bimap is:package

package bimap
Uses
Bidirectional mapping between two key types A data structure representing a bidirectional mapping between two key types. Each value in the bimap is associated with exactly one value of the opposite type.
package bimaps
Uses
bijections with multiple implementations. Bijections between sets of values.
package bimap-server
Uses
Not on Stackage, so not searched. Two-column database server.