Advice is a mechanism, widely used in aspect-oriented languages, that allows one program component to augment or modify the behavior of other components. When advice and other components are composed together they become tightly coupled, sharing both control and data flows. However this creates important problems: modular reasoning about a component becomes very difficult; and two tightly coupled components may interfere with each other’s control and data flows. This paper presents EffectiveAdvice, a disciplined model of advice, inspired by Aldrich’s Open Modules, that has full support for effects. With EffectiveAdvice, equivalence of advice, as well as base components, can be checked by equational reasoning. The paper describes EffectiveAdvice as a Haskell library in which advice is modeled by mixin inheritance and effects are modeled by monads. Interference patterns previously identified in the literature are expressed as combinators. Parametricity, together with the com...
Bruno C. d. S. Oliveira, Tom Schrijvers, William R