I've found Io very interesting as well, but have never gotten it to build successfully on OpenBSD. It seems like the Io community is fairly Mac-centric, so it's

I've found Io very interesting as well, but have never gotten it to build successfully on OpenBSD. It seems like the Io community is fairly Mac-centric, so it's probably easiest to bootstrap on OS X. Lua also does prototype-based OO* , and is quite a bit more mature (and performs better, etc.). I've been using that instead, and I'm quite happy with it. (It also plays verrrry nicely with C.) * Actually, it's more general than that - Lua has extensible semantics (via metatables). Setting up a prototype-based OO system is dead easy, and is a bit of a cliche example for how metatables can be used.