Skins as a Mechanism for Makin Languages Syntactically Extensible

Abstract

This paper introduces the skin mechanism for extending programming language syntax. A skin associates an encapsulated collection of syntax rules to semantic handlers. These syntax rules are declared all at once and used exclusively so syntax conflicts and ambiguities can be avoided. The semantic handlers can thus be reused freely. Metaobject protocol is used as the semantic handing facility. It has access to meta-level information about the user program so advanced program transformations can be done. Extended examples are given, and a summary shows the methodology for designing and implementing a skin mechanism.