Combinators
Robert Widmann’s category-theoretic overview of monads
Robert Widmann’s implementation of the continuation monad in Swift
A Swift Continuation Monad · GitHub
A Type System from Scratch
Programming is Mathematics
This is why I respect the Functional Programming movement: they get it. Functional Programmers understand that (at a minimum) 50 years of research and refinement is a pretty good thing to stake your data types on. Stick to actual mathematics. You'll have to learn it eventually, you may as well not cloud your own thinking in the process. Mathematics is the simplest and most precise language mankind has ever invented, and you should be able to speak it.