> For this the key/value pair constructor for Dictionary would be the better 
> option, since the .map() method essentially already lets you do this. Adding 
> key transformation to .mapValues() would only make it less specialised (it’s 
> called .mapValues after all ;), plus it would be incompatible with any 
> simultaneous/future lazy implementation since you can’t just transform the 
> keys lazily (you also need a way to transform them back if you intend to use 
> them for lookups).

He was suggesting the transform be of type (Key, Value) -> NewValue; that is, 
it would be able to see what the key was, but it wouldn't be able to transform 
the key.

-- 
Brent Royal-Gordon
Architechies

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