Why require Ord on map and mapR?

[karljs]

Sorry if I'm missing something obvious, but why do you have the Ord constraint on map and mapR?

[joelwilliamson]

Data.Map.mapKeys has an Ord constraint.

[joelwilliamson]

To expand, a Bimap is a pair of maps, one from a to b, and the other from b to a. Whenever a key or value type is changed, it must have an Ord constraint for the map keyed on that type to work.

[karljs]

Thanks, I understand. I was thinking, stupidly, that you wouldn't need to map across the keys for some reason since you store both maps.