Re: [stack] Barebone implementation of concatenative language in c or c++

I'm really grateful for suggested implementations, and I'm sure that those are useful even in production environment. However I'm looking for a toy implementation so I could quickly understand what happens under the hood of stack languages. Something designed for pedagogical purposes not for speed or efficiency. Something small enough that could be written over the weekend from scratch and contains just the bare minimum of the stack operations so it could be called interpreter.
 Or if you can't think of something like that what are the bare minimum of operators so I could call a language concatenative:
For example from reading Brent Kerby Theory of concatenative combinators http://tunes.org/~iepos/joy.html if I implement : swap, dup, zap, unit, cat, cons, i, dip + (numbers and symbols) would that be enough to have a primitive joy like language?