Here is the latest Caml Weekly News, for the week of 23 to 30 November, 2004.
Archive: http://caml.inria.fr/archives/200411/msg00200.htmlDamien Doligez announced:
Greetings, We have the pleasure of announcing the release of Objective Caml version 3.08.2 This is a bug-fix release; see below for the list of changes. Upgrading is not urgent unless you have problems with one of the bugs listed below. Only the source is available at the moment. We will provide some binaries in the near future. It is available at http://caml.inria.fr/ocaml/distrib.html -- Damien Doligez for the Caml Team Objective Caml 3.08.2: ---------------------- Bug fixes: - runtime: memory leak when unmarshalling big data structures (PR#3247) - camlp4: incorrect line numbers in errors (PR#3188) - emacs: xemacs-specific code, wrong call to "sit-for" - ocamldoc: "Lexing: empty token" (PR#3173) - unix: problem with close_process_* (PR#3191) - unix: possible coredumps (PR#3252) - stdlib: wrong order in Set.fold (PR#3161) - ocamlcp: array out of bounds in profiled programs (PR#3267) - yacc: problem with polymorphic variant types for grammar entries (PR#3033) Misc: - export <caml/printexc.h> for caml_format_exception (PR#3080) - clean up caml_search_exe_in_path (maybe PR#3079) - camlp4: new function "make_lexer" for new-style locations - unix: added missing #includes (PR#3088)Aleksey Nogin added:
Binary and source RPMs for Red Hat Linux 8.0, 9, Fedora Core Release 1, 2, 3, and Mandrake 10.0 are available at http://rpm.nogin.org/ocaml.html
Archive: http://caml.inria.fr/archives/200411/msg00194.htmlWarren asked:
I'm an undergraduate student studying computer science. My course assignments generally use C, C++, or Java, and I find myself pining for something more elegant. That is, I'd like to teach myself a functional programming language of some kind. I don't think I like all the parentheses in Lisp. But I was very impressed by a Haskell implementation of the usual quicksort algorithm which was very concise -- only 5 lines or so. However OCaml seems to have a larger community and has a reputation for fast executation times, so that seems like a better fit. The academic term at my university is ending soon and I'll have a few weeks of free time on my hands -- I was thinking of checking out a suitable text on some functional programming language from the library and working through some of it. Would doing this be difficult if one were sufficiently motivated? I sort of did something similar with C++ a while ago with some amount of success. Although I've of course Googled around for potential books to select, are there any ones particularly suited for someone in my position? Finally, although OCaml looks interesting, would some other functional language be better for someone new to functional programming? If so, which? I ask because I don't know anyone who uses functional languages or even knows how to use one.Chen Yang answered:
Firstly, I suggest that you should know some basic theory of lambda culculus, which definitely help you understand functional programming better. Then you can write some basic algorithms, such as sorting, binary tree, etc. Here is an good book, http://caml.inria.fr/oreilly-book/ , or you can begin with more simple one, http://www.cs.caltech.edu/courses/cs134/cs134b/book.pdfRichard Jones answered:
I would get yourself a project. You could contribute to one of the existing projects here: http://caml.inria.fr/humps/caml_latest.html or start a new one! I wrote a tutorial for OCaml users which you may find useful: http://merjis.com/developers/ocaml_tutorialJoshua D. Guttman said:
In my opinion, a splendid book that's full of insights into computation and languages and how to solve problems is Abelson and Sussman, Structure and Interpretation of Computer Programs (MIT Press). It uses Scheme, which has the infamous parentheses, but really those aren't as bad as you think. In fact, they're a syntactically minimal way of writing programs, which doesn't get in your way when thinking about problems. An outstanding Scheme implementation is PLT Scheme from Felleisen and his colleagues, now at Northeastern. Having taken a tour through Abelson and Sussman, you're sure to feel at home in OCaml or other functional languages, and probably look at programming in any language with a clearer pair of eyes.Michael Vanier added:
I second this (not just because I teach a course based on Structure and Interpretation of Computer Programs (SICP) ;-)). Also, you should know that the book is available for free on its web site: http://mitpress.mit.edu/sicp . I learned most of what I know of functional programming from reading this book. Another good book is How to Design Programs, which also uses scheme, and which also is available for free on its web site: http://www.htdp.org . This latter book is extremely accessible even to non-programmers, although it's somewhat tedious at first for more experienced programmers. Ocaml is a fantastic second functional language after you've gotten the hang of the functional style, and you can learn it straight from the manuals. And when you want to go further you should learn Haskell and be prepared for serious brain-expansion. The only problem is that once you've learned languages like scheme, ocaml and haskell (and I'll throw in common lisp for good measure), you'll find languages like C, C++, java etc. to be deadly dull and annoying (sort of like a racing car driver being forced to drive a tricycle).Danny Yoo added:
I want to third the recommendation. *grin* There's also a great set of video lectures from the SICP authors: http://swiss.csail.mit.edu/classes/6.001/abelson-sussman-lectures/Martin Berger said:
I have to disagree. while SICP is a brilliant book that i used to teach myself programming from (and nothing i learned as an undergraduate really went beyond), these days, i'd recommend Ocaml to beginners. scheme has one VERY BIG problem: it is untyped (in the sense of static type checking). thinking about types properly is such an important factor in becoming a good programmer. it seems to me that there is little one can learn from scheme that one couldn't learn from ocaml, and probably learn better.Michael Vanier said:
I'm not sure how appropriate ocaml is as a beginner's language. I teach both scheme and ocaml now, and ocaml is very well-liked by advanced programmers (one of whom came up to me raving about his "programming epiphany" after learning ocaml), but I think it would overwhelm beginners. The syntax is pretty involved, for one thing, and there are just a lot of concepts to learn. Cousineau and Mauny's book _The Functional Approach to Programming_ is a good attempt to teach functional programming and ocaml (actually caml-light, but it's basically the same) to a fairly naive audience.William Lovas said:
If you prefer dead trees, a decent book on the functional style is "The Functional Approach to Programming" by Cousineau and Mauny: http://pauillac.inria.fr/cousineau-mauny/main.html As an added bonus, it uses Caml syntax -- but on the minus side, i really do mean "Caml" syntax, and not "O'Caml", so there's a small translation barrier you have to go through. Nothing that's insurmountable with the O'Caml manual handy, though.
Archive: http://caml.inria.fr/archives/200411/msg00204.htmlJean-Baptiste Rouquier announced, and John Goerzen said:
> This lib is used in cameleon and in my own programms. It's available on > http://savannah.nongnu.org/download/cameleon/ and on my own webpage. > It's part of cameleon2 (not yet available) but is also available separately. > > Comments welcome, especially if you know other similar libs. I know Inifiles, > Option from cameleon and I couldn't download ConfigParser from Missinglib. FWIW, you can download it from http://quux.org/devel/missinglib or http://packages.debian.org/missinglib (sources are there too).
Archive: http://caml.inria.fr/archives/200411/msg00213.htmlRichard Jones announced:
I'm pleased to announce the release of perl4caml 0.3.14. This is a fully-featured interface for calling Perl code and libraries from Objective CAML, and includes wrappers around some popular Perl libraries. It is released under LGPL + OCaml linking exception. http://merjis.com/developers/perl4caml New in this release are wrappers around the wonderful WWW::Mechanize, and additional coverage of methods in LWP, HTTP::Request, HTTP::Response, HTTP::Response::Common and HTTP::Cookies. There are also some stability / bug fixes. Note: I'm still looking for someone with a deep understanding of both perlguts and OCaml GC, who can help me get the reference counting - GC interaction working. At the moment perl4caml does not free any Perl structures, so is only recommended for short command-line scripts. There is experimental code in there to handle Perl's reference counting, however it sometimes causes crashes and memory corruption for reasons which are unclear, so it is disabled by default. Rich.  http://search.cpan.org/dist/WWW-Mechanize/lib/WWW/Mechanize.pm#SYNOPSIS  http://search.cpan.org/dist/libwww-perl/  http://www.perldoc.com/perl5.8.0/pod/perlguts.html
Archive: http://caml.inria.fr/archives/200411/msg00248.htmlEvan Martin announced:
I have released version 1.0 of my bindings for libxml's xmlReader API. The minor changes: - Updated Makefile to install libxmlr.a. - Minor documentation futzing. If your existing install works, it is not worth updating. Otherwise, you can get it from here: http://neugierig.org/software/ocaml/xmlr/ There's a short description of the API here: http://neugierig.org/software/ocaml/xmlr/doc/Xmlr.html
Archive: http://caml.inria.fr/archives/200411/msg00257.htmlBenjamin Pierce asked:
I'm sure that, like me, many of you have experienced language-envy when you've seen the very cool libraries for Functional Reactive Programming (Fran, Frob, Yampa, etc.) that have been implemented in the Haskell world. Has anybody tried to do something similar in OCaml? At first sight, it does not seem trivial: the implementations of FRP that I've seen make good use of many of Haskell's special features -- laziness, type classes and qualified types, monads, etc...James Woodyatt answered:
Hello, Dr. Pierce. Yes, I've tried this. Reactive programming is a hobby of mine. I haven't tried building a functional GUI toolkit, since I'm mostly interested in network application services. But you might try checking out the Iom module in my OCaml Network Application Environment project on SourceForge. http://sf.net/projects/ocnae/ Basically, I ported Chapter 30 of Magnus Carlsson's and Thomas Hallgren's joint Ph.D. thesis to OCaml, then generalized it and rewrote it to take advantage of OCaml's mutable data structures inside the scheduler. http://www.cs.chalmers.se/~hallgren/Thesis Be advised: the most current release of Cf_gadget has a serious stack leak in the scheduler, causing some trivial reactors explode on the stack. A fix-- involving yet another complete rewrite of the scheduler-- is already in CVS, and a new release will be coming soon.Gregoire Hamon answered:
You can look at Lucid Synchrone (http://www-spi.lip6.fr/lucid-synchrone/), a functional language dedicated to reactive programming. The syntax is OCaml's and the compiler produces OCaml code (combining both languages is easy). While being stream based, reactivity, which is ensured statically, allows the compiler to produce purely sequential (strict) code. You can write Fran-like code quite easily (I had some examples which I can try to find if you're interested).Benjamin Pierce then asked:
Many thanks to all those who've replied so far to my query about Functional Reactive Programming in OCaml. I got some very interesting pointers, but none closely related to what I was looking for. I should have been more precise in what I asked -- "FRP" in the Haskell community is a term with a much more specific technical meaning than just "reactive programming in a functional style": I was thinking of the line of work initiated by Conal Eliott and Paul Hudak in their Fran library and continued in systems like Frob, Fruit, and recently Yampa. The common idea in these systems is to introduce an abstraction of "signals" -- roughly, functions from time to "values", where the values can be anything from real numbers (conventional signal-processing-type signals) to two- or three-dimensional pictures, to booleans (representing events). What's special is that time is represented as a continuous, real-number quantity. They do all kinds of work behind the scenes to actually compute with behaviors, but what shows through in the API is a very simple, elegant, and powerful set of primitives that can be combined in straightforward ways to achieve very complex effects. See http://www.haskell.org/frp/ for more info. So... is anybody doing THAT in OCaml? Thanks for any (more) pointers.
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