Verifiable Composition of Language Extensions

Domain-specific languages offer a variety of advantages, but their implementation techniques have disadvantages that sometimes prevent their use in practice. Language extension offers a potential solution to some of these problems, but remains essentially unused in practice. It is our contention that the main obstacle to adoption is the lack of any assurance that the compiler composed of multiple independent language extensions will work without the need for additional modifications, or at all. We propose to solve this problem by requiring extensions to independently pass a composition test that will ensure that any such extensions can be safely composed without “glue code,” and we propose to demonstrate that interesting extensions are still possible that satisfy such a test.