On: Why Functional Programming Matters (1984) [pdf]

[lispm]

By using all the imperative, procedural and object-oriented features of Lisp.

In many ways the early MIT Lisp Machine morphed into a Flavors Machine in the early 80s.

Remember, Lisp is a multi-paradigm language.

[pjmlp → lispm]

But that is the thing, none of the successful FP languages in the industry are pure FP, rather multi-paradigm, even if functional first.