I remember first running into this point with <a href="http://xahlee.org/UnixResource_dir/writ/notations.html" rel="nofollow">http://xahlee.org/UnixResource_dir/writ/notations.html</a> and I'm sure Slava or somebody has pointed out that in postfix languages like Factor and Forth everything is essentially chained which very naturally leads to a function composition style. And that despite the "reverse" nature of RPN it often ends up being "forward", witness in Factor REPL actually being REPL instead of L(P(E(R))).