Blogs (1) >>
POPL 2019
Sun 13 - Sat 19 January 2019 Cascais, Portugal
Thu 17 Jan 2019 13:45 - 14:07 at Sala I - Type Inference I Chair(s): Michael Hicks

Bidirectional typechecking, in which terms either synthesize a type or are checked against a known type, has become popular for its applicability to a variety of type systems, its error reporting, and its ease of implementation. Following principles from proof theory, bidirectional typing can be applied to many type constructs. The principles underlying a bidirectional approach to indexed types (generalized algebraic datatypes) are less clear. Building on proof-theoretic treatments of equality, we give a declarative specification of typing based on focalization. This approach permits declarative rules for coverage of pattern matching, as well as support for first-class existential types using a focalized subtyping judgment. We use refinement types to avoid explicitly passing equality proofs in our term syntax, making our calculus similar to languages such as Haskell and OCaml. We also extend the declarative specification with an explicit rules for deducing when a type is principal, permitting us to give a complete declarative specification for a rich type system with significant type inference. We also give a set of algorithmic typing rules, and prove that it is sound and complete with respect to the declarative system. The proof requires a number of technical innovations, including proving soundness and completeness in a mutually recursive fashion.

Thu 17 Jan
Times are displayed in time zone: Greenwich Mean Time : Belfast change

13:45 - 14:51: Type Inference IResearch Papers at Sala I
Chair(s): Michael HicksUniversity of Maryland, College Park
13:45 - 14:07
Sound and Complete Bidirectional Typechecking for Higher-Rank Polymorphism with Existentials and Indexed Types
Research Papers
Jana DunfieldQueen's University, Kingston, Ontario, Neel KrishnaswamiComputer Laboratory, University of Cambridge
Link to publication DOI Media Attached
14:07 - 14:29
Abstracting Extensible Data Types; Or, Rows By Any Other Name
Research Papers
J. Garrett MorrisUniversity of Kansas, USA, James McKinna
Link to publication DOI Media Attached
14:29 - 14:51
Polymorphic Symmetric Multiple Dispatch with Variance
Research Papers
Gyunghee ParkKAIST, Oracle Labs, Jaemin HongKAIST, South Korea, Guy L. Steele Jr.Oracle Labs, Sukyoung RyuKAIST, South Korea
Link to publication DOI Media Attached File Attached