Powerful and seamless syntax extensions on a statically typed language

Abstract

In this paper, we propose a mechanism of user-defined operators with better expressiveness while keeping composability. Our user-defined operators, named protean operators, can express arbitrary Parsing Expression Grammar (PEG) syntax, and they can also express complex user-defined literals. A library of user-defined operators is composable - the library can use with any other libraries. We have developed ProteaJ, which is an extension of Java 1.4 supporting protean operators.