A list is not a monad — it’s just a container of values, ie. a functor. A monad is a data structure defines a computation in a specific context, and allows composing these in a sequential manner. For example, the Haskell IO monad is a computational context in which you can do input/output, and all of these IO operations are represented using a data structure of the type “IO <return_value>”.

For example, the function “readLine” has the type “IO String”, and represents a computation that reads a line from standard input and returns it as a string. At runtime, evaluating this value will result in the runtime system asking the user for some input, and at compile-time this is represented as the string (that the user enters at runtime) inside the IO monad.

Huh? List is very much a monad.

But I can't make sense of the definition of >>= for the list in Haskell, which is:

    xs >>= f = [y | x <- xs, y <- f x]

    [1,2,3] >>= return . (+1)

    > [1,-2,3] >>= (\x -> replicate (abs x) x)
    [1,-2,-2,3,3,3]

Is there a resource for this ? or good old intuition ?

Just remember Absolutely ANY design pattern / data structure can be a monad as long as you can get an internal value out of that abstraction and define a bind operator to compose monads together.

This rule tells it all:

  (>>=)            :: m a -> (a -> m b) -> m b

You can define the bind operator to do whatever you want, it just needs to follow the type signature above and be associative.