Here is the latest Caml Weekly News, for the week of 29 June to 06 July, 2004.
I am pleased to announce a new release of ocaml-fileutils. This library implements some new function : - cmp : compare file - du : give the disk usage of some files - stat : abstraction of Unix.stat - readlink : return a path with link solved to real location This new version comes in particular with a rewritten "find" command which take an "exec" and "accu" parameter allowing to customize the operation done during the directory traversal. ( You can have the same behavior of the previous find command by this way : find test current_dir (fun lst fln -> fln :: lst)  ). This new command embed a recursion prevention system, allowing not to traverse the same directory twice ( ie, it handles symlink like : ln -s . recurse ). Most of the command also provide a ~follow parameter which dictate the way ocaml-fileutils should follow symlink ( by default Skip, but can also be Follow, AskFollow, SkipInform... ) General : Ocaml fileutils is aimed to be a platform independent library to perform operation on file like : - mv - cp - rm - mkdir - touch - which... Comes also with a module to manipulate abstract filename : - classification - make_relative : made a filename relative to another - make_absolute :... Link : http://www.carva.org/sylvain.le-gall/ocaml-fileutils.html
> in the original lex it is possible to use startconditions. > Is that possible in ocamllex too? You can simulate startconditions with several entry points and a global variable. See my message http://caml.inria.fr/archives/200309/msg00027.html (just ask again if that is not clear enough).
To all OCaml users who track the CVS or are willing to beta-test: We are progressing towards a release of OCaml 3.08, and at the same time experimenting with a two-branch development model, one branch for short-term bug fixes and the other for longer-term developments. If this model turns out to work well, we hope it will make it easier for users to benefit from bug fixes between major releases, and speed up the release process. Users who track the CVS sources from camlcvs.inria.fr are encouraged to switch to the current release branch, which is labeled "release308". This is the branch where we currently do bug fixes before release 3.08 and where we'll do post-release bug fixes if needed. It is currently more up-to date than the main branch, which is the development branch, and will remain so for a couple of months at least. To switch your CVS checked-out sources to the release branch, just do cvs update -r release308 Users who are willing to beta-test the upcoming 3.08 release should also get the sources from the "release308" branch of the CVS: cvs -d ":pserver:email@example.com:/caml" checkout -r release308 ocaml Now is a very good time to test and report bugs. Thanks for your cooperation.Skaller asked and Xavier Leroy answered:
> OK, any hints on what things to look for? > Expected problem areas, performance changes, > cute new features, etc? The change log (file "ocaml/Changes" in the CVS sources) is relatively up-to-date. Perhaps the biggest (internal) change is in the representation of objects and compilation of classes, so if you have object-heavy programs, that would be a good test.
> I was looking for documentation about the OCaml implementation, or > some discussion about the internals, especially the compiler and > runtime. I searched the list archives and got no results (maybe I > didn't do it right). So, there appears to be none. There was a project on Sourceforge about this: http://www.sourceforge.net/projects/docaml It's mostly dead but there's a couple of LaTeX files lying in the CVS. Could be a starting point.Alan Schmitt added:
(Editor's note: I am Alan Schmitt, so this is a shameless plug.) It's indeed dead, but if there is someone willing to revive it, I would definitely participate again.
The latest 3.08 CVS solves the problem (for GlSurf at least). When I have the too Glsurf thread (on computing, one for drawing GL (I keep pressing a key to rotate the surface) and I launched povray from Glsurf for a rendering, then I get one third of cpu each which is perfect) Just a last question: Now I saw that for "non broken" sched_yield, the call is still present. Are you sure that releasing the mutex is not enough to tell the scheduler it may be a good time to give some cpu to another caml thread blocked on the same mutex ? But I am sure you tested that too and this is why the call is still there when possible ;-)Xavier Leroy answered:
> Just a last question: > Now I saw that for "non broken" sched_yield, the call is still present. > Are you sure that releasing the mutex is not enough to tell the > scheduler it may be a good time to give some cpu to another caml thread > blocked on the same mutex ? In general, when there's code in the Caml implementation, it's for a good reason. > But I am sure you tested that too and this is why the call is still > there when possible ;-) Yes, I tested. Spent more than one day setting up and refining a test harness, then running it on a variety of Linux and non-Linux systems. Had to install a Fedora Core 2 somewhere to assess the damage done in kernel 2.6. In the meantime, read a bunch of condescending mailing list posts along the lines of "if you're using sched_yield(), you must be doing busy-waiting and that's wrong". (Guess what? I'm not doing busy waiting!) The conclusions are clear: sched_yield() does improve fairness and has no significant costs in the situation corresponding to Caml threads (contention on a master lock); and the Linux 2.6 developers managed to make sched_yield() useless for this purpose. If the above sounds mildly irritated, that's because I am.
> Is there any way to define infix operators in > OCaml? Yes. This is described in the excellent book "Developing applications with objective Caml" in the "Functional core of Objective CAML" chapter, on page 25 under the heading "Declaration of infix functions". This book is freely available in electronic form here: http://caml.inria.fr/oreilly-book/html/index.html Basically, use only symbols in infix function names and define the function using the syntax: # let ( ++ ) c1 c2 = (fst c1)+(fst c2), (snd c1)+(snd c2);; val ( ++ ) : int * int -> int * int -> int * int = <fun> # (2, 3) ++ (3, 4);; - : int * int = (5, 7)Richard Jones then asked and Benjamin Geer answered:
>Is this book really published by O'Reilly? The French version is published by O'Reilly France, but the English translation hasn't been published. I recently asked the head office why they haven't published anything in English about functional languages, and they said it was because books on functional languages didn't sell very well.
I'm pleased to announce the long-awaited CDuce 0.2.0 release. CDuce is a strongly typed functional language, with first-class and overloaded functions, adapted to the manipulation of XML documents. CDuce is fast, type-safe, and conforms to basic XML standards. More information about CDuce: http://www.cduce.org/ Source distribution: http://www.cduce.org/download.html A GODI package is available (under the name apps-cduce). This is the recommended way to build CDuce from sources. Packages and ports for other systems (Redhat, Debian, Mac OS X, FreeBSD, WinXP) will come later. W.r.t. CDuce 0.1.1, the release adds separate compilation, a preliminary implementation of an XML query language, and several other improvements. The release also includes a new type-safe OCaml-CDuce interface, which is described at: http://www.cduce.org/manual_interfacewithocaml.html This interface allows: 1- to use existing OCaml libraries within CDuce, and 2- to project an OCaml signature (.cmi) to a CDuce unit in order to use it in a mixed OCaml-CDuce project. It makes CDuce of special interest to OCaml users. Interested people are invited to join the CDuce users mailing list: http://www.cduce.org/mailing.html Enjoy, and let us know about your experience ! Alain Frisch, on behalf of the CDuce team (http://www.cduce.org/team.html)
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