It's maybe a not very well known fact but McCarthy's original LISP proposal used M-expressions instead of S-expressions; M-expressions were then transformed int

It's maybe a not very well known fact but McCarthy's original LISP proposal used M-expressions instead of S-expressions; M-expressions were then transformed into S-expressions. Using S-expressions directly, however, turned out to be more popular amongst programmers. With M-expressions, this would look like: he[will[be[dearly[missed]]]]