[drumnerd]

A monad is not a container! It’s a way of composing functions if they have an effect. You tell how to inject a value in that effect (unit) and how to compose two functions that have that effect and that’s it: programmable semicolons.

[polygot]

Thanks for the feedback, I totally agree that monads are not containers. From an OOP perspective, they have some properties that make them, in some sense, sorta like containers, e.g., they contain a value like the Maybe monad. I still agree that they are not simply containers. I can clarify this in a revision to part 1 soon.

[lmm]

> From an OOP perspective, they have some properties that make them, in some sense, sorta like containers, e.g., they contain a value like the Maybe monad.

Not always! I find this is a big source of confusion; not all monads contain values, sometimes beginners think they can or should "get the value out" of a monad and that tends to lead to writing the wrong kind of code.

[mrkeen]

And in the article's case, 'have an effect' means 'be a list'.