Previous week Up Next week


Here is the latest Caml Weekly News, for the week of December 12 to 19, 2006.

  1. Announcing OMake 0.9.8
  2. A few patches to Ocaml 3.09.2
  3. compiling ocaml into a shared object
  4. ocamlnet-2.2rc1 release candidate
  5. An OCaml program was in 2nd position at latest International Free Software Contest

Announcing OMake 0.9.8


Aleksey Nogin announced:
We are proud to announce the latest release of the OMake Build System - 
OMake version 0.9.8. 
OMake is a build system designed for scalability and portability. It 
uses a syntax similar to make utilities you may have used, but it 
features many additional enhancements, including the following. 

  - Support for projects spanning several directories or directory 

  - Fast, reliable, automated, scriptable dependency analysis using MD5 
    digests, with full support for incremental builds. 

  - Fully scriptable, includes a library that providing support for 
    standard tasks in C, C++, OCaml, and LaTeX projects, or a mixture 

    Often, a configuration file is as simple as a single line 

    .DEFAULT: $(OCamlProgram prog, foo bar baz) 

    which states that the program "prog" is built from the files,, and This one line will also invoke the default 
    standard library scripts for discovering implicit dependencies in 
    OCaml files. 

  - Full native support for rules that build several files at once. 

  - Portability: omake provides a uniform interface on Linux/Unix 
    (including 64-bit architectures), Win32, Cygwin, Mac OS X, and other 
    platforms that are supported by OCaml. 

  - Built-in functions that provide the most common features of programs 
    like grep, sed, find, and awk. These are especially useful on Win32. 

  - Active filesystem monitoring, where the build automatically restarts 
    whenever you modify a source file. This can be very useful during 
    the edit/compile cycle. 

  - A built-in command-interpreter osh that can be used interactively. 

OMake preserves the style of syntax and rule definitions used in 
Makefiles, making it easy to port your project to OMake. There is no 
need to code in Perl (cons), or Python (scons). However, there are a few 
things to keep in mind: 

 1. Indentation is significant, but tabs are not required. 
 2. The OMake language is functional: functions are first-class and 
    there are no side-effects apart from I/O. 
 3. Scoping is dynamic. 

OMake is licensed under a mixture of the GNU GPL license (OMake engine 
itself) and the MIT-like license (default configuration files). 

OMake version 0.9.8 in major feature enhancements and bugfixes release. 
The changes in this version include: 

   - The conversion from OMake expressions to shell command lines went 
     through a major redesign to make it more consistent and less 
   - OMake documentation was significantly reorganized. 
   - OCaml build rules: Added experimental improved dependency scanner 
     using the upcoming "ocamldep -modules" feature; added support for 
     the Menhir parser-generator. 
   - Added a number of new options to control OMake's output and 
     verbosity; OMake is now more silent by default. 
   - Many more improvements and bug fixes. 

For a more verbose change log, please visit . 

Source and binary packages of OMake 0.9.8 may be downloaded from . In addition, OMake 
may be obtained via the GODI packaging system. 

To try it out, run the command "omake --install" in a project directory, 
and modify the generated OMakefile. 

OMake 0.9.8 is still an alpha release.  While we have made an effort 
to ensure that it is bug-free, it is possible some functions may not 
behave as you would expect.  Please report any comments and/or bugs to 
the mailing list and/or at

A few patches to Ocaml 3.09.2


Piotr Wieczorek announced:
As part of my master's thesis I've written a few patches to the Ocaml 
3.09.2 compiler. 
You can find them under: 
export.patch - lets you specify signatures of submodules of packed 
module to be included in signature of the packed module. 
    It adds command line argument -export "<module_name1> <module_name2>..." 
extsig.patch - makes compiler to search for signature of the given name 
in .cmi files. 
    You can write: "import Sig" in mli file and it makes compiler to 
look for sig.cmi file and load signature from the file. 
sigops.patch - lets you create new signature based on source signature 
by specifying which fields of the signature should/should not be exported. 
    You can write "include Sig without (val foo and type bar)" or 
"include Sig using (val rhu and type barb)" 
retyping.patch - lets you retype bytecode module to use new signature 
being subtype of the signature of the module 
    It adds command line argument "ocamlc Mod.cmo -retype -o 
new/Mod.cmo" - if there is Mod.cmi in "new" directory it will try to 
make it signature of the new/Mod.cmo module. 
whole.patch - patch being sum of all the above mentioned patches.

compiling ocaml into a shared object


Hendrik Tews asked:
could somebody tell me how to compile ocaml sources into a shared 
object that can be loaded with dlopen? The following message 
seems to tell me that this is possible:

I tried 

  ocamlopt -output-obj -o 

but on 

  dlopen ("/home/tews/src/ocaml/", RTLD_LAZY); 

I get 

  dlopen error: /home/tews/src/ocaml/ only ET_DYN and ET_EXEC can be loaded 

Passing -ccopt -shared to ocamlopt changed nothing. In fact it 
seems that -output-obj discards all -ccopt options!
Richard Jones answered:
It's tricky, but I managed to compile the bytecode interpreter and 
bytecode into a shared object.  See the source for 
(actually there's a 
much newer version in CVS, but I don't think the 
linking issue changed at 
For AMD64, see also:
Oleg also answered:
It is possible: MetaOCaml in the native mode does exactly that. To be 
more precise, evaluating `.! .<code here>.', that is, `running' the 
code expression, is equivalent to invoking ocamlopt (as a library) to 
compile `code here', making a shared object, and loading it into the 
running program. 
For more details (the code, a few tests and the Makefile), you might 
want to look into the directory `natdyn' of the MetaOCaml 

Yet it is awfully tricky -- perhaps trickier than one may realize. The 
problems may occur long after everything is deemed working. For one 
thing, Ocaml native runtime makes an assumption that the data segment 
of a program is contiguous. With the dynamically linked code this 
assumption is no longer true, and subtle bugs emerge (see below). 

After you have loaded a shared object, chances are you'd like to 
invoke an OCaml function from there. That is also tricky: the stack 
frame has to be set up appropriately. If not -- everything works, 
until the major garbage collection. At which point, you get the 
segmentation fault. 

Here's an example of a subtle bug (which also may be present in the 
`Ancient' extension announced on this list some time ago). 

        let v = Array.create 256 iv in 
        Array.length v 

where iv is a _float_ datum that is a literal in a loaded 
shared object, or had been evicted into the Ancient heap. Now, what is 
the reported length of the allocated float array of 256 elements? 128. 
Exactly half of what is allocated. Weird, eh? 

This problem has actually happened, please see the MetaOCaml list for 
discussion. It took a couple of days just to understand the problem. 

The natdyn part of MetaOCaml does work, I believe correctly. However, 
the implementation takes advantage of the fact that some code just 
cannot be part of MetaOCaml quotations. In particular, MetaOcaml 
quotations cannot contain any declarations (of data types, of 
exceptions) and any module expressions (in particular, modules 
requiring initialization). These limitations of natdyn can be remedied 
(OTH, since natdyn was needed quite urgently, one may be justified in 
taking advantage of the domain knowledge to simplify the problem).

ocamlnet-2.2rc1 release candidate


Gerd Stolpmann announced:
there is now a release candidate of the upcoming ocamlnet-2.2 library 
"The Best of 2006": 

Developers interested in the upcoming 2.2 version can have look at it, 
and experienced developers are invited to test it, and to help finding 
the remaining bugs and problems. This version will be the final release 
if no serious bugs are found. The release will happen 
before December 31. 

In the rest of this (long) email, I'll explain certain aspects of this 

1. What's new in ocamlnet-2.2 
2. Release notes 
3. How you can help testing 
4. Resources 
5. Credits 


1. What's new in ocamlnet-2.2 

Ocamlnet now includes equeue, netclient, and rpc 

These libraries were previously distributed as separate software 
packages. All four libraries form now together the new ocamlnet-2.2. 
This allows much deeper integration of their functionality. 

Building servers with Netplex 

The framework Netplex simplifies the development of server applications 
that require the parallel execution of requests. It focuses on 
multi-processing servers but also allows multi-threading servers. 
Netplex manages the start and stop of processes/threads, and dynamically 
adapts itself to the current workload. Netplex allows it to integrate 
several network protocols into one application, and as it also supports 
SunRPC as protocol, one can consider it even as component architecture. 
Furthermore, it has infrastructure to read configuration files and to 
log messages. 

Ocamlnet includes add-ons for Netplex to build SunRPC servers, web 
servers, and web application servers (the latter over the protocols AJP, 
FastCGI, or SCGI). 

The revised API for web applications 

The library netcgi2 is a revised version of the old cgi API (now also 
called netcgi1). The changes focus on restructuring the library in order 
to improve its modularity. It is hoped that beginners find more quickly 
the relevant functions and methods. The API is essentially the same, but 
the support for cookies has been enhanced. The connectors allowing a web 
server to talk with the application have been completely redeveloped - 
all four connectors (CGI, AJP, FastCGI, SCGI) support the same features. 
The connector for SCGI is new. The connector for AJP has been upgraded 
to protocol version 1.3. There are Netplex add-ons for the connectors. 

The old API is still available, but its features are frozen. It is 
recommended to port applications to netcgi2. 

Improvements for SunRPC applications 

It is now possible to use the SunRPC over SSL tunnels. All features are 
available, including asynchronous messages. As a side effect of this, 
the SunRPC implementation is now transport-independent, i.e. it is 
sufficient to implement a few class types to run RPC over any kind of 

Furthermore, a few details have been improved. SunRPC servers can now 
implement several RPC programs or program versions at the same time. 
SunRPC clients can now connect to their servers in the background. A few 
bugs have been fixed, too. 

Shared memory 

As multi-processing has become quite important due to Netplex, Ocamlnet 
supports now the inter-process communication over shared memory. The 
implementation is brand-new and probably not very fast, but shared 
memory makes sometimes things a lot easier for multi-processing 

Old things remain good 

Of course, this version of Ocamlnet supports the long list of features 
it inherited from its predecessors. This includes an enhanced HTTP 
client, a Telnet client, a (still incomplete) FTP client, a POP client, 
and an SMTP client. The shell library is an enhanced version of 
Sys.command. The netstring library is a large collection of string 
routines useful in the Internet context (supports URLs, HTML, mail 
messages, date strings, character set conversions, Base 64, and a few 
other things). 

2. Release notes 


In general, the stability of this version is excellent. About 90 
% of the code has been taken over from previous versions of ocamlnet, 
equeue, netclient, and rpc, and this means that this code is already 
mature. About 10 % of the code has been newly developed: 

- netcgi2 is a revised version of the cgi library. Large parts 
  are completely new. 

- netplex is the new server framework. Fortunately, it could already 
  be used in a production environment, and it has proven excellent 
  stability there. 

- netcgi2-plex combines netcgi2 and netplex. 

- nethttpd has now the option to use netcgi2 as cgi provider 
  (configure option -prefer-netcgi2). 

- netshm adds shared memory support. 

- equeue-ssl and rpc-ssl add SSL support to the RPC libraries. 

Known Problems 

There are known problems in this release which won't be solved 
until the release of 2.2 but in a later version: 

- There is no good concept to manage signals. This is currently done 
  ad-hoc. For now, this does not make any problems, or better, there 
  is always the workaround that the user sets the signal handlers 
  manually if any problems occur. 

- The new cookie implementation of netcgi2 should replace the old 
  one in netstring. Users should be prepared that Netcgi.Cookie 
  will eventually become Nethttp.Cookie in one of the next releases. 

- In netcgi2-plex, the "mount_dir" and "mount_at" options are not yet 

- In netclient, aggressive caching of HTTP connections is still 
  buggy. Do not use this option (by default, it is not enabled). 

- The FTP client is still incomplete. 

3. How you can help testing 

It would be great if experienced developers tested the libraries, 
especially the new and revised ones. Discussions should take place in 
the Ocamlnet mailing list (see resources section below). 

It is important to know that this version of Ocamlnet also includes the 
libraries formerly distributed as equeue, netclient, and rpc. If you 
upgrade an O'Caml installation, you _must_ remove old versions of these 
libraries prio to the installation of the new Ocamlnet. 

For GODI users, there is a convenient way of installing ocamlnet2. First 
install GODI as usual (either for O'Caml 3.08 or 3.09). Then, change 
godi.conf, and add the line 


update packages and rebuild. You can install 


where the latter four packages contain add-ons that need further 
libraries to be installed. The packages 

godi-equeue*, godi-rpc, godi-netclient 

are only fake packages that include godi-ocamlnet as predecessors. 

4. Resources 

On online version of the reference manual can be found here: 

The current development version is available in Subversion: 

Note that the ocamlnet file tree in Sourceforge refers to 
ocamlnet-1 only. 

There is a mailing list for Ocamlnet development: 

In case of problems, you can also contact me directly: 
Gerd Stolpmann <> 

5. Credits 

A number of people and institutions helped creating this new version: 

- Christophe Troestler wrote the revised CGI library 

- The California State University sponsored the development 
  of Netplex and the SSL support for SunRPC. Special thanks 
  to Eric Stokes who convinced the University, and David 
  Aragon for his business support. 

- All companies who hired me this year and made it possible 
  that I can make a living from O'Caml development. Without 
  that it would have been impossible to put so much energy 
  into this. Special thanks go to Yaron Minsky and Mika 

An OCaml program was in 2nd position at latest International Free Software Contest

David Mentré announced:
For information, an OCaml program, demexp, won the 2nd prize of latest
International Free Software Contest (Trophées du Libres) in Soissons,
France, latest November (category Public Services, /Application pour
structures publiques et collectivités/).

Apparently, the jury was kind enough to accept the esoteric language we
used. :-)

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}$'?'&lt;1':1

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 and I'll mail it to you, or go take a look at the archive or the RSS feed of the archives.

If you also wish to receive it every week by mail, you may subscribe online.

Alan Schmitt