Fundamentals of CS I (CS151 2001S) : Reference

reverse: reverse a list

Parametersl, a list
PurposeProduces a reversed version of l.
ProducesA new list, r, whose elements are the elements of l in reverse order.
PreconditionsOne parameter (verified).
l is a list (verified).
PostconditionsDoes not affect l.
The initial element of r is the last element of l, the next element of r is the penultimate element of l, and so on and so forth.
If any elements of l are lists, does not reverse them.
> (reverse ())
> (reverse (list 1 2 3))
(3 2 1)
> (define lists (list (list 'a 'b 'c) (list 1) (list 4 2 1 0)))
> lists
((a b c) (1) (4 2 1 0))
> (reverse 'a)
reverse: expects argument of type <proper list>; given a

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