Baking the Y Combinator from Scratch

> you technically can't do name = term

But you can do

    let name = term in term2

by de-sugaring it to

    ((λname. term2) term)

This is not relevant since this de-sugaring cannot be performed if `name` is recursive (i.e., if `term` refers to `name`), which `Y` is. So the author's derivation is still required in the pure lambda calculus.