A gentle introduction to semantic subtyping

Abstract

Subtyping relations are usually defined either syntactically by a formal system or semantically by an interpretation of types into an untyped denotational model. This work shows how to define a subtyping relation semantically in the presence of boolean connectives, functional types and dynamic dispatch on types, without the complexity of denotational models, and how to derive a complete subtyping algorithm. The presentation is voluntarily kept informal and discursive and the technical details are reduced to a minimum since we rather insist on the motivations, the intuition, and the guidelines to apply the approach. © Springer-Verlag Berlin Heidelberg 2005.