[cwn] Attn: Development Editor, Latest Caml Weekly News
Alan Schmitt
alan.schmitt at polytechnique.org
Tue Jul 4 01:19:32 PDT 2006
Hello,
Here is the latest Caml Weekly News, for the week of June 27 to July
04, 2006.
My son, Augustin, turns 5 today. Happy Birthday Augustin!
1) Esterel Technologies is looking for a Caml Engineer
2) Marshalling data format deteriorates compressibility
3) RASCL's A Simple Configuration Language
4) XStream: streaming XML transformation
5) Numerix-0.22
6) Bindings for SDL and OpenGL 2.0 plus extensions
7) Which development framework for web application in OCaml?
8) Question on Variant Types
9) Type from local module would escape its scope?
10) Camomile 0.6.6
11) Sentence Segmenter
========================================================================
1) Esterel Technologies is looking for a Caml Engineer
------------------------------------------------------------------------
** Amandine ROY announced:
I am Amandine ROY, HR Manager of Esterel Technologies (international
company of 140 employees).
<http://www.esterel-technologies.com>
We develop software solutions for critical embedded software
development that enable to capture, communicate and automatically
implement completely unambiguous software specifications.
Actually, I am looking for one engineer, within our R&D Department,
who will participate in the development of a tool that make
structural code coverage (MCDC) for CAML programs.
This job is located in Elancout (near Paris) or in Toulouse.
You will find the job description on our web site:
<http://www.esterel-technologies.com/company/jobs/france-elancourt.html>
If you or one of your connexions is interested , do not hesitate to
contact me.
Best regards,
Amandine ROY
Human Resources Manager
amandine.roy at esterel-technologies.com
ESTEREL TECHNOLOGIES
Phone: +33 1 30 68 61 74 - Fax: +33 1 30 68 61 61
<http://www.esterel-technologies.com>
========================================================================
2) Marshalling data format deteriorates compressibility
Archive: <http://groups.google.com/group/fa.caml/browse_thread/thread/
2a504af427dee5f2/fa72716dc7be20b3#fa72716dc7be20b3>
------------------------------------------------------------------------
** Markus Mottl announced:
I have just finished (and attached) a patch for the latest CVS-release
of OCaml, which adds a new marshalling flag. This flag generates a
different marshalling format, which uses absolute addresses to refer
to shared values. This fixes the problem of bad compressibility of
marshalled OCaml data. See the patch header for more information.
Since the patch is quite small and does not break any existing code,
we'd be very grateful if it could be made part of the next
OCaml-release. I'll also enter the patch into the OCaml bugtracker so
that people running into the same problem can find it there, too.
(See the archive for the attachment.)
========================================================================
3) RASCL's A Simple Configuration Language
Archive: <http://groups.google.com/group/fa.caml/browse_thread/thread/
05c8331ea6f3d74e/5519216d4774a054#5519216d4774a054>
------------------------------------------------------------------------
** Matt Gushee announced:
Here's yet another configuration language--with an OCaml library to
process it, of course.
RASCL came into being after I investigated the Config_file library and
found it overly complex--which may say more about me than about the
library. But at any rate, RASCL, the language, and Rascl, the OCaml
library attempt to be about as simple as possible for both users and
developers, at the expense of some generality.
Here are some of the main features:
* A RASCL file may be just a sequence of keys and values, or it may
be arbitrarily nested.
* Values may be strings, integers, floats, booleans, or lists thereof.
* No OCaml-specific types supported (that's a feature, not a bug ;-)
* Strings need not be quoted unless they contain special characters
or would otherwise be parsed as another type.
* Two interfaces for accessing configs:
- Dict module
- Object system, with a CamlP4 preprocessor to generate objects
and sample config files
BTW, I have attempted to provide thorough documentation for the language
RASCL--in case anyone wants to implement it for other programming
languages. However, I don't have a lot of experience writing language
specifications, and there are probably some errors and ambiguities. I'd
appreciate feedback from any interested and knowledgeable parties.
RASCL and Rascl may be found at: <http://matt.gushee.net/rascl/>
========================================================================
4) XStream: streaming XML transformation
Archive: <http://groups.google.com/group/fa.caml/browse_thread/thread/
8a2433ad0dcea835/9289436eccb63c8d#9289436eccb63c8d>
------------------------------------------------------------------------
** Alain Frisch announced:
This is to announce the first public release of XStream, a simple
programming language for XML. Transformations written in XStream are
compiled into efficient XML stream processors: the output is computed
and produced while the input is being parsed, which makes it possible to
run some transformations on very big XML documents which could not even
fit in memory.
Though XStream is mostly intended as a back-end for higher-level
languages, it is also possible to use it directly. The language
features ML-like pattern matching and higher-order functions, but no
types.
Here's how XStream relates to OCaml: the compiler is written in OCaml
and uses OCaml as a back-end to produce efficient native code. Moreover,
XStream programs can embed OCaml code and manipulate OCaml values
(useful to deal with non-XML data).
Web-site: <http://yquem.inria.fr/~frisch/xstream>
** David MENTRE asked and Alain Frisch answered:
> It seems obvious but I want to be sure: can XStream generated code be
> embedded in OCaml programs (native and bytecode)?
Currently, XStream generates only a fully functional executable
transformaion which reads its input from an XML file and send its output
to the standard output.
It would be quite simple to have it generate an OCaml module which
exports a ``filter'' function (a transformer of XML event streams) if
there is some demand for such a feature.
> How XStream compares to OCamlDuce?
OCamlDuce is intended to write large OCaml applications which need to
manipulate XML data. XStream is really meant as an XML transformation
tool. In particular, to achieve efficient streaming, XStream keeps
control over the evaluation of the transformation as a whole. OCamlDuce,
instead, relies on the regular OCaml evaluation mechanism.
> So XStream cannot be used as a replacement to
> OCamlDuce. Is it correct?
Yes it is.
** Richard Jones asked and Alain Frisch answered:
> I downloaded the tarball and looked at
> the examples and I can't tell: can XStream transform an XML file into
> something else?
> In particular we have a requirement to convert a huge XML file into
> tabular CSV data on the fly (while the XML is being downloaded). The
> XML file just consists of a very large number of <row>...</row>
> records.
That's possible with XStream: text is just a special case of XML.
For instance, the following script extracts the stream of text from the
input XML stream.
main(_[x1] x2) -> concat(main(x1),main(x2))
main(%s x) -> %s main(x)
main(()) -> ()
========================================================================
5) Numerix-0.22
Archive: <http://groups.google.com/group/fa.caml/browse_thread/thread/
8ea6dc93783aa80a/d9753f86a3239c92#d9753f86a3239c92>
------------------------------------------------------------------------
** Michel Quercia announced:
It is my pleasure to announce the release of the new version of the
Numerix library (version 0.22).
Numerix is a multiprecision library providing operations on integers of
arbitrary length; it is interfaced with the following programming
languages : Caml-light, Objective-Caml, C and Pascal. Concerning the
speed, it is as fast as the GNU-MP library, and may even be faster
(depending on the architecture and the size of the numbers to be
computed
).
This new version includes, among other improvements :
-- assembly code for the x86-64, the Dec-alpha, and the Power-PC-32
processors.
-- the possibility to compile Numerix on Windows Computers, with the
help of one of the Cygwin or Msys environnements.
Download :
<http://pauillac.inria.fr/~quercia/cdrom/bibs/numerix.tar.gz>
Documentation :
<http://pauillac.inria.fr/~quercia/cdrom/bibs/numerix-eng.pdf>
========================================================================
6) Bindings for SDL and OpenGL 2.0 plus extensions
Archive: <http://groups.google.com/group/fa.caml/browse_thread/thread/
0734582cf1ab0655/17080096249f42c1#17080096249f42c1>
------------------------------------------------------------------------
** Elliott Oti announced:
In the interests of reinventing the wheel where possible, I wrote OCaml
bindings for the SDL libraries and OpenGL libraries over a couple of
weekends.
The (automatically generated) OpenGL bindings cover OpenGL 1.1, 1.2,
1.3, 1.4, 1.5, 2.0 and most current non-platform-specific extensions.
There are no dependencies whatsoever: the system opengl shared library
is loaded dynamically, and the functions are called dynamically, so
there is no need to link against import libraries.
The SDL bindings are fairly but not wholly complete; they are
hand-written and functions are bound on an as-needed-by me basis. They
are only dependent on the SDL main library and not on the mixer, ttf or
image libraries. Because I wanted to have basic sound capabilities, the
SDL_Audio modules are implemented, along with extra functions for
panning and pitch shifting audio buffers.
In addition there are functions written in OCaml to load uncompressed
and RLE-encoded TGA files, scale bitmaps with different filters
(currently, only box, tent and lanczos3 filters are implemented),
generate mip-maps suitable for usage in OpenGL, and a complete port
from C to OCaml of the SFont bitmapped text library.
This is very much a work-in-progress, and is currently at version 0.1.
It has been tested on Windows 2000, Windows XP, and Ubuntu Linux on
AMD64. It compiles as-is with the mingw port of OCaml 3.09 and on
Linux. It has not been tested on any other platform. There are around
20 example files. SDLCaml and GLCaml are being written primarily for my
personal needs but are being released in the hope that someone finds
them useful. Feedback is welcome.
SDLCaml and GLCaml are released under the LGPL, version 2.
Main site: <http://www.elliottoti.com/index.php?p=15>
Gzipped source tarball:
<http://www.elliottoti.com/code/gfx/glcaml.0.1.tar.gz>
Documentation: <http://www.elliottoti.com/code/gfx/doc>
========================================================================
7) Which development framework for web application in OCaml?
Archive: <http://groups.google.com/group/fa.caml/browse_thread/thread/
47e3244b5bd1c2d1/ed3e35a9815c49e2#ed3e35a9815c49e2>
------------------------------------------------------------------------
** A week ago, David MENTRE asked:
For my demexp server, I'm considering the development of a web
interface, accessible from a simple web browser. I have standard
requirements (html forms) as well as "advanced" ones (would like to
support AJAX-like things, navigation in tree data structures, etc.).
Which development frameworks are available to do such things in OCaml?
I'm looking for frameworks under a license compatible with GNU GPL.
Right now, I know about:
- WDialog
- XCaml
For low level stuff (basic CGI interface), there is also OCamlNet.
I've made some experiments with WDialog but I'm not entirely convinced
by its approach of separating interface description from event
handling code. Moreover it lacks some features that would be useful
for us : i18n support (even if, thanks to Gerd, a preliminary code is
available in CVS tree), advanced widgets (tree structures), AJAX
support, etc.
What other people are using to do web stuff? Is everybody using PHP? ;-)
Any recommandation on building such complex web interface with
available OCaml software?
Best regards,
david
PS : My current demexp server is an autonomous Unix daemon, written in
OCaml, accessible through ONC RPC calls over a TCP socket. Until know,
I have made a simple CGI that access the demexp server. But I'm
considering merging the server part with the web part. Has somebody
some knowledge on the design of web architecture and recommendation or
pointer to relevant litterature?
** Editor's note:
There have been many new replies to this thread. You may read them at
the
archive link above.
========================================================================
8) Question on Variant Types
Archive: <http://groups.google.com/group/fa.caml/browse_thread/thread/
88aedcd1af43b291/d35b3a582cbf3294#d35b3a582cbf3294>
------------------------------------------------------------------------
** Jonathan Roewen asked and Chris King answered:
> I seem to be running into the problem of not being able to coerce
> polymorphic abstract types that use variants.
>
> Eg:
>
> type 'a t;;
> type x = [ `Foo ];;
> type y = [ `Bar | x ];;
> let widen x = (x : x t :> y t);;
> Gives:
> Type x t is not a subtype of type y t
> Type x = [ `Foo ] is not compatible with type y = [ `Bar | `Foo ]
> The first variant type does not allow tag(s) `Bar
> Yet the above approach works fine for non-abstract types.
You need to explicitly specify the variance of 'a t:
type +'a t;;
This tells the type system that t is covariant with respect to 'a: if
x is a subtype of y, then x t is a subtype of y t. Not all compound
types share this property (most notably, mutable structures are
invariant and function arguments are contravariant) so O'Caml must
assume all abstract types to be invariant unless it's told otherwise.
========================================================================
9) Type from local module would escape its scope?
Archive: <http://groups.google.com/group/fa.caml/browse_thread/thread/
ccbcaf21b44fed78/3c71209f4969c4dc#3c71209f4969c4dc>
------------------------------------------------------------------------
** Bruno De Fraine asked and Virgile Prevosto answered:
> I don't quite understand this behavior regarding local modules (in
> OCaml 3.09.2):
>
> The following is accepted:
>
> module type FOO =
> sig
> type t
> val value : t
> end ;;
>
> let foo () =
> let module Foo : FOO =
> struct
> type t = int
> let value = 1
> end in
> ignore Foo.value
> ;;
>
> While the following is rejected:
>
> let foo (ignore: 'a -> unit) =
> let module Foo : FOO =
> struct
> type t = int
> let value = 1
> end in
> ignore Foo.value
> ;;
>
> With an error on the expression "Foo.value" stating that "The type
> constructor Foo.t would escape its scope". Reading about the typical
> case for this error message in
> <http://caml.inria.fr/pub/ml-archives/caml-list/
2002/10/0cf087feab3ef8dc5ccba5a8592472fb.en.html>
> didn't
> really help me. Why does it make a difference whether ignore is an
> argument?
Because "'a -> unit" does not mean the same thing in both cases. In the
case of Pervasives.ignore, it is a type scheme which denotes all the
types you can obtain by instantiating 'a. On the contrary, when used as
a type annotation to your argument, "'a -> unit" only tells ocaml that
there exists an 'a such that the argument ignore has this type: you can
see that with the following code:
# let foo (ignore: 'a -> unit) = ignore 1;;
val foo : (int -> unit) -> unit = <fun>
where 'a is instantiated by int in the inferred type.
IIRC arguments can not have a generalized type of the form
"forall 'a, 'a -> unit", but methods and record fields support such
types: for instance, you can have:
# module type FOO =
sig
type t
val value : t
end ;;
module type FOO = sig type t val value : t end
# let foo (ignore: <call: 'a.'a -> unit>) =
let module Foo: FOO = struct type t = int let value = 1 end in
ignore#call Foo.value;;
val foo : < call : 'a. 'a -> unit > -> unit = <fun>
========================================================================
10) Camomile 0.6.6
Archive: <http://groups.google.com/group/fa.caml/browse_thread/thread/
26cc06e5aaea298f/1a5483b83ea52ba5#1a5483b83ea52ba5>
------------------------------------------------------------------------
** Yamagata Yoriyuki announced:
I'm pleased to announce Camomile-0.6.6, a comprehensive Unicode
library for OCaml. This is a bug fix release to make its Makefile
compatible to older shells. You can download Camomile 0.6.6 from
here.
<http://sourceforge.net/project/showfiles.php?
group_id=40603&package_id=32800&release_id=429083>
========================================================================
11) Sentence Segmenter
Archive: <http://groups.google.com/group/fa.caml/browse_thread/thread/
fda49194a153e50c/b8778e0e27060a57#b8778e0e27060a57>
------------------------------------------------------------------------
** ramu ramamurthy announced:
This library can be used to segment newspaper style
(english) text articles into sentences. It uses the
Ocaml lexer with a simple set of lexical rules to
classify those periods in the text that end sentences.
This library is released under the BSD license and
is available at:
<http://ramamurthy.ramu.googlepages.com/sentencesegmenter>
The library contains:
* README.txt
* sentsegment.mli (interface)
* sentsegment.mll (implementation)
* segTest.ml (API test)
========================================================================
Using folding to read the cwn in vim 6+
------------------------------------------------------------------------
Here is a quick trick to help you read this CWN if you are viewing it
using
vim (version 6 or greater).
:set foldmethod=expr
:set foldexpr=getline(v:lnum)=~'^=\\{78}$'?'<1':1
zM
If you know of a better way, please let me know.
========================================================================
Old cwn
------------------------------------------------------------------------
If you happen to miss a CWN, you can send me a message
(alan.schmitt at polytechnique.org) and I'll mail it to you, or go take
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archives (<http://alan.petitepomme.net/cwn/cwn.rss>). If you also wish
to receive it every week by mail, you may subscribe online at
<http://lists.idyll.org/listinfo/caml-news-weekly/> .
========================================================================
--
Alan Schmitt <http://alan.petitepomme.net/>
The hacker: someone who figured things out and made something cool
happen.
.O.
..O
OOO
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