Patrycja Balik | Searcharxiv

arXiv2026

Remarks on Algebraic Reconstruction of Types and Effects

In their 1991 paper "Algebraic Reconstruction of Types and Effects," Pierre Jouvelot and David Gifford presented a type-and-effect reconstruction algorithm based on an algebraic structure of effects. Their work is considered a milestone in the development of type-and-effect systems, and has inspired numerous subsequent works in the area of static analysis. However, unlike the later research it spawned, the original algorithm considered a language with higher-rank polymorphism, a feature which is challenging to implement correctly. In this note, we identify subtle bugs related to variable binding in their approach to this feature. We revisit their type system and reconstruction algorithm, and describe the discovered issues.

cs.PL↗

arXiv2025

Deciding not to Decide: Sound and Complete Effect Inference in the Presence of Higher-Rank Polymorphism

Type-and-effect systems help the programmer to organize data and computational effects in a program. While for traditional type systems expressive variants with sophisticated inference algorithms have been developed and widely used in programming languages, type-and-effect systems did not yet gain widespread adoption. One reason for this is that type-and-effect systems are more complex and the existing inference algorithms make compromises between expressiveness, intuitiveness, and decidability. In this work, we present an effect inference algorithm for a type-and-effect system with subtyping, expressive higher-rank polymorphism, and intuitive set-like semantics of effects. In order to deal with scoping issues of higher-rank polymorphism, we delay solving of effect constraints by transforming them into formulae of propositional logic. We prove soundness and completeness of our algorithm with respect to a declarative type-and-effect system. All the presented results have been formalized in the Rocq proof assistant, and the algorithm has been successfully implemented in a realistic programming language.

cs.PL↗