I didn't talk about how to implement (or represent) the body of the function! And besides, Church seemed to like single arguments, so actually he would write so

I didn't talk about how to implement (or represent) the body of the function! And besides, Church seemed to like single arguments, so actually he would write something like that. :) Physicists wouldn't (my degree is in physics). Programmers would write f(x,y,z){return {x,y,-z};}. But actually, I would say that this is nasty because of asymmetry - it can't consume it's own output. f(p){return {p.x,p.y,-p.z}} where p = {x,y,z}