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ICFP 2019
Sun 18 - Fri 23 August 2019 Berlin, Germany
Wed 21 Aug 2019 14:37 - 15:00 at Aurora Borealis - Modal Types Chair(s): Dominique Devriese

In programming, some data acts as a resource (e.g., file handles, channels) subject to usage constraints. This poses a challenge to software correctness as most languages are agnostic to constraints on data. The approach of linear types provides a partial remedy, delineating data into resources to be used but never copied or discarded, and unconstrained values. Bounded Linear Logic provides a more fine-grained approach, quantifying non-linear use via an indexed-family of modalities. Recent work on coeffect types generalises this idea to graded comonads, providing type systems which can capture various program properties. Here, we propose the umbrella notion of graded modal types, encompassing coeffect types and dual notions of type-based effect reasoning via graded monads. In combination with linear and indexed types, we show that graded modal types provide an expressive type theory for quantitative program reasoning, advancing the reach of type systems to capture and verify a broader set of program properties. We demonstrate this approach via a type system embodied in a fully-fledged functional language called Granule, exploring various examples.

Wed 21 Aug
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13:30 - 15:00: Research Papers - Modal Types at Aurora Borealis
Chair(s): Dominique DevrieseVrije Universiteit Brussel
icfp-2019-papers13:30 - 13:52
Daniel GratzerAarhus University, Jonathan SterlingCarnegie Mellon University, Lars BirkedalAarhus University
icfp-2019-papers13:52 - 14:15
Pierre-Marie PédrotINRIA, Nicolas TabareauInria, Hans FehrmannUniversity of Chile, Éric TanterUniversity of Chile & Inria Paris
icfp-2019-papers14:15 - 14:37
Patrick BahrIT University of Copenhagen, Christian Uldal GraulundIT University of Copenhagen, Rasmus Ejlers MøgelbergIT University of Copenhagen
icfp-2019-papers14:37 - 15:00
Dominic OrchardUniversity of Kent, UK, Vilem-Benjamin LiepeltUniversity of Kent, UK, Harley D. Eades IIIAugusta University