I agree that Tcl isn't mainstream and thus a lot of concepts used by Tcl are not mainstream, but other than that it's got a lot going for it. Tcl's string repr

I agree that Tcl isn't mainstream and thus a lot of concepts used by Tcl are not mainstream, but other than that it's got a lot going for it. Tcl's string representation for objects is just a serialization/deserialization mechanism, which seems to be pretty popular in other languages as well. Additionally all of the cool things in Tcl such as coroutines, threads (as an additional, but included, package), great documentation delivered as man pages, virtual filesystem access, virtual time, safe interpreters for running untrusted code, a stable ABI (stubs) so that compiled extensions can be used for decades, a small memory as well as disk footprint, extremely cross-platform, easy to embed into larger programs as an extension language, easy to compile a large static program with Tcl as the "main" entrypoint, native BigNum support, many thousands of great packages, .... What would a modern take on Tcl improve on Tcl that Tcl couldn't just build easier ?