[Haskell-cafe] Re: Bi-directional Maps

[Albert Y. C. Lai]

apfelmus wrote:
> Hugh Perkins wrote:
>> Arguably there are two possible implementations, one that enforces
>> one-to-one mapping, and one which allows multiple values, in either
>> direction.
> 
> Terminology reminder :)
> - the latter is called "(binary) relation"
>   http://en.wikipedia.org/wiki/Binary_relation
> - the former would be a "bijection"
>   http://en.wikipedia.org/wiki/Bijective_map

Following a great tradition,

"That's just semantics."