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Title Gradual Indexed Inductive Types
Authors Stefan Malewski, Kenji Maillard, Nicolas Tabareau, Éric Tanter
Publication date August 2024
Abstract Indexed inductive types are essential in dependently-typed
programming languages, enabling precise and expressive specifications of
data structures and properties. Recognizing that programming and proving
with dependent types could benefit from the smooth integration of static and
dynamic checking that gradual typing offers, recent efforts have studied
gradual dependent types. Gradualizing indexed inductive types however
remains mostly unexplored: the standard encodings of indexed inductive types
in intensional type theory, e.g., using type-level fixpoints or subset
types, break in the presence of gradual features; and previous work on
gradual dependent types focus on very specific instances of indexed
inductive types. This paper contributes a general framework, named PUNK,
specifically designed for exploring the design space of gradual indexed
inductive types. PUNK is a versatile framework, enabling the exploration of
the space between eager and lazy cast reduction semantics that arise from
the interaction between casts and the inductive eliminator, allowing them to
coexist and interoperate in a single system. Our work provides significant
insights into the intersection of dependent types and gradual typing, by
proposing a criteria for well-behaved gradual indexed inductive types,
systematically addressing the outlined challenges of integrating these
types. The contributions of this paper are a step forward in the quest for
making gradual theorem proving and gradual dependently-typed programming a
reality.
Pages 544-572
Volume 8
Journal name Proceedings of the ACM Programming Languages
Publisher ACM Press (New York, NY, USA)
Reference URL View reference page