Comparators compatible with SRFI 128.
(comparator-if<=> a b less equal greater)
(comparator-if<=> comparator a b less equal greater)
(make-comparator type-test equality ordering hash)
(comparator-test-type comparator obj)
(comparator-check-type comparator obj)
(comparator-hash comparator obj)
(=? comparator a b . #<undef>)
(<? comparator a b . #<undef>)
(>? comparator a b . #<undef>)
(<=? comparator a b . #<undef>)
(>=? comparator a b . #<undef>)
(make-pair-comparator car-comparator cdr-comparator)
(make-list-comparator element-comparator type-test empty? head tail)
(make-vector-comparator element-comparator type-test length ref)
(comparator-register-default! comparator)
(make-default-comparator)