[skybrian]

This explanation doesn't contain any practical examples either. I mean, I do know that Promises are a monad, but that's not obviously helpful. You can write plenty of async code using Promises without knowing that, and it will probably be clearer to the reader. Similarly, options are a monad, but that's unhelpful for writing code that deals with optional values.

Why is most writing about functional programming like this?

[kadoban]

The practical example is being able to use the same names and utility functions and such on all of the different monads. That's kind of it.

Other than that it's just nice for communication in the right groups, it's shorthand for a whole bunch of properties that you then don't have to explain.

It also only really works super well in languages where the type system is expressive enough to allow that (or just permissive enough not to stop you I guess), so that mostly comes up in fun "functional" languages where they spent a bunch of time on the type system.

You'll probably understand a bit better if you take some time and learn/use Haskell a bit (if you don't already understand, it kind of sounds like you do tbh). It's a fun and educational language in a bunch of ways IMO. It depends on the kind of person/programmer you are if you'll really care though.

[tmtvl]

Because FP is useless so there aren't any practical examples. ...but all kidding aside, I kinda feel like an astronomer talking to an astrologer when it comes to this stuff. Like I'm scanning the night sky with my telescope while he's talking about Mars being 'in the house of Jupiter' or whatever. It's the old Abelson quote about computer science all over again.