A prototype-based approach to object reclassification

TL;DR

This paper introduces a new calculus for prototype-based object languages that ensures safe self-extension and message handling through a sound type system, blending static safety with dynamic flexibility.

Contribution

It presents a novel calculus with a sound type system for prototype-based languages that guarantees message safety during object self-extension.

Findings

The calculus guarantees no message-not-found runtime errors.

It combines static type safety with dynamic language flexibility.

The type system is sound for the proposed object calculus.

Abstract

We investigate, in the context of functional prototype-based lan- guages, a calculus of objects which might extend themselves upon receiving a message, a capability referred to by Cardelli as a self-inflicted operation. We present a sound type system for this calculus which guarantees that evaluating a well-typed expression will never yield a message-not-found runtime error. The resulting calculus is an attempt towards the definition of a language combining the safety advantage of static type checking with the flexibility normally found in dynamically typed languages.