A TRAVERSABLE[E_] is a finite readable sequence of objects of type E_. For instance, COLLECTIONs and STRINGs are TRAVERSABLE.

A good performance should always be obtained by sequentially accessing a TRAVERSABLE with increasing indexes (from lower to upper), as demonstrated in the following code snippet :

 from
    i := a_traversable.lower
 until
    i > a_traversable.upper
 loop
    do_something_with(a_traversable.item(i))
    i := i + 1
 end

Other accessing methods (including random access and sequential access from upper to lower) may or may not lead to acceptable performance, depending on the particular implementation of TRAVERSABLE.