High-performance language interoperability in multi-language runtimes

Programs often consist of parts that are written in different languages because sub-problems lend themselves to being implemented in a particular language. However, multi-language programs often suffer from poor performance, complex cross-language interfaces, or insufficient flexibility. We propose a novel approach for composing multiple language implementations in a seamless way. Foreign objects of one language can be used like regular objects in another language. Our interoperability mechanism targets language implementations that run on the same VM and have the same style of intermediate representation (IR), e.g., an abstract syntax tree (AST). For accessing foreign objects we generate foreign-language-specific IR patterns that we insert into the IR of the host application. Thus we avoid converting or marshalling foreign objects at the language border. Our mechanism also allows the just-in-time compiler of the host VM to inline and optimize across language borders.