PhD/PostDoc opening in programming techniques and technologies in the
Software Languages Team [1] in Koblenz.
Applicants can safely assume that functional programming plays a huge
role in this.
The application deadline is 31 Aug.
A German description of formalities is available [2].
One essenti
Disclaimer: this is an Xmas gift as opposed to serious stuff.
http://professor-fish.blogspot.com/2009/12/major-breakthrough-in-image-processing.html
Greetings,
Ralf
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as been adopted from Stratego). All in all, this more like "try
and catch" or "exception handling" rather than "calculations returning
multiple values".
Ralf
--
Ralf Laemmel
VU & CWI, Amsterdam, The Netherlands
http://www.cs.vu.nl/~ralf/
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Timely question. :-)
GHC supports lexically scoped type variables.
And this support has just been _extended_ to be readily useful for you
(see discussion on the ghc list just a few days back).
With GHC CVS HEAD the following program works fine.
(Note that I removed the inner Num constraint.)
{-# OP
Major apologies for this repeated plug for HList.
Anyway, HLists [1] are *exactly* designed for this sort of problem.
Well, one can also use existential quantification + bounded polymorphism;
with the shapes benchmark providing a good example [2]. The trade-offs are
explored a little bit on the OOH
Hi,
foo _ = undefined
works fine.
Otherwise the poor little "a" has no chance to get disambiguated.
... Ambiguous type variable `a' in the top-level constraint ...
Ralf
Stefan Holdermans wrote:
Hi,
Just out of curiosity (I cannot come up with a practical example):
Why doesn't the following piece
Adam Zachary Wyner wrote:
Question -- is this all there is to the issue, or is there something more?
Apologies in advance for not understanding the math better here.
You can compare functions in a pointwise fashion,
which does not work (other than approximatively) for infinite domains.
This is the
Instance selection and thereby overlapping resolution
is *independent* of constraints. It is defined to be purely
syntactical in terms of instance heads. See the HList paper
for some weird examples.
Ralf
Graham Klyne wrote:
The reported overlapping instance is [Char], which I take to be
derived fr
Vitor,
That's amazing!!! Your question is very timely! :-)
You know ... someone just challenged me with this question,
and I added the corresponding function to the boilerplate testsuite.
However, it is much more typeful than you propose.
I call it the "typeful reflection benchmark".
http://www.cs.
Matthew Roberts wrote:
I am looking for a functional programming summer school in the next 12
months. I realise there was one August this year, does anyone know of
any others coming up?
July 4-8 2005 will be an international summer school on
generative and transformational techniques in software
Graham Klyne wrote:
> At 22:17 13/10/04 +0200, Ralf Laemmel wrote:
>
>> ... We reconstruct OCaml's tutorial in Haskell ,,,
>
>
> I think that's interesting as a theoretical exercise, but I don't
currently
> see myself using that framework in practice
[EMAIL PROTECTED] wrote:
Some people say that ocaml's object system is kinda useless. The best
support I hear so far was:"it does not hurt"
Why do you (or do these people) think having all the OO idioms of OCaml
(see OCamls OO tutorial) is useless? Or do you mean too baroque? If not,
what's
missin
John Goerzen wrote:
One of the best features of OO programming is that of inheritance.
...
Oleg, Keean and me have lying around a draft that adds to this
discussion. We reconstruct OCaml's tutorial in Haskell
The short paper version is online and under consideration for FOOL:
http://homepages.cwi.n
-> String
xsdNS :: a -> String
...but rather define a generic function, this time is nothing but
a type case of type
forall x. Typeable x => x -> Maybe (String, String)
Hope it helps.
Conclusion: don't use classes, rather use generic functions.
Ralf
Simon David Foster wrote:
On T
{-# OPTIONS -fglasgow-exts #-}
{-
Regarding Keean's posting ...
I wonder whether perhaps a more basic step is to understand
how type-changing monadic computations can be understood.
By this I mean, that the effects model by the monad can change
their type as part of the computation. Such a monad
Hi Graham,
Graham Klyne wrote:
It's been a while since I looked at the "boilerplate" work, but
looking at your code I think it depends on gmapQ of the polymorphic
value to be converted. Does your generic Haskell processor generate
this automagically?
One needs Data and Typeable instances which
Graham Klyne wrote:
If I have a polymorphic algebraic type (T a) with several type
constructors, only one of which actually references the type
parameter, is there any way to express type conversion for the
type-parameter-independent constructors without actually mentioning
all the constructors
Mike Aizatsky wrote:
It's quite good. It reminds me the quirks Alexandrescu does in his "Modern
C++ Design" or here
http://osl.iu.edu/~tveldhui/papers/Template-Metaprograms/meta-art.html .
Since type system allows implementation of natural arithmetic, do you know,
is it Turing-complete?
Yes, C. McB
Hi Mike,
Let's redirect to Haskell cafe.
http://www.mail-archive.com/glasgow-haskell-users%40haskell.org/msg06288.html
http://www.mail-archive.com/glasgow-haskell-users%40haskell.org/msg06289.html
thanks for your time to look into the HList paper.
1. It looks like your HList is basically a "sugariz
Brandon Michael Moore wrote:
Great. But I can't build from the source: I'm getting errors about a
missing config.h.in in mk. I'm just trying autoconf, comfigure. I'll look
closer over the weekend.
Use the following (more specifically autoREconf).
The GHC build guide is behind.
cvs -d cvs.haskel
Continuing Keith's self-reply ...
the Music type involves types
other than Music; so it is fair to say that
ultimately you would need generalised folds
extended to the case of *systems* of datatypes
(cf. "Dealing with large bananas"). Imagine
for example getPitches :: Music -> [Pitch].
Even if a
Hi Mark,
The boilerplate style of generic programming [1] should be of help here.
For example, here you can see how to do a normal read and show:
http://cvs.haskell.org/cgi-bin/cvsweb.cgi/fptools/libraries/base/Data/Generics/Text.hs?only_with_tag=MAIN
We are also using this style to do decode and
mally, technically)?
Ralf
--
Ralf Laemmel
VU & CWI, Amsterdam, The Netherlands
http://www.cs.vu.nl/~ralf/
http://www.cwi.nl/~ralf/
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