Ok, thank you for the answer.
Can someone tell why things went wrong ?
I'm reading the discussion on Tcl core mailing list.
Some people seems to be in the hurry to deliver tcl 9.0
Tcl 9.0 is the opportunity to break backward compatibility.
Break compatibility, ok, but for big, not small improvement
If the change is just about "abstract list" or "encoding", it is not enough...
Why not include in Tcl 9.0, all the changes that will make tcl quadcode possible ?
The goal to Jit-Compile tcl isn't good enough for Tcl 9.0 ?
Shall we wait for Tcl 10.0 ?