In functional languages, recursive data structures are often most naturally walked with recursive functions. Languages like Haskell and ML take this to its natural conclusion and use it systematically. For example, a linked list. Here's how the Haskell "last" function, to get the last item in a linked list, is implemented in the standard library:

    last [x]                =  x
    last (_:xs)             =  last xs
    last []                 =  errorEmptyList "last"

If given a list with a single item, return that item. If given a list with two or more items, call itself with the list minus its head. If given an empty list, throw an error.