The symbol ‘⇒’ in program examples is read “evaluates to”. For example,
(* 5 8) ⇒ 40
means that the expression (* 5 8) evaluates to the object
40. Or, more precisely: the expression given by the sequence of
characters ‘(* 5 8)’ evaluates, in an environment containing the
base library, to an object that can be represented externally by the
sequence of characters ‘40’. For a discussion of external
representations of objects, see External representations.