OneToOne

A data structure for one-to-one mapping between values. A 'OneToOne' is essentially a bijection between subsets of its two argument types.

Every first value is associated with exactly one second value and vice versa. Compare this to a Dict , where every key is associated with exactly one value, but a value can be associated with more than one key.

Internally, a OneToOne one is composed of two dictionaries, one for the first-to-second direction and one for second-to-first. As such, insert, remove, and query operations all have the same big-O performance as dictionaries.

import OneToOne exposing (OneToOne)

myOneToOne : OneToOne String Int
myOneToOne =
    OneToOne.empty
        |> OneToOne.insert "potato" 100
        |> OneToOne.insert "cabbage" 200
        |> OneToOne.insert "tomato" 300
        |> OneToOne.insert "tomato" 100

OneToOne.toList myOneToOne 
--> [ ( "cabbage", 200 ), ( "tomato", 100 ) ] 

Tests

This package uses elm-test and elm-verify-examples