Crossover: Towards Compiler-Enabled COBOL-C Interoperability

Interoperability across software languages is an important practical topic. In this paper, we take a deep dive into investigating and tackling the challenges involved with achieving interoperability between C and BabyCobol. The latter is a domain-specific language condensing challenges found in compiling legacy languages - borrowing directly from COBOL's data philosophy. Crossover, a compiler designed specifically to showcase the interoperability, exposes details of connecting a COBOL-like language with PICTURE clauses and re-entrant procedures, to C with primitive types and struct composites. Crossover features a C library for overcoming the differences between the data representations native to the respective languages. We illustrate the design process of Crossover and demonstrate its usage to provide a strategy to achieve interoperability between legacy and modern languages. The described process is aimed to be a blueprint for achievable interoperability between full-fledged COBOL and modern C-like programming languages.