I'm thinking about building a new MUD server (for those who are less
ancient than I, think "MUD == text only MMORPG"). I'd like to allow
players to build and program objects in the world, but I'd rather avoid
having to write my own programming language. I was wondering whether an
existing scripting language like Ruby might be useable?

The first problem is, of course, that I don't want the players to be
able to do _everything_ the language offers. Their code should only
affect the running of the world, and they should not be able to change
or delete files on my system or do other nasty things.

I'm aware of the $SAFE setting and the tainting procedure, but I'm not
sure how I could use this to do what I want. Any suggestions?

Malcolm