Proof of the principal type property for system O

We study a minimal extension of the Hindley/Milner system that supports overloading and polymorphic records. We also show that every typable term in this system has a principal type and give an algorithm to reconstruct that type. We give the proofs for termination, soundness and correctness for the constrained unification and the type reconstruction algorithm

Fighting bit Rot with Types (Experience Report: Scala Collections)

We report on our experiences in redesigning Scala\u27s collection libraries, focussing on the role that type systems play in keeping software architectures coherent over time. Type systems can make software architecture more explicit but, if they are too weak, can also cause code duplication. We show that code duplication can be avoided using two of Scala\u27s type constructions: higher-kinded types and implicit parameters and conversions

Type inference with constrained types

In this paper we present a general framework HM(X) for Hindley/Milner style type systems with constraints, analogous to the CLP(X) framework in constrained logic programming. We present sufficient conditions on the constraint domain X so that the principal types property carries over to HM(X). The conditions turn out to be fairly simple and natural. The usage of the aproach is demonstrated in instantion of parameter X with several known type disciplines. We consider extensible records, typeclasses, overloading and subtyping

A second look at overloading

We study a minimal extension of the Hindley/Milner system that supports overloading and polymorphic records. We show that the type system is sound with respect to a standard untyped compositional semantics. We also show that every typable term in this system has a principal type and give an algorithm to reconstruct that type

A second look at overloading

We study a minimal extension of the Hindley/Milner system that supports overloading and polymorphic records. We show that the type system is sound with respect to a standard untyped compositional semantics. We also show that every typable term in this system has a principal type and give an algorithm to reconstruct that type

Degrees of Separation: A Flexible Type System for Data Race Prevention

Data race is a notorious problem in parallel programming. There has been great research interest in type systems that statically prevent data races. Despite the progress in the safety and usability of these systems, lots of existing approaches enforce strict anti-aliasing principles to prevent data races. The adoption of them is often intrusive, in the sense that it invalidates common programming patterns and requires paradigm shifts. We propose Capture Separation Calculus (System CSC), a calculus based on Capture Calculus (System CC<:box), that achieves static data race freedom while being non-intrusive. It allows aliasing in general to permit common programming patterns, but tracks aliasing and controls them when that is necessary to prevent data races. We study the formal properties of System CSC by establishing its type safety and data race freedom. Notably, we establish the data race freedom property by proving the confluence of its reduction semantics. To validate the usability of the calculus, we implement it as an extension to the Scala 3 compiler, and use it to type-check the examples