Dynamic Dependency-Based Purity Checking

Many software language tools use declarative domain-specific languages (DDSLs) to implement parts of their functionality, such as context-free grammars for parsing or inference rules for type analysis. For interoperability and ease of use, DDSLs often rely on embedded general-purpose language (GPL) code fragments, as in the semantic actions of parser specifications, but require that these GPL fragments fulfill certain semantic properties, such as the absence of observable side effects. Fulfilling these properties is usually up to the developer, and accidental violations can lead to subtle and hard-to-trace bugs.