Kawa - Compiling Dynamic Languages to the Java VM Per Bothner Cygnus Solutions 1325 Chesapeake Terrace Sunnyvale CA 94089, USA <
[email protected]> Abstract: in a project in conjunction with Java. A language im- plemented on top of Java gives programmers many of Many are interested in Java for its portable bytecodes the extra-linguistic benefits of Java, including libraries, and extensive libraries, but prefer a different language, portable bytecodes, web applets, and the existing efforts especially for scripting. People have implemented other to improve Java implementations and tools. languages using an interpreter (which is slow), or by translating into Java source (with poor responsiveness The Kawa toolkit supports compiling and running vari- for eval). Kawa uses an interpreter only for “simple” ous languages on the Java Virtual Machine. Currently, expressions; all non-trivial expressions (such as function Scheme is fully supported (except for a few difficult fea- definitions) are compiled into Java bytecodes, which are tures discussed later). An implementation of ECMA- emitted into an in-memory byte array. This can be saved Script is coming along, but at the time of writing it is for later, or quickly loaded using the Java ClassLoader. not usable. Kawa is intended to be a framework that supports mul- Scheme [R RS] is a simple yet powerful language. It tiple source languages. Currently, it only supports is a non-pure functional language (i.e. it has first-class Scheme, which is a lexically-scoped language in the Lisp functions, lexical scoping, non-lazy evaluation, and side family. The Kawa dialect of Scheme implements almost effects).