PLY is a set of bash scripts that provides parsing functionality for macros that generate shell code. It was inspired by lex & yacc UNIX utilities used for compiler construction, and its function is analogous to the role of C preprocessor.
The XPS is a scalable platform for meta-programming and domain engineering. It provides a virtual machine, compiler, and runtime library that make it possible to efficiently develop, debug, and run programs based on XPL (eXtensible Programming Language)