Making Int{Map,Set} polymorphic over the key type

Hi folks, What do you think about making IntMap and IntSet polymorphic over the keys as long as the key type k is Coercible to Int? The motivation is that oftentimes one needs to have a collection of newtype wrappers around Int, and then they have to either unpack/repack it around the relevant containers (which is not nice), or just use HashMap/HashSet (which is perhaps suboptimal). If this is a direction the community might deem reasonable, I'd be happy to work on this and make a PR to the containers repo (perhaps after discussing the specific details about naming, etc). -- Georg Rudoy