It's not intuitive, but it's straightforward once you understand the semantics. There are basically two cases. Case 1:

    x <- monadicFunctionA
    monadicFunctionB

is rewritten as:

    monadicFunctionA >>= \x -> monadicFunctionB

The important thing here is that x is just the variable name in an lambda expression that you don't see. Case 2:

    monadicFunctionA
    monadicFunctionB

is rewritten as:

    monadicFunctionA >> monadicFunctionB

Where >> === >>= \_ ... . Given these rules, you can approximate do-notation like so:

    monadicFunctionA >>=
    \x -> monadicFunctionB >>
    monadicFunctionC ...