Unlike F# or any other decent functional language, JavaScript doesn't have very good constructs to guide and ensure the programmer is using these constructs properly, let alone using alongside with existing error propagating constructs.
Javascript has at least two mature type checkers you can use that will let you use these constructs just as safely as in F#.
What happens when you mix these with promises
In my either library I added rightMapThen and leftMapThen, and called it a day. worked absolutely fine. I think I also have rightFlatMapThen and leftFlatMapThen. Works flawlessly, and I have everything I enjoyed about the equivalent in F# (where I first encountered the concept).
Javascript has at least two mature type checkers you can use that will let you use these constructs just as safely as in F#.
What happens when you mix these with promises
In my either library I added rightMapThen and leftMapThen, and called it a day. worked absolutely fine. I think I also have rightFlatMapThen and leftFlatMapThen. Works flawlessly, and I have everything I enjoyed about the equivalent in F# (where I first encountered the concept).