- predicates->comparator type-predicate compare-predicateprocedure
Returns a comparator that invokes type-predicate on its first and its second arguments. If they both return #t, then they are assumed to be of the same type, and compare-predicate is invoked on the first and second arguments together. If the result is #t or #f, then the comparator returns #t or #f respectively. If they are not of the same type, a third value is returned. The comparator always ignores its third argument.