to pdf and other formats this might be useful:
http://muitovar.com/gtk2hs/app1.html (There's a Spanish translation
too.) However, this tutorial is a few years old now, and I don't know if
it's still up to date for the later Gtk2Hs versions
That's interesting, writing a DSL that compiles to C. I've actually
inerviewed Gerard Holzamann twice, the first time when he received the
ACM Software System Award in 2002 [1] and in 2008 after he moved to JPL
[2]. What they use to test distributed software is the Process Meta
Language (Promela) w
8047
I think this is interesting even to those who are not looking for a job
right now, since it shows the current mind-set regarding Haskell, at a
major and leading IT company.
Best Regards,
Hans van Thiel
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amongst all
the advantages and disadvantages, maintainability is surely a strength!
Anyway, for anyone who's interested in the application, see
http://muitovar.com/emp/emp_get.php
and related links. Yes, unfortunately the demo is not in Haskell...
Regards,
Hans van Thiel
s with the results. All comments most
welcome...
Emping is a (prototype) interactive tool for the discovery and analysis
of (universal, not statistical) predictive rules in tables of nominal
data.
Best Regards,
Hans van Thiel
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Ha
right?
(.) ::(b -> c) -> (a -> b) -> (a -> c)
Many thanks, also to the others who've replied. I've wondered about
(=<<) usage for a long time too, and this is all very illuminating. I'll
work this through and put it in my monad tutorial, if
its own name, it must have some practical use. Do you, or anybody else,
have some pointers?
Best Regards,
Hans van Thiel
>
> - Jake
>
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tion, I think.
Best Regards,
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I'll look at my code
again. Many thanks for your helpful reply!
Best Regards,
Hans van Thiel
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== 0) gr
Many thanks,
Hans van Thiel
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icism.
>
> [1] http://ertes.de/articles/monads.html
>
>
> Greets,
> Ertugrul.
>
Looks pretty good to me! Could you add a link in the Haskell tutorials
section?
Best Regards,
Hans van Thiel
>
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On Sat, 2008-12-27 at 11:54 -0600, Jake McArthur wrote:
> Hans van Thiel wrote:
> > However, some functions in Haskell may have side effects, like printing
> > something on the screen, updating a database, or producing a random
> > number. These functions are called 'act
s, and
the 'actions'.
If I guess correctly, then the general statement 'monads are for
actions' is wrong. It should be something like, 'monadic composition is
a useful method of generalization, which, by the way, allows you to
isolate side effects in a controlled manner'
types of c or
str are pretty clear, aren't they?
Just something that's been puzzling me for some time now...thanks.
Regards,
Hans van Thiel
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can write asserts, test liveness and you can
even check claims in LTL (linear temporal logic) about execution paths.
It's all open source and free. 'The Spin Model Checker', by Gerard
Holzmann, is the reference, but there are several other books about Spin
and its principles.
Best Regards,
Hans van Thiel
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some, uses or can use
a GUI at this point in time?
Secondly, has Gtk2Hs compatibility been tested with GHC 6.10? In the
past there have sometimes been problems with new GHC releases and
Gtk2Hs. These have always been addressed, but it usually took a few
months..
Cheers,
Hans van Thiel
[snip]
you need a user guide (or not, in the rare
case it's self documenting).
I feel it's a mistake not to distinguish between those two, in
particular when the number of packages gets very large, as is now
happening.
Secondly, some major libraries are not on Hackage (yet), e.g. Gtk2Hs.
Regards,
Hans van Thiel
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[snip]
>
> Most probably you are confusing type and data constructor. This is a common
> error and a hurdle I remember falling over more than once. It is due to the
> fact that in Haskell both are in completely separate name spaces,
> nevertheless both use capitalized names. Thus people often use
On Mon, 2008-08-25 at 00:33 +0200, Ben Franksen wrote:
> Hans van Thiel wrote:
> > so 'The Greenhorn's Guide to becoming a Monad Cowboy' is on
> > http://www.muitovar.com/monad/moncow.xhtml
>
> Forgot to say: nicely written!
>
> Some more comments:
Hello All,
I'm proud to announce the first monad tutorial of the new season. It's
under the Wiki permissive licence, but the web page has some clip art,
so 'The Greenhorn's Guide to becoming a Monad Cowboy' is on
http://www.muitovar.com/monad/moncow.xhtml
Best
Let's not start now.
>
> This is a civilized mailing list. Either comment on the nice gentlemen's
> PHP closure proposal from a language point of view, or don't say anything.
>
> Jules
Hear, hear...
Hans van Thiel
>
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Regards,
Hans van Thiel
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[snip]
> > The current a priori check, which said there were no fatal errors, while the
> > a posteriori check failed, is misleading. Wouldn't it be better to warn
> > potential
> > uploaders that this first check is not complete?
>
> I'm not sure I see what you're getting at. We can't do a full
only 0.9.11 (until a few months ago, at least). So, if an uploader knows such
dependencies, how to express them?
Thanks in advance,
Hans van Thiel
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few screenshots.
Thank you all,
Hans van Thiel
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All of which would
be useful to the Haskell community, IMO, but that's a personal view.
Best Regards,
Hans van Thiel
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ry. To get an impression see:
http://j-van-thiel.speedlinq.nl/emp/empug.html
The compiled binary for Linux, with documentation, can also be
downloaded directly from my web site.
Thank you,
Hans van Thiel
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short while in 1999 and they had two Russian software
engineers there, one from St. Petersburg and one from Wladiwostok, both
female and under 25 years of age. They programmed in C and were highly
respected by their managers and colleagues! So, there are at least
counterexamples :-)
Regards,
Hans
nq.nl/glade/es-index.html
The translator of both texts prefers to be known as Laszlo Keuschnig. In
case anyone wonders, this is not me, though I wish..
Best Regards,
Hans van Thiel
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On Wed, 2007-12-12 at 16:27 +0100, Hans van Thiel wrote:
> [snip]
> >
> > I fear those people can do vast amounts of damage. :(
> >
> > When inept programming yields the wrong result, it is clear (even to the
> > inept) that the program is bad.
> >
>
On Tue, 2007-12-11 at 16:56 +0100, Wolfgang Jeltsch wrote:
> Am Dienstag, 11. Dezember 2007 14:46 schrieb Hans van Thiel:
> > On Mon, 2007-12-10 at 20:00 +0100, Henning Thielemann wrote:
> > [snip]
> >
> > > I raise my question once again: Must Haskell's tutor
is.
And the purpose of a tutorial is not to make the writer look smart and
important, but to ease things for the reader. I wouldn't want to exclude
the scurrilous unwashed from the Haskell experience, this close to
Christmas, too. :-)
Regards,
Hans van Thiel
>
__
Needless to say, please don't hesitate to comment and report
errors.
Regards,
Hans van Thiel
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e Java Rule Engine (I believe JSR 94) and in
particular Jess?
http://herzberg.ca.sandia.gov/
I have no experience with it myself, though, just heard of it.
Regards,
Hans van Thiel
> Any link to tools or methods that could help me in that task would be
> greatly appreciated. I already sear
On Sat, 2007-11-10 at 11:14 -0800, David Roundy wrote:
> On Sat, Nov 10, 2007 at 06:56:23PM +0100, Hans van Thiel wrote:
> > Thanks to all who've replied; Carl's explanation in particular was very
> > interesting. So the precision, suggested by the many decimals in t
ns, you should not
use sin for smaller values. In all cases the actual precision of sin
appears to be 4 to 5 decimals, and results should be rounded to that
before using them. Now I'm wondering about cos, tan and also the
inverses, asin etc. :-)
Regards,
Hans van Thiel
Hugs> sin (1.000 * pi)
On Fri, 2007-11-09 at 14:30 -0500, Brent Yorgey wrote:
>
> On Nov 9, 2007 2:08 PM, Hans van Thiel <[EMAIL PROTECTED]> wrote:
> Hello All,
> Can anybody explain the results for 1.0, 2.0 and 3.0 times pi
> below?
> GHCi yields the same r
Hello All,
Can anybody explain the results for 1.0, 2.0 and 3.0 times pi below?
GHCi yields the same results. I did search the Haskell report and my
text books, but to no avail. Thanks in advance,
Hans van Thiel
Hugs> sin (0.0 * pi)
0.0
Hugs> sin (0.5 * pi)
1.0
Hugs> sin
Prolog. See the
link for features, but http://www.cs.bris.ac.uk/~bowers/goedel.html
was last updated in 1995. Does anybody know more?
Hans van Thiel
[snip]
>
> To Jerzy's point -- I strongly believe that learning a language like
> Prolog is a good idea for two reasons -- first, it adds a
does not cover everything. The
same applies to the port. Moreover, advanced widgets like Tree List are
large and complicated and will not be treated at all.
Note 3: This tutorial, and in particular the 'Getting Started' chapter,
replaces the old 'Getting Started' page, whi
oyed other than in open source, but
that fact is not being advertised in the marketing.
Maintainability should be excellent in Haskell,
due to the fine grained modularity without side effects.
Best Regards,
Hans van Thiel
>
>
> As I wrote above, I'm quite new to Haskell. Thus
completion
time is highly dependent on how well the data is structured.
Obviously, much has still to be done.
More info, for those who are interested, on
http://j-van-thiel.speedlinq.nl/emp/empug.html
Thank you,
Hans van Thiel
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On Fri, 2007-06-29 at 19:35 +0200, Thomas Schilling wrote:
> On 27 jun 2007, at 18.41, Hans van Thiel wrote:
>
> > [snip]
> >
> > Thanks, Apfelmus, for the references. Guess I'll start there, then.
> > And
> > thanks, Chris, for the info and code. Rea
[snip]
Thanks, Apfelmus, for the references. Guess I'll start there, then. And
thanks, Chris, for the info and code. Read only 'up pointers' could be
what is needed. But before going on, I want first to get more
confortable with programming with trees. It's all very well to say
they're easy to rol
ow expensive this would
be in Haskell, or if it's necessary at all.
Many thanks for your help,
Hans van Thiel
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; work?
It would be a nice feature, if authors could remove obsolete packages
from HackageDB as well as add new versions. It would also be helpful to
see download statistics. If something is much in demand, this would
probably be an incentive to update it more often..
Regards,
Hans van Thiel
> Che
ave a lot of potential.
What I've seen of it, before it crashes, looks very nice.
Regards,
Hans van Thiel
> In fact part of the project seems to be to
> allow the development of eclipse plugins written in haskell, which
> could allow the possibility of integrating some of the tools lis
re you can learn 'serious' Haskell you'll have
to learn basic Haskell. I'm sure it is unintentional, but avoid any
impression of superiority. Writing a good text book is very hard and
very time consuming, and succesful communication with an audience is a
separate skill. How about &#
as ever considered such dependencies.
Regards,
Hans van Thiel
>
> * Hans van Thiel <[EMAIL PROTECTED]> [070521 05:45]:
> > Hello All,
> >
> > Version 0.2 of Emping, a utility to derive heuristic rules from a table
> > of nominal data, is available. In additio
Thanks for the help! Strangely, I just now received your messages from
April 28, hence the late reply...
Hans van Thiel
On Sat, 2007-04-28 at 18:09 +0200, Henning Thielemann wrote:
> On Sat, 28 Apr 2007, Hans van Thiel wrote:
>
> > Hello All,
> >
> > The standard fun
the HackageDB.
Thanks,
Hans van Thiel
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On Sat, 2007-05-19 at 15:30 +0100, David House wrote:
> On 19/05/07, Hans van Thiel <[EMAIL PROTECTED]> wrote:
> > causes no problems in Hugs (-98 flag) but compiling with GHC produces:
>
> There's the solution to your problem: type synonym instances aren't
>
ynonym, but can't
get it right. (I'm using the ghc 6.6.1 Fedora Core 6 package).
Many thanks in advance!
Hans van Thiel
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(x,y) = partition ((head ls) `eq`) ls
example>
partitionBy (\x y -> (last x) == (last y)) ["abc","bd","bdc","abd"]
result>
[["abc","bdc"],["bd","abd"]]
Of course, a
-> [[a]]
partitionBy eq [] = []
partitionBy eq ls =
(fst x):(partitionBy eq (snd x)) where
x = partition1 eq ls
Regards,
Hans van Thiel
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On Sat, 2007-04-28 at 15:08 +0100, Neil Mitchell wrote:
> Hi Hans,
>
> > > The standard function groupBy of List.hs doesn't work as I expect in
> > > this case:
> > >
> > > groupBy (\x y -> (last x) == (last y)) ["abc", "bd","cac"]
> >
> > You are doing something wrong. groupBy is specified to ne
On Sat, 2007-04-28 at 06:45 -0700, Stefan O'Rear wrote:
> On Sat, Apr 28, 2007 at 03:49:44PM +0200, Hans van Thiel wrote:
> > Hello All,
> >
> > The standard function groupBy of List.hs doesn't work as I expect in
> > this case:
> >
> > groupBy
> [[a]]
groupBy _ [] = []
groupBy eq (x:xs) = (x:ys) : groupBy eq zs
where (ys,zs) = span (eq x) xs
Thanks,
Hans van Thiel
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e monadic replacements, and
so on.
4) there is a very helpful and knowledgeable community.
A major disadvantage of Haskell is the lack of books, especially with
regard to intermediate level programming and the libraries.
Documentation that is available varies in quality and is, in general,
fragmented.
Best Regards,
Hans van Thiel
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ut I'm leaving it at that, because (1) I'm assuming the package
itself is OK and (2) it's a standalone utility so maybe Cabal is
overkill anyway (though it's nice how Cabal forces a structure). Just
compiling the source modules is, probably, the preferr
rough
Multimedia
. . .
We recommend: Cooking Entrees With the Micheff Sisters: A Vegan
Vegetarian
Cookbook
by Brenda Micheff Walsh
Recommended because you purchased or rated:
* Purely Functional Data Structures
To be fair, other recommendations were more traditional ...:)
Hans van Thiel
s
On Tue, 2007-03-13 at 00:47 -0400, Albert Y. C. Lai wrote:
> Hans van Thiel wrote:
> > sequence :: Monad m => [m a] -> m [a]
> >
> > You write:
> > The >>= used by sequence is the same >>= in the MyState monad,
> > since you instantiate m to MySta
Albert,
Thanks very much for your explanation. I see now that I confused the
state function with the f, but it's still not quite clear.
data MyState a b = MyStateC ([a] -> ([a], b))
This defines an algebraic data type (...why is it called algebraic?)
with two type variables and a unary construc
the list xs, from left to right,
and returns a list of the "contents" of these monads, placing this list
in a monad of the same type. Note, that "evaluating" can be interpreted
as "performing an action", for example in the case of print."
It looks to me as if sequence works here because values of MyState are
themselves functions, but how?
Many thanks for any pointers and clarification!
Hans van Thiel
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I. On Sun, 2007-01-21 at 11:20 -0800, Stefan O'Rear wrote:
> On Sun, Jan 21, 2007 at 08:00:53PM +0100, Hans van Thiel wrote:
> > On Sun, 2007-01-21 at 09:42 -0800, Stefan O'Rear wrote:
> > > This is the closest you'll get with GHC extensions:
> > >
&
On Sun, 2007-01-21 at 09:42 -0800, Stefan O'Rear wrote:
> On Sun, Jan 21, 2007 at 06:21:34PM +0100, Hans van Thiel wrote:
> > class (Num a, Monoid a) => NumMon a where
> >e = 0
> >add x y = x + y
>
> > What am I doing wrong? Many thanks in advance.
ied instance definitions of NumMon (leaving out 'where' and
what's next in the class declaration) and get similar messages.
The definition of NumMon by itself, just the first line, is accepted by
Hugs and GHCi both.
What am I doing wrong? Many thanks in advance.
Hans van Thiel
On Mon, 2007-01-08 at 16:11 -0200, Alex Queiroz wrote:
> Hallo,
>
> On 1/8/07, Hans van Thiel <[EMAIL PROTECTED]> wrote:
> > Hello All,
> >
> > The beta of the 'Gtk2Hs:Getting Started' short tutorial for beginners,
> > Haskell GUI for Dummies,
troduces the api and explains how to use it, refers to the Glade
tutorials, gives an example of widget layout, and ends with some general
pointers.
It should take no more than 2,3 hours of the user's time.
All feedback very welcome.
Regards,
Hans van Thiel
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guages who are interested could use these and check out the Haskell
Gtk2Hs listings later.
Thanks,
Hans van Thiel
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tk2Hs and covers the
basics of Glade and how to access a .glade file and widgets in Gtk2Hs.
Estimated learning time: 2 hours.
Thanks to Duncan Coutts and Eddy Ahmed for their help and cooperation.
The tutorial will be made available on the Gtk2Hs web site and on Eddy's
homepage as well.
ugs
doesn't.
>
Ah, so that's it! Thanks, all.
Hans van Thiel
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On Tue, Oct 24, 2006 at 06:14:14PM +0200, Hans van Thiel wrote:
> I have a similar question. When I use getChar with Hugs the
newline
> (caused by pressing 'Enter') seems to be carried over into
the next
> call of main, where it is treate
No, it happens with Hugs on Fedora Core 5 (the fc5 Hugs package), not
WinHugs.
Thanks,
Hans
On Tue, 2006-10-24 at 17:27 +0100, Neil Mitchell wrote:
> Hi
>
> > I have a similar question. When I use getChar with Hugs the newline
> > (caused by pressing 'Enter') seems to be carried over into the
right away. I suppose the solution offered here:
hSetBuffering stdin NoBuffering
will have the desired effect, but is there another way?
Thanks,
Hans van Thiel
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s tutorial to Haskell Gtk2Hs, but meanwhile I'd like to submit my
separate concept (attached) for comments.
Thanks,
Hans van Thiel
Gtk2HsGlade.odt
Description: application/vnd.oasis.opendocument.text
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well defined chain where each action becomes unique, even
though names (like getLine) on the different positions are the same.
But again, the monadic computation is still a function.
I'd appreciate your comments.
Regards,
Hans van Thiel
--
Don't worry, be happy, learn Haskell.
_
C and how to use them. At the moment I'm reading the book again,
from the beginning, and I'm seeing several things much better than I did
the first time(s).
Hope this helps,
Hans van Thiel
--
Don't worry, be happy, learn Haskell.
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From:
Hans van Thiel
<[EMAIL PROTECTED]>
Reply-To:
[EMAIL PROTECTED]
To:
Johan Tibell
<[EMAIL PROTECTED]>
Subject:
Re: [Haskell-cafe] Re:
ce, I think.
That is, assuming 'mainstream' is the goal, of course.
Regards,
Hans van Thiel
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my question (while introducing myself to
the Cafe at the same time).
Why hasn't Haskell made it into the business world (yet), after being
available for 15 years, or is this the wrong question?
Many thanks for your comments,
Hans van Thiel
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