What language features distinguish Mathematica from lisp? Are we just talking about the m-expression syntax, or are there more fundamental differences?
I don't know enough about lisp implementations to know if these differences still hold, but they still hold for Clojure and ClojureScript, for example. Though some people have done some experimentation like https://github.com/kovasb/combinator
In the email under discussion though Wolfram was beginning work on SMP, which preceded Mathematica by about 6 years and influenced the design of Mathematica both in what to do and what not to do: http://blog.stephenwolfram.com/2013/06/there-was-a-time-befo...