Erlang does it, but it requires an extensive system, and the application programmer must support it, too: [0], [1]. [0] https://www.erlang.org/doc/design_princ

Erlang does it, but it requires an extensive system, and the application programmer must support it, too: [0], [1]. [0] https://www.erlang.org/doc/design_principles/release_handling.html https://www.erlang.org/doc/design_principles/release_handlin... [1] https://www.erlang.org/doc/man/gen_server.html#Module:code_change-3 https://www.erlang.org/doc/man/gen_server.html#Module:code_c... It's... cumbersome, let's put it this way, and mind you, Erlang makes it happen at "safe" points, when the code being replaced is idle.