this is, but it works for me. I have a toy project
that uses OpenGL and SDL and I have no problems running it from within
GHCi in Linux. Perh
If I understand what you're going for with the code below, then here's
another way to program it in SML that doesn't use exceptions (the
control flow mechanism) at all.
I think what you want is an extensible datatype. Here's the interface I
program to:
signature TAGGED =
sig
(* a tag is th
Paul Brown wrote:
On 10/17/07, PR Stanley <[EMAIL PROTECTED]> wrote:
Do you trust mathematical materials on Wikipedia?
I trust most of them to not be wrong, but I don't trust them to be right.
Mathematical concepts are bit like binary search -- getting the flavor
right isn't that diff
Hello Simon,
Thursday, October 11, 2007, 1:42:31 PM, you wrote:
> For various applications (including identifying common
> sub-expressions, and version tracking in GHC), I'd like a Haskell
> library that supports simple fingerprint operations.
lots of hash-related links was collected at
http://
Hi,
I extended the hyperlinked Haskell 98 grammar so that each
production now contains also links to all the sections
in the online report which explicitly name it.
I needed it few times myself so I added it. Some people
expressed interest so they may want to check out the update.
Javascript
On 10/17/07, PR Stanley <[EMAIL PROTECTED]> wrote:
> Do you trust mathematical materials on Wikipedia?
I trust most of them to not be wrong, but I don't trust them to be right.
Mathematical concepts are bit like binary search -- getting the flavor
right isn't that difficult, but being concise, co
Hi Greg
I forgot to say, that I did not stop using the Shelarcy patch because
there was something wrong with the code. On the contrary it served me
well for long time.
The reason for using the HappS-version was that I wanted something that
was Cabalized and that I thought it was good to minimize
Hi Greg
To the best of my knowledge it is not maintained anymore :(
If you want to use it, you should properly make use of this patch:
http://autoforms.svn.sourceforge.net/viewvc/autoforms/trunk/AForms/SYB3_Shelarcy.diff?revision=234&view=markup&pathrev=400
The patch was made by Kido Takahiro (ak
Jules Bean wrote:
> This looks very very much clearer in GADT syntax, since in GADT syntax
> you always give constructors explicit types:
>
> type ExistsNumber where
>Number :: forall a . Num a => ExistsNumber a
The questions in response to my post have been answered already; I'd like to
men
Yeah I missed that too at first sight... A hint to the author: rename
this into README.WIN32.txt or something :-)
But I don't think the author of that library reads this mailing list?
I find it a petty the library does not work with GHCi :-( It has to do
with the threaded RTS I guess. Any hin
I realise belatedly that my message might have sounded dismissive. My
apologies; it wasn't intended to be. Good ideas are just that: good.
Reinventing them is a sign of good taste.
As to documenting GHC, we try to do that by writing papers. That's easy to
motivate because we get research br
Dan Licata: Thanks for explaining the mechanics behind it. Knowing how
it (could) be implemented always helps me understand things.
On 10/20/07, Jules Bean <[EMAIL PROTECTED]> wrote:
> Quite often an explicit ADT is much nicer. But they represent two
> opposing patterns of code-writing. Explicit
On 10/17/07, Thomas Hartman <[EMAIL PROTECTED]> wrote:
>
>
> Is there a more scientific way of figuring out if one version is better
> than the other by using, say profiling tools?
Profiling Haskell programs is black magic, but of the sort you learn by
having a problem to solve. I don't think it
Will hackage docs use haddock 2.0 any time soon, for libraries that use
language extensions not supported by the older haddock?
On 10/19/07, Ross Paterson <[EMAIL PROTECTED]> wrote:
>
> On Fri, Oct 19, 2007 at 11:31:06AM +0200, Johan Tibell wrote:
> > Maybe I'm seeing things but from what I rememb
Simon Peyton-Jones wrote:
Good idea. GHC uses it
http://darcs.haskell.org/ghc/compiler/basicTypes/UniqSupply.lhs
Lennart Augustsson and friends invented it
@techreport{Augustsson92a,
...
You know what would be really nice? A summary of "here are all the
really cool tricks we use in
Sebastian Sylvan wrote:
On 19/10/2007, Kalman Noel <[EMAIL PROTECTED]> wrote:
data ExistsNumber = forall a. Num a => Number a
I'm without a Haskell compiler, but shouldn't that be "exists a."?
IIRC forall will work too, but the "right" way to do it is "exists",
right?
No. It's been sugges
TJ wrote:
Why is it illegal to store values of differing types, but which
instance the same class, into a list? e.g.
a = [ 1, 2.0 ] :: Num a => [a]
That type signature doesn't mean what you want it to mean. That reads
"A list of things of type a ([a]) with the restriction that the type a
is
On Oct 19, 2007, at 12:11 , Sebastian Sylvan wrote:
On 19/10/2007, Kalman Noel <[EMAIL PROTECTED]> wrote:
data ExistsNumber = forall a. Num a => Number a
I'm without a Haskell compiler, but shouldn't that be "exists a."?
The problem is that "exists" is not valid in either Haskell 98 or
You've almost got it right below. Here's an example of using existentials:
{-# OPTIONS -fglasgow-exts #-}
data AnyNum where
E :: forall a. Num a => a -> AnyNum
l :: [AnyNum]
l = [E (1 :: Integer), E (2.0 :: Float)]
neg :: [AnyNum] -> [AnyNum]
neg = map (\ (E x) -> E (0 - x))
-- testing:
On 19/10/2007, Kalman Noel <[EMAIL PROTECTED]> wrote:
>
>data ExistsNumber = forall a. Num a => Number a
I'm without a Haskell compiler, but shouldn't that be "exists a."?
IIRC forall will work too, but the "right" way to do it is "exists",
right?
So to avoid confusion, use "exists" rather tha
TJ wrote:
> Why is it illegal to store values of differing types, but which
> instance the same class, into a list? e.g.
>
> a = [ 1, 2.0 ] :: Num a => [a]
The problem is that Num a => [a] really means:
forall a. Num a => [a]
That is, a list of type Num a => [a] could either be a list of In
Henning Thielemann:
> > class Renderable a where
> > render :: a -> RasterImage
> >
> > scene :: Renderable a => [a]
>
> This signature is valid, but it means that all list elements must be of
> the same Renderable type.
Yes, that's exactly the restriction I'm unhappy about.
> You could let the
On Fri, 19 Oct 2007, TJ wrote:
> Why is it illegal to store values of differing types, but which
> instance the same class, into a list? e.g.
>
> a = [ 1, 2.0 ] :: Num a => [a]
>
> After all, sometimes all you need to know about a list is that all the
> elements support a common set of operations
Good idea. GHC uses it
http://darcs.haskell.org/ghc/compiler/basicTypes/UniqSupply.lhs
Lennart Augustsson and friends invented it
@techreport{Augustsson92a,
author = {L Augustsson and M Rittri and D Synek},
title = {Splitting infinite sets of unique names by hidden state changes},
Why is it illegal to store values of differing types, but which
instance the same class, into a list? e.g.
a = [ 1, 2.0 ] :: Num a => [a]
After all, sometimes all you need to know about a list is that all the
elements support a common set of operations. If I'm implementing a 3d
renderer for examp
Henning Thielemann <[EMAIL PROTECTED]> writes:
> Most proofs in mathematics use intuitive arguments, most proofs are not
> formalized enough in order to be checked by machines. Ok, this can be
> considered a deficiency of machine provers. But in the history there were
> famous "proofs" which turne
On Fri, 19 Oct 2007, Jules Bean wrote:
> [EMAIL PROTECTED] wrote:
> > *PLEASE*, show me untrustworthy Wikipedia pages.
>
> Any article on a disputed territory or open political dispute.
>
> Most articles on a controversial philosophy.
>
> Many articles on living people.
Articles on controversal
While thinking about how to generate unique integer IDs on demand without using
a state variable, I came up with an interesting design pattern. It's a way of
doing side-effecting computation outside IO. Referential transparency is
preserved by making the side effects spatial rather than tempo
On Fri, Oct 19, 2007 at 11:31:06AM +0200, Johan Tibell wrote:
> Maybe I'm seeing things but from what I remember packages that used to
> have links to Haddock documentation in their exported modules list no
> longer has. It's a super useful feature! What happened to those
> packages?
Documentation
[EMAIL PROTECTED] wrote:
*PLEASE*, show me untrustworthy Wikipedia pages.
Any article on a disputed territory or open political dispute.
Most articles on a controversial philosophy.
Many articles on living people.
I hope I don't have to give examples. Certainly I don't wish to discuss
any o
On Oct 19, 2007, at 8:18 , Simon Marlow wrote:
Ketil Malde wrote:
"Claus Reinke" <[EMAIL PROTECTED]> writes:
Incedentally, this reminds me that GHC should have a warning for
not
using explicit import lists (perhaps only for external package
imports).
for package-level imports/exports, that
Ross Paterson wrote,
On Tue, Oct 16, 2007 at 10:56:27AM +1000, Manuel M T Chakravarty wrote:
Lennart Augustsson wrote,
And Haskell embedded a logical programming language on accident.
Well, we are just trying to fix that :)
Since types are inferred using unification, and classes are still pr
Ketil Malde wrote:
"Claus Reinke" <[EMAIL PROTECTED]> writes:
Incedentally, this reminds me that GHC should have a warning for not
using explicit import lists (perhaps only for external package
imports).
for package-level imports/exports, that sounds useful.
Isn't there a secret key combin
Hi John,
I wrote:
>> - Zero really means 0, not "0 or negative"
You wrote:
> Actually, zero does mean zero. There is no such thing as negative
> numbers in the naturals so it doesn't make sense to say '0 or negative'.
Well, then, "0 or error", or "0 or nothing". It clearly
does not mean zero.
>
I agree with Matthew's comments in the post immediately before this. It
takes him two decent paragraphs to explain what is going on, including a
description of WHNF, a suggestion to use pen & paper, a suggestion to
read up on the semantics of unsafeInterleaveIO and more.
What I find inconceiva
On 10/19/07, Valery V. Vorotyntsev <[EMAIL PROTECTED]> wrote:
> On 10/19/07, Johan Tibell <[EMAIL PROTECTED]> wrote:
> >
> > If you have a web server somewhere you can use CGIIRC. That's what I
> > did in a similar situation.
> >
> > http://cgiirc.org/
>
> Thanks, Johan!
There is one at http://irc
On 10/19/07, Johan Tibell <[EMAIL PROTECTED]> wrote:
>
> If you have a web server somewhere you can use CGIIRC. That's what I
> did in a similar situation.
>
> http://cgiirc.org/
Thanks, Johan!
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http:
Simon Peyton-Jones writes:
> | I believe that this "weak coverage condition" (which is also called
> | "the dependency condition" somewhere on the wiki) is exactly what GHC
> | 6.4 used to implement but than in 6.6 this changed. According to
> | Simon's comments on the trac ticket, this rule r
On 10/19/07, Valery V. Vorotyntsev <[EMAIL PROTECTED]> wrote:
> On 10/18/07, Don Stewart <[EMAIL PROTECTED]> wrote:
> >
> > Please drop by the irc channel! enthusiasm is always welcome there, and
> > we're pretty much all obsessed too!
>
> Maybe that's not The Right Thing(TM) to ask, but anyway. :)
On 10/18/07, Don Stewart <[EMAIL PROTECTED]> wrote:
>
> Please drop by the irc channel! enthusiasm is always welcome there, and
> we're pretty much all obsessed too!
Maybe that's not The Right Thing(TM) to ask, but anyway. :)
My access the world outside the office's LAN is limited to ports 80 and
Maybe I'm seeing things but from what I remember packages that used to
have links to Haddock documentation in their exported modules list no
longer has. It's a super useful feature! What happened to those
packages?
-- Johan
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Ryan Ingram wrote:
On 10/18/07, Janis Voigtlaender <[EMAIL PROTECTED]> wrote:
Yes, but that's a problem of the Arrow library writer, not of GHC. The
compiler will never check a RULE.
I'm going to disagree a bit here; it's not the problem of the Arrow
library writer at all, it's the problem o
On Fri, Oct 19, 2007 at 02:09:01 +1000, Matthew Brecknell wrote:
>Magnus Therning:
>> Just out of curiosity, how would I go about finding this myself?
>> (Ideally it'd be an answer other than "read the source for the libraries
>> you are using". :-)
>
>Well, I can at least try to expand a little on
Ha, well spotted! GHC's "RULE" mechanism is specifically designed to allow
library authors to add domain specific optimisations. Just as a library author
can write a buggy implementation of 'reverse', so s/he can write a buggy
optimisation rule.
So I guess it's up to the authors and maintaine
On 10/18/07, Janis Voigtlaender <[EMAIL PROTECTED]> wrote:
> Yes, but that's a problem of the Arrow library writer, not of GHC. The
> compiler will never check a RULE.
I'm going to disagree a bit here; it's not the problem of the Arrow
library writer at all, it's the problem of the implementor of
That's pretty cool. If you are not yet aware of it, you might want to
compare this with the EasyCheck library for Curry. They directly use
functional logic programming for test generation, where you use
exceptions for simulating logical variables. Here are some slides of a
talk I heard recently:
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