[crntaylor]

This is really interesting - I didn't know about that snippet of Lisp history. So the expression we'd write today as

  (car
    (append
      '(a b c)
      '(d e f)))

Would originally have been written in M-expression form as

  car[append[(a b c); (d e f)]]

Programming in Lisp might be a very different experience if M-expressions had caught on!

[Anon84]

It would be called programming in Mathematica ;)