Re: [Caml-list] Build number and date in OCaml?

[Alain Frisch <alain.frisch@lexifi.com>]

On 04/09/2013 01:38 PM, Étienne André wrote:
> I quite stupidly used the Unix.gettimeofday() function before realizing
> that it is of course executed at runtime.

As others suggested, you can tell your build system to generate an ad 
hoc file containing the compile-time information.  Another approach is 
to use a preprocessor to inject such compile-time information into the 
source code "on the fly" during its compilation.  This can be done with 
a dedicated Camlp4 syntax extension or a -ppx preprocessor (available in 
trunk only, with syntactic extension points being designed in the 
extension_points branch of the OCaml SVN).

As an illustration of the -ppx approach, I've created a tiny 
preprocessor which uses the OCaml toplevel to evaluate expressions and 
inserts the result as constants in the compiled code.

The source code for this -ppx preprocessor can be found here:

http://caml.inria.fr/cgi-bin/viewvc.cgi/ocaml/branches/extension_points/experimental/frisch/eval.ml?&view=markup

and here is an example of what you can write with it:

http://caml.inria.fr/cgi-bin/viewvc.cgi/ocaml/branches/extension_points/experimental/frisch/test_eval.ml?&view=markup

(To play with it, you need to checkout the extension_points branch and 
after compiling it: cd experimental/frisch && make eval)

-- Alain