Thanks for these hints… I haven’t seen (.%()<-) which seems to be an extension of the core language.
Here Error: Library "netcgi2" not found - #9 by geoffder is an other series of issue… and I guess that having a well integrated interface with Apache is not something exotic if I want something done which could be done easily in Perl, Python, PHP, Java (tomcat)…
Perhaps I should go to a pure Ocaml way (Dream ?) and have Apache relaying from HTTPS:443 to Dream:8080… (I am not sure Dream could interface with letscrypt)
The answer « Condition moved from systhreads into the stdlib recently, so I suspect there is a versioning issue. » seems to indicate that we can have something working today, and not tomorrow ! Perhaps we should have something in a Debian way. A testing release could break some times, but before a switch to a stable release a freeze period prevents something nasty then the stable release is born, evolves with bug correction and not something which could break too many things.
Debian/stable could be boring, there are not many things very new, but it works.