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ROTOR : A Tool for Renaming Values in OCaml's Module System

Rowe, Reuben, Férée, Hugo, Thompson, Simon, Owens, Scott (2019) ROTOR : A Tool for Renaming Values in OCaml's Module System. In: 2019 IEEE/ACM 3rd International Workshop on Refactoring (IWoR). . pp. 27-30. IEEE Press ISBN 978-1-72812-271-7. E-ISBN 978-1-72812-270-0. (doi:10.1109/IWoR.2019.00013) (KAR id:80338)


The functional programming paradigm presents its own unique challenges to refactoring. For the OCaml language in particular, the expressiveness of its module system makes this a highly non-trivial task and there is currently no automated support for large-scale refactoring in the OCaml language.

We present Rotor, a tool for automatically renaming top-level value definitions in OCaml's module system. To compute the effect of renaming, Rotor relies on a novel concept which we call a value extension. This is a collection of related declarations in a program that must all be renamed at once. In practice, this leads to a notion of dependency: renaming a function foo in module A (mutually) depends on renaming function foo in module B etc.

We describe important aspects of Rotor's design, implementation, and evaluation on two large codebases: Jane Street's core library and its dependencies, and the OCaml compiler itself. In these real-world settings we find that some cases involve a surprisingly complex network of dependencies, and that the use of the PPX preprocessor system presents significant challenges.

Item Type: Conference or workshop item (Paper)
DOI/Identification number: 10.1109/IWoR.2019.00013
Projects: Trustworthy Refactoring
Subjects: Q Science > QA Mathematics (inc Computing science) > QA 76 Software, computer programming,
Divisions: Divisions > Division of Computing, Engineering and Mathematical Sciences > School of Computing
Funders: Engineering and Physical Sciences Research Council (
Depositing User: S. Thompson
Date Deposited: 03 Mar 2020 10:31 UTC
Last Modified: 04 Mar 2024 19:21 UTC
Resource URI: (The current URI for this page, for reference purposes)

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