sorted-map-by

(sorted-map-by comparator k v ...)

clojure.core/sorted-map-by: a sorted map ordered by comparator, a function of two keys read like the oracle's: a number orders by its integer part's sign (compare, (- a b); 0.5 is equal), true puts the first key before the second and false asks the reversed call (<, >). Keys it calls equal are one key. Every verb keeps the comparator. The keys are not checked the way sorted-map checks them, and anything but a function as the comparator signals. As a value a function of a comparator and pairs.