Abstract:
Existing approaches to object encapsulation either rely on ad hoc syntactic restrictions or
require the use of specialised type systems. Syntactic restrictions are difficult to scale and
to prove correct, while specialised type systems require extensive changes to programming
languages. We demonstrate that confinement can be enforced cheaply in Featherweight
Generic Java, with no essential change to the underlying language or type system. This
result demonstrates that polymorphic type parameters can simultaneously act as ownership
parameters and should facilitate the adoption of confinement and ownership type systems in
general-purpose programming languages.
