For the curious: http://github.com/tekktonic/onward , it's a forth and the pushed version isn't really there yet; it's pretty much just an rpn calculator. Locally I'm closer to working but still broken so I haven't pushed.
@clacke I meant it in the literal sense; the pushed version really is just a rpn calculator. Like I said I have a version which implements words on my desktop, but I had to do stuff like homework so it didn't quite catch the "24 hour forth" mark. Not too much work left to be done before then though; I predict <700 sloc total.
@clacke The current commit is now what I have locally, although it shouldn't be on master (think I hit a bug in magit). Basically just need to put together the infrastructure to make the builtins evaluate their arguments. Currently "1 1 - 3 +" will die because - isn't a number, even though the result of its evaluation (0) is a number. Once I have that working I just need to implement the begin and end keywords (when you see end on the top of the stack, create a) 1/2
2/2 new word with the assigned name and pop from the stack into the word's stack until "begin" is hit. Evaluation of a word is just copying all of the contents of the word's stack into the stack in reverse order so that it's as if you were typing the commands in literally. With words and arbitrarily long loops (do math on numbers to feed to rep) I should be turing complete; then just a problem of exposing syscalls and stuff.