When I look at some of the fundamental differences between lisp and the mainstream languages (like everything-as-expressions and explicit scoping of variables and functions), I realize that Lisp is centuries ahead of its time. How long is it going to take mainstream languages to implement explicit scoping like let and flet? 75 years after lisp was born? How long for everything-as-expressions (which gives code a logical structure and eliminates the need for throwaway variables)? 100 years? 200 years? Will we even have programming languages by then?