Substructural Parametricity

Fuente: arXiv
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Hauptverfasser: Aberlé, C. B., Martens, Chris, Pfenning, Frank
Format: Preprint
Veröffentlicht: 2025
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author Aberlé, C. B.
Martens, Chris
Pfenning, Frank
author_facet Aberlé, C. B.
Martens, Chris
Pfenning, Frank
contents Ordered, linear, and other substructural type systems allow us to expose deep properties of programs at the syntactic level of types. In this paper, we develop a family of unary logical relations that allow us to prove consequences of parametricity for a range of substructural type systems. A key idea is to parameterize the relation by an algebra, which we exemplify with a monoid and commutative monoid to interpret ordered and linear type systems, respectively. We prove the fundamental theorem of logical relations and apply it to deduce extensional properties of inhabitants of certain types. Examples include demonstrating that the ordered types for list append and reversal are inhabited by exactly one function, as are types of some tree traversals. Similarly, the linear type of the identity function on lists is inhabited only by permutations of the input. Our most advanced example shows that the ordered type of the list fold function is inhabited only by the fold function.
format Preprint
id arxiv_https___arxiv_org_abs_2503_03153
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Substructural Parametricity
Aberlé, C. B.
Martens, Chris
Pfenning, Frank
Logic in Computer Science
Programming Languages
Ordered, linear, and other substructural type systems allow us to expose deep properties of programs at the syntactic level of types. In this paper, we develop a family of unary logical relations that allow us to prove consequences of parametricity for a range of substructural type systems. A key idea is to parameterize the relation by an algebra, which we exemplify with a monoid and commutative monoid to interpret ordered and linear type systems, respectively. We prove the fundamental theorem of logical relations and apply it to deduce extensional properties of inhabitants of certain types. Examples include demonstrating that the ordered types for list append and reversal are inhabited by exactly one function, as are types of some tree traversals. Similarly, the linear type of the identity function on lists is inhabited only by permutations of the input. Our most advanced example shows that the ordered type of the list fold function is inhabited only by the fold function.
title Substructural Parametricity
topic Logic in Computer Science
Programming Languages
url https://arxiv.org/abs/2503.03153