I am also proposing to change the organization of the existing presentation as follows:

• first introduce bind and return but not the infix version (>>=)
• go through the first two examples of monads using only bind and return
• add a new section discussing the custom syntax let* x = e1 in e2 for bind e1 (fun x -> e2) and also the infix operator (>>=), drawing an explicit analogy between (>>=) and (|>) and explaining that the choice of when to use (>>=) vs let* is similar to the choice between let x = e1 in e2 and e1 |> e3 - if e3 is a lambda, then a let-binding may be clearer/easier to read.
• redo some of the previous examples using the new syntax
• present the third example using new syntax

The book currently presents the syntax for monads as

module type Monad = sig
  type 'a t
  val return : 'a -> 'a t
  val ( >>= ) : 'a t -> ('a -> 'b t) -> 'b t
end

I would like to surface for discussion the alternative proposal (from here https://ocaml.org/manual/5.3/bindingops.html)

module type Monad = sig
  type 'a t
  val return : 'a -> 'a t
  val ( let* ) : 'a t -> ('a -> 'b t) -> 'b t
  val ( and* ): 'a t -> 'b t -> ('a * 'b) t
end

The definition of (and*) is definable using let*, so it's not necessary, but you get the associated syntax sugar for parallel binds. In the following expression,

let* x = e1 and* y = e2 and* z = e3 in e4

all three bindings occur in parallel.

Just FYI I probably won't get time to review this PR until after the spring semester ends. Thank you though and feel free to update!

I will look into this later this summer when I'm considering what to do about #199.

This sounds good. This is only partially finished as I walked away from this after I had trouble getting the book to compile but I'll take another look at it.

@clarksmr You can feel free to ping me at the point in the summer when you want to address this structural rearrangement and ask me to do some of the legwork of rewriting, if you want to lay down the framework of the high level organizational structure.

@patrick-nicodemus #199 is now closed. You're welcome to proceed with adapting your revisions. I apologize for the conflicts!