- make-vector-comparatorprocedure
- type-test returns #t when type-test is #t and elements satisfy element-comparator.
- equality-predicate is #t when lengths of vectors are equal, and elements are equal according to element-comparator.
- ordering-predicate is #t when first vector length is less than second, or if equal, element-wise comparison is made.
- hash function of element-comparator computes hash of elements when are hashed together.