Logo image
Back
Mixed Messages: Measuring Conformance and Non-Interference in TypeScript
Conference proceeding   Open access

Mixed Messages: Measuring Conformance and Non-Interference in TypeScript

Jack Williams, J. Garrett Morris, Philip Wadler and Jakub Zalewski
Leibniz International Proceedings in Informatics, LIPIcs, Vol.74, pp.281-2829
06/23/2017
DOI: 10.4230/lipics.ecoop.2017.28
url
https://doi.org/10.4230/lipics.ecoop.2017.28View
Published (Version of record) Open Access

Abstract

TypeScript participates in the recent trend among programming languages to support gradual typing. The DefinitelyTyped Repository for TypeScript supplies type definitions for over 2000 popular JavaScript libraries. However, there is no guarantee that implementations conform to their corresponding declarations.We present a practical evaluation of gradual typing for TypeScript. We have developed a tool for use with TypeScript, based on the polymorphic blame calculus, for monitoring JavaScript libraries and TypeScript clients against the TypeScript definition. We apply our tool, TypeScript TPD, to those libraries in the DefinitelyTyped Repository which had adequate test code to use. Of the 122 libraries we checked, 62 had cases where either the library or its tests failed to conform to the declaration. Gradual typing should satisfy non-interference. Monitoring a program should never change its behaviour, except to raise a type error should a value not conform to its declared type. However, our experience also suggests serious technical concerns with the use of the JavaScript proxy mechanism for enforcing contracts. Of the 122 libraries we checked, 22 had cases where the library or its tests violated non-interference.
 Computer Science

Details

Metrics

20 Record Views
Logo image