StructPair<'a, 'b> Type
A struct-based representation of a pair. This type would seem redundant with struct (,) and KeyValuePair, but it's not. This type is unique in that allows you to take a reference to its Fst and Snd fields. Unfortunately, there seems to be no way to do that with struct (,) or KeyValuePair. NOTE: StructPair doesn't allow client assemblies to reference its fields, so it's not properly usable outside of Nu's engine code, unfortunately.