I think the question is what does portable mean, or is there a better word to use than portable. It clearly doesn't just mean written in C or C++. From the link

I think the question is what does portable mean, or is there a better word to use than portable. It clearly doesn't just mean written in C or C++. From the linked page -- "It currently runs under CLisp and SBCL, Clojure, Scheme, Ruby, Python, the JVM and Javascript."