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

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