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

13:45 - 14:51: Research Papers - Type Inference I at Sala I
Chair(s): Michael HicksUniversity of Maryland, College Park
POPL-2019-Research-Papers13:45 - 14:07
Joshua DunfieldQueen's University, Kingston, Ontario, Neelakantan R. KrishnaswamiComputer Laboratory, University of Cambridge
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POPL-2019-Research-Papers14:07 - 14:29
J. Garrett MorrisUniversity of Kansas, USA, James McKinna
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POPL-2019-Research-Papers14:29 - 14:51
Gyunghee ParkKAIST, Oracle Labs, Jaemin HongKAIST, South Korea, Guy L. Steele Jr.Oracle Labs, Sukyoung RyuKAIST, South Korea
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