Existential Owners for Ownership Types.
Tobias Wrigstad, Dave Clarke · The Journal of Object Technology · 2007
This paper describes a lightweight approach to adding run-time checked downcasts to a language in the presence of ownership types without the need for a run-time representation of owners.Previous systems [6] have required owners of objects to be tracked and matched at run-time which is costly in terms of memory and performance.Our proposal avoids run-time overhead to deal with owners and also extends the expressiveness of ownership-based systems enough to handle the Java equals idiom for structural equality comparison.The price is that it is sometimes impossible to downcast a type into a type that can be statically aliased.Our proposal is completely orthogonal and combinable with previous work.