Almost no one likes Tcl, but I think it used(uses) a nice model for concurrency. Much better than Python's. Interpreter as a library, all state encapsulated in

Almost no one likes Tcl, but I think it used(uses) a nice model for concurrency. Much better than Python's. Interpreter as a library, all state encapsulated in a reentrant interpreter object, different interpreters running in different threads that can send messages to each other, no need for expensive serialization deserialization (like in Python) because the interpreters are in the same process, ... so much nicer.