The lambda calculus is sort of at the intersection of math and computer science, and it's actually very simple. The mess above is a bit of a parlor trick. It is a composition of lots of very simple parts to make a complex whole. What is interesting about it (IMO) is that the whole actually turns out to be a lot less complex than you might at first suspect, and once you've put it together, it actually works the way theory says it does.

If you want to learn about it just Google for 'lambda calculus'. You'll find a zillion tutorials on the web.