Computer Science Department
School of Computer Science, Carnegie Mellon University


Simple, Efficient Object Encoding using Intersection

Karl Crary

January 1999

Also appears as CMU-CS-FOX-99-01

Keywords: Object encodings, intersection types, type theory

I present a type-theoretic encoding of objects that interprets method dispatch by self-application (i.e., method functions are applied to the objects containing them) but still validates the expected subtyping relationships. The naive typing of self-application fails to validate the expected subtyping relationships because it is too permissive and allows application to similarly typed objects that are not self. This new encoding solves this problem by constraining methods to be applied only to self using existential and intersection types. Using this typing, I give a full account of objects including self types and method update. The typing constructs used in this encoding appear to be quite rich, but they may be axiomatized in a novel, restricted fashion that is metatheoretically simple.

20 pages

Return to: SCS Technical Report Collection
School of Computer Science homepage

This page maintained by