I support your work on this -- I've always wanted to see a full-length book exploring monads, and will definitely read it when it comes out. (Unfortunately I don't have time to review chapters right now.)

One suggestion: you might also want to discuss arrows/bolts, which are a generalization of monads: see https://en.wikipedia.org/wiki/Arrow_(computer_science) The Fudgets library in Haskell is a good example of the value of this abstraction.