Here is the latest Caml Weekly News, for the week of 24 to 31 August, 2004.
Archive: http://caml.inria.fr/archives/200408/msg00367.htmlRichard Jones announced:
[I'll try to keep this brief and to-the-point. Hopefully only very very occasional messages about this to caml-list should be necessary.] A group of business users of Objective CAML, including Nicolas Cannasse and myself, are building a website containing resources for the promotion of the language to business users. The website is here, and we would welcome contributions: http://wiki.cocan.org/ In particular, if you are a programmer or consultant who would like to offer your services to businesses within your area, we would appreciate you adding a note here: http://wiki.cocan.org/people If you are a company which uses Objective CAML, and you don't mind other local businesses contacting you, please add a note here: http://wiki.cocan.org/companies If you are in / run a user group, then add a note here: http://wiki.cocan.org/user_groups If you'd like to know more about our objectives for OCaml in business, then you can read about them here: http://wiki.cocan.org/ocaml_alliance
Archive: http://caml.inria.fr/archives/200408/msg00372.htmlSooHyoung Oh announced:
Changes: - fix some bugs (Thanks Martin) - add "Keyword Hashtable" section - add "Nested Comments" section - add example for lexing ambiguities (chapter 5). - include some examples in complete form - information of the source of document - information of PDF file (A4 size) of the document - information of the source of examples Abstract This is a tutorial on how to use ocamllex which is distributed with Ocaml language. This tutorial borrowed lots of part from flex manual, and some part from Chap. 12 Lexer and parser generators (ocamllex, ocamlyacc). The companion tutorial for ocamlyacc will be available in one or two weeks later. Please mail all comments and suggestions to <shoh at compiler dot kaist dot ac dot kr> This tutorial is work-in-progress. The latest version can be found at http://pllab.kaist.ac.kr/~shoh/ocaml/ocamllex_ocamlyacc/ocamllex-tutorial/index.html . You can find the source of this document in ocamllex_tutorial_src.tar.gz, and for printing, pdf (A4 size) is presented. You can download the source of examples used in this document from ocamllex_example.tar.gz. Last updated: 2004-08-25
Archive: http://caml.inria.fr/archives/200408/msg00374.htmlJohn Goerzen asked:
I come to OCaml from a Python background, and one of the most interesting bits of technology for Python is Jython. Jython is a pure Java implementation of the Python interpreter and native-code libraries. It allows Python programs to run unmodified in a Java environment. More powerfully, though, Python programs can use Java classes as if they were native classes. No glue code is required for this; it Just Works. To a somewhat more limited extent, Python classes can also be made available to Java classes. This makes Python an interesting choice to add more dynamic capabilities to Java code, and it expands the set of available libraries to Python programs to include anything available for Java. I've used these capabilities for several purposes -- one of the more recent is the zxJDBC module, which exposes a Python DB-API interface to any database that has a JDBC implementation. One of my continuing complains about OCaml is the breadth of libraries available for it. It is getting better thanks to the hard work of many, but IMHO, still lags behind Python, Perl, and Java. So one of the things I've been thinking about lately is integrating OCaml with either Java or the .NET CLI in a manner similar to Jython. I've done some googling on the topic and it seems nobody is working on this yet. I just wanted to check and see if that's true. I see several possibilities with both of those paths: * An ocamlc/ocamlrun that execute under Java or .NET and compile/run normal OCaml bytecode * An ocamlopt-equivolent that would compile OCaml code directly to Java or .NET bytecode I have found a language called Nemerle that seems to be very similar to OCaml, though with a different syntax.  http://www.jython.org/  http://nemerle.org/ Thanks!Richard Jones said:
> * An ocamlc/ocamlrun that execute under Java or .NET and compile/run > normal OCaml bytecode This interesting project was posted on the Wiki yesterday. It generates code which runs on the .NET CLR. I'm not exactly sure how, whether it's a modified compiler, or a translator of OCaml bytecode: http://www.pps.jussieu.fr/~montela/ocamil/ What will be interesting will be to see how well it allows one to call .NET libraries, and how well it works on Mono.Lars Nilsson added and John Goerzen said:
> I guess one can always mention F# in this context. > > http://research.microsoft.com/projects/ilx/fsharp.aspx Also, it appears there is a SML version for .NET: http://www.cl.cam.ac.uk/Research/TSG/SMLNET/Raphael Montelatici described OcamIL:
Here are some explanations on OcamIL. OcamIL compiles Ocaml programs to verifiable MSIL bytecode. I have not advertised at all about it so far because I still consider it is not mature yet. Some implementation details: OcamIL is a modified ocamlopt compiler. Modifications are made as late as possible in order to achieve maximum compatibility with ocamlc/opt. One big issue is the compilation of an untyped intermediate language to a typed runtime. Two tracks have been followed : 1) type reconstruction and 2) type propagation 1) The current OcamIL distribution relies on the first approach. It gives enough good results to allow to bootstrap OCamIL and build an Ocaml toplevel for .NET. Interoperability with C# has been successfully tested. 2) However, it leads to unadequate data representations that entail poor performance. I'm currently working on the second approach. This involves a lot of code restructuration. Source files (as a patch to ocaml sources) together with a correct license will appear in the next release (expected late october ?) About interoperability: We do not want to add weird FFI features to the Ocaml syntax. We prefer an IDL approach, inspired by what have been done for Caml and Java by the OJacare project ( http://www.pps.jussieu.fr/~henry/ojacare/index.en.html ). About mono: OcamIL is developped and tested on windows, but I'm willing to make it compatible with Mono. However, mono still lacks .NET compatibility. OcamIL relies on parts of the Reflection library that are not available yet. Moreover, the mono bytecode interpreters behaves strangely: some executables produced by OcamIL don't run in the bytecode interpreter, but do run when previously compiled by the mono bytecode-to-nativecode compiler. Please Mono users wait for the next OcamIL release, which will be announced on this list.Nicolas Cannasse suggested:
> I see several possibilities with both of those paths: > > * An ocamlc/ocamlrun that execute under Java or .NET and compile/run > normal OCaml bytecode > > * An ocamlopt-equivolent that would compile OCaml code directly to Java > or .NET bytecode I started some weeks ago a library to enable the OCaml programmer to manipulate Java bytecode, so it can : - generate valid .class files - read .class files and interpret them in OCaml The library already have a full .class parser but still need the corresponding printer and a small OCaml JVM in order to be able to interpret java bytecode. That might be added easily, people interested in helping or getting informations can contact me directly.
Archive: http://caml.inria.fr/archives/200408/msg00444.htmlShishir Ramam said:
I am interested in starting a SF Bay Area Ocaml SIG to meet on a regular basis. The general idea being to talk all things Ocaml. Would like to poll these forums to see if others are interested (with apologies if you get multiple copies of this email). Please get in touch offline if this is of interest to you.He later added:
Since there is some interest, I have started a yahoo group to manage the forum - http://groups.yahoo.com/group/ocaml-sig-bayarea/join The link has also been updated at the Ocaml Alliance Network Wiki. My email was already on there. Apparently, Ocaml is not alone in being quick! :) Please feel free to sign up. Postings are restricted to members only, in an attempt to limit spam. Let's see how that works out. From now on, all related communications will be on the group mailing list. Thanks for tolerating the noise if this was not of interest to you.
Archive: http://caml.inria.fr/archives/200408/msg00472.htmlIn the middle of a thread about C++ throws, Xavier Leroy said:
> I do find it amazing that C++ would be dumb enough to try to scaffold raw > stack frames, instead of using some kind of dynamic link pointers to reach > each frame. There are indeed two "schools" of exception handling: one that unwind stack frames one by one until an exception handler is found, and one that maintains at run-time a chaining between exception handling blocks on the stack, so that no stack searching is necessary when an exception is thrown. The first school is exemplified by C++, Modula-3, Java and C#; the second school by Lisp, Caml and to some extent Prolog (if you view backtracking as a generalization of exception handling). A good description of the two approaches is the following paper: "A Single Intermediate Language That Supports Multiple Implementations of Exceptions",, Norman Ramsey and Simon Peyton Jones, PLDI 2000. http://research.microsoft.com/Users/simonpj/Papers/c--/c--exn.htm The two approaches have very different performance trade-offs. To make things worse, many people from the first school are not even aware of the second approach. So, as usual, there is no hope to see the world converge on a single exception mechanism. > How in the world would any kind of cross-language > interoperability ever function if this were the case. Cross--language exception interoperability is certainly a challenge. There are C compilers (MSVC, Tru64 cc) that provide C++-style exception handling compatible with C++, but that's not too hard given that the same compilers double as C++ compilers :-) Some ABI (Application Binary Interfaces) specify the format of stack descriptors and the unwinding algorithm, but not all. The only portable way is to install catch-all exception handlers at the boundaries between the two languages whose job is to convert exceptions from one language into exceptions from the other language. The Caml bytecode interpreter does something like this when interoperating with C, using setjmp/longjmp to represent exceptions on the C side. For C++ to Caml callbacks, you can use callback_exn to invoke the Caml code; it reifies whatever Caml exceptions can get out of the Caml code as special return values, which the C++ wrapper can test and then throw the appropriate C++ exception. For the reverse direction (Caml calling C++), I'm afraid the only solution is to use a C++ catch-all clause to turn C++ exceptions into Caml exceptions. Hope this clarifies the issue.
Archive: http://caml.inria.fr/archives/200408/msg00426.htmlCristiano Calcagno said:
The National Science Foundation (NSF) has kindly provided a number of stipends to support students travel and participation to attend the MetaOCaml Tutorial and/or the MetaOCaml Workshop: http://metaocaml.org/tutorial4/ http://metaocaml.org/workshop04/ Awards will be made on the basis of relevance to the students education and research activities. To apply, please send an email to email@example.com by September 5th. The email should include: 1) Primary interest (Tutorial or Workshop) 2) Explanation of relevance to your current educational and/or research goals (200-500 words) 3) Secondary interest 4) Explanation of relevance 5) Estimated travel expense Reimbursements will be made based on submitted expense receipts. Students submitting papers to the MetaOCaml Workshop are eligible for stipends. Amount of stipend will be indicated when you are notified of the result of your application. Applications should be sent to firstname.lastname@example.org by September 5th, 2004.
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