tests whether the provided forms are indexed sequences
(indexed? form+) (!indexed? form+) (is-indexed form)
If all forms evaluate to a valid sequence than can be accessed by index, then this function will return #t (true). The first non-indexed sequence will result in the function returning #f (false).
(indexed? '(1 2 3 4) [5 6 7 8])
This example will return #t (true).
Like most predicates, this function can also be negated by prepending the
! character. This means that all of the provided forms must not be valid indexed sequences.
(!indexed? "hello" 99)
This example will return #f (false) because strings are indexed sequences.