Implicit Staging of EDSL Expressions: A Bridge between Shallow and Deep Embedding

Abstract

Common implementation approaches for embedding DSLs in general-purpose host languages force developers to choose between a shallow single-staged embedding which offers seamless usage, but limits DSL developers, or a deep multi-staged embedding which offers freedom to optimize at will, but is less seamless to use and incurs additional runtime overhead. We propose a metaprogrammatic approach for extracting domain-specific programs from user programs for custom processing. This allows for similar optimization options as deep embedding, while still allowing for seamless embedded usage. We have implemented a simplified instance of this approach in a prototype framework for Java-embedded EDSL expressions, which relies on load-time reflection for improved deployability and usability.