mapKeys package:refined-containers

mapKeys f m applies f to each key of m and collects the results into a new map. For keys that were mapped to the same new key, the value is picked in an unspecified way.
mapKeys f m applies f to each key of m and collects the results into a new map. For keys that were mapped to the same new key, the value corresponding to the greatest of the original keys is retained.
mapKeys f m applies f to each key of m and collects the results into a new map. For keys that were mapped to the same new key, the value corresponding to the greatest of the original keys is retained.
mapKeysWith c f m applies f to each key of m and collects the results into a new map. For keys that were mapped to the same new key, c acts as the combining function for corresponding values.
mapKeysWith c f m applies f to each key of m and collects the results into a new map. For keys that were mapped to the same new key, c acts as the combining function for corresponding values.
mapKeysWith c f m applies f to each key of m and collects the results into a new map. For keys that were mapped to the same new key, c acts as the combining function for corresponding values.