This is either the most important paper in Computer Science.... or a trivial side effect of representing function composition by string concatenation...
[A] a = A
[A] b = [[A]]
[A] [B] c = [A B]
[A] d = [A] [A]
[A] e =
[A] [B] f = [B] [A]
[[db]fbcabc[da]cfc]da
Vg vf gur cnenqbkvpny pbzovangbe.