oops, I realized now that my answer did not go to the list. For the record here is it: Thanks to everybody for the answers and to Henning Thielemann for the useful links:

http://haskell.org/haskellwiki/Qualified_names

http://haskell.org/haskellwiki/Category:Style

I agree with apfelmus that recursive module should be supported (as the standard requires) this would make it easier to use one module per main type (the distributed approach), this approach was also what I had in mind, but it comes very close to introducing by hand one namespace per type from which came my rant about missing namespaces... Fawzi