The Problem of Structural Type Tests in a Gradual-Typed Language
John Boyland · 2014
The Grace programming language includes structural type tests and gradual typing. We demonstrate that this combination results in a mismatch. In particular, structural type tests (but not structural type assertions) can cause programs to give different results after typing annotations are added. We review the current uses of type tests in Grace programs and propose potential ways forward, all of which have their own drawbacks.