Wed 17 Jul 2019 14:30 - 14:50 at Mancy - Types Chair(s): Davide Ancona

The Julia programming language supports multiple dispatch and provides a rich type annotation language to specify method applicability. When multiple methods are applicable for a given call, Julia relies on subtyping between method signatures to pick the correct method to invoke. Julia’s subtyping algorithm is surprisingly complex, and determining whether it is correct remains an open question. In this paper, we focus on one piece of this problem: the interaction between union types and covariant tuples. Previous work normalized unions inside tuples to disjunctive normal form. However, this strategy has two drawbacks: complex type signatures induce space explosion, and interference between normalization and other features of Julia’s type system. In this paper, we describe the algorithm that Julia uses to compute subtyping between tuples and unions - an algorithm that is immune to space explosion and plays well with other features of the language. We prove this algorithm correct and complete against a semantic-subtyping denotational model in Coq.

Wed 17 Jul

Displayed time zone: Belfast change

13:30 - 15:10
TypesResearch Papers at Mancy
Chair(s): Davide Ancona University of Genova
13:30
20m
Research paper
Transient Typechecks are (Almost) Free
Research Papers
Richard Roberts Victoria University of Wellington, Stefan Marr University of Kent, Michael Homer Victoria University of Wellington, James Noble Victoria University of Wellington
DOI Media Attached
13:50
20m
Research paper
A Typing Discipline for Hardware Interfaces
Research Papers
Jan de Muijnck-Hughes University of Glasgow, Wim Vanderbauwhede University of Glasgow
DOI Media Attached
14:10
20m
Research paper
Minimal Session TypesPearl
Research Papers
Alen Arslanagić University of Groningen, Jorge A. Pérez University of Groningen, The Netherlands, Erik Voogd University of Groningen
DOI Media Attached
14:30
20m
Research paper
Julia's Efficient Algorithm for Subtyping Unions and Covariant TuplesPearl
Research Papers
Benjamin Chung Northeastern University, Francesco Zappa Nardelli Inria, Jan Vitek Northeastern University
DOI Media Attached
14:50
20m
Research paper
On Satisfiability of Nominal Subtyping with Variance
Research Papers
Aleksandr Misonizhnik Saint-Petersburg State University, Dmitry Mordvinov Saint-Petersburg State University, JetBrains Research
DOI Media Attached