Mixing source and bytecode. A case for compilation by normalization

Language extensions increase programmer productivity by providing concise, often domain-specific syntax, and sup-port for static verification of correctness, security, and style constraints. Language extensions can often be realized through translation to the base language, supported by pre-processors and extensible compilers. However, various kinds of extensions require further adaptation of a base compiler’s internal stages and components, for example to support sep-arate compilation or to make use of low-level primitives of the platform (e.g., jump instructions or unbalanced synchro-nization). To allow for a more loosely coupled approach, we propose an open compiler model based on normalization steps from a high-level language to a subset of it, the core language. We developed such a compiler for a mixed Java and (core) bytecode language, and evaluate its effective-ness for composition mechanisms such as traits, as well as statement-level and expression-level language extensions