Parametric Compositional Data Types

Patrick Bahr, Tom Hvitved

    Research output: Conference Article in Proceeding or Book/Report chapterBook chapterResearchpeer-review

    Abstract

    In previous work we have illustrated the benefits that compositional data types (CDTs) offer for implementing languages and in general for dealing with abstract syntax trees (ASTs). Based on Swierstra's data types à la carte, CDTs are implemented as a Haskell library that enables the definition of recursive data types and functions on them in a modular and extendable fashion. Although CDTs provide a powerful tool for analysing and manipulating ASTs, they lack a convenient representation of variable binders. In this paper we remedy this deficiency by combining the framework of CDTs with Chlipala's parametric higher-order abstract syntax (PHOAS). We show how a generalisation from functors to difunctors enables us to capture PHOAS while still maintaining the features of the original implementation of CDTs, in particular its modularity. Unlike previous approaches, we avoid so-called exotic terms without resorting to abstract types: this is crucial when we want to perform transformations on CDTs that inspect the recursively computed CDTs, e.g. constant folding.
    Original languageUndefined/Unknown
    Title of host publicationProceedings Fourth Workshop on Mathematically Structured Functional Programming
    EditorsJames Chapman, Paul Blain Levy
    Number of pages22
    Volume76
    PublisherOpen Publishing Association
    Publication date1 Feb 2012
    Pages3-24
    DOIs
    Publication statusPublished - 1 Feb 2012

    Keywords

    • Compositional Data Types
    • Abstract Syntax Trees
    • Haskell
    • Variable Binders
    • Parametric Higher-Order Abstract Syntax

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