- safety: the standard Tcl interpreter is runtime-safe, and Safe-Tcl
is all about system safety.
- GUI: Motif GUI provided by Tk, with Windows and Mac in development.
I don't believe they're going with a portable GUI interface: a module
negociates the user interface API at runtime.
- concurrency: no.
- FFI: very clean and simple, but only for "trusted" code.
- Module system: Tcl is traditionally weak on this, but I hear
they're actively working loading untrusted modules. I'm not sure what the strategy is for namespace management.
- Exceptions: catch/throw, as opposed to try/except.
- Types: Tcl has not objects with inheritance, though there
are a number of "aftermarket" options for this. However, the
standard library interfaces don't use inheritance. I hear
work on this is in development.
- The tcl-dp extension provides an interface to sockets,
but I don't know if they've come up with or enforced any
security policies; i.e. I don't know if the untrusted code
can get at the tcl-dp API.
Tcl is distributed under an MIT/X/Berkeley style copyright.
As long as that continues, I see no IPR issues.