Ruby and python have been mentioned many times on LtU, but I would like the opinnion of gurus here. Which language is more interesting for those who have deeper knowledge of programming language theory?

I'm not so concerned with speed of respective VMs, the community around these languages, even their syntax, etc. I'm iterested in the languages (and their APIs I suppose).

For example, for practical programming, are ruby's continuations significantly better than python's co-routines (2.5)? How do 'lambda' functions in each language compare?

Is one language closer to 'functional' programming than another? Is one language better than another for building logic programming or constraint logic programming constructs? Is one language better than another for building the kind of functionality found in concurrent languages (erlang, Oz)?