Hello,

very often I  have great difficulties to understand why I got a 
compilation error in OCaml.
Instead of polluting this list with low level questions I give the 
erroneous code and the questions
I have on the wiki page
http://galileo.lct.jussieu.fr/~frames/WIKI/mediawiki/index.php/OCaml_Difficulty_serialize_list

I shall be very grateful if some of you would be interested to go there 
and solve my problem.

François Colonna