intervalApplication

A value that applies a reading to a map of intervals and does nothing after — x -> (..8: solid; 8..: dashed), y * 2 -> (..<0: red; otherwise: teal) — as that reading and the intervals the map's keys span. What a look that follows a reading changes at: nowhere but where the reading crosses an end. Null for a value that applies anything else, or a map keyed by names.