Relative Effect Declarations for Lightweight Effect-Polymorphism

Type-and-effect systems are a well-studied approach for reasoning about the computational behavior of programs. A major roadblock in adopting effect systems in popular languages is the tradeoff between expressiveness and verbosity. In this technical report, we present a syntactically lightweight but expressive system for annotating effect-polymorphic behavior of functions. The presented system is independent from any specific effect domains and can be embedded in an extensible type-and-effect system.