Per Bothner

Biography

Per Bothner has a Cand.Scient. degree from Oslo, Norway, and a Ph.D. from Stanford (1988). He worked for Cygnus Solutions 1991-1999 on the GNU compiler, debugger, and run-time libraries. He was the technical leader of Cygnus's Java group from it was formed, and Gcj (the "GNU Compiler for the Java platform") is based on his ideas (and to some extent his code). Per currently works on agents for web browsing, for an as-yet-unnamed spin-off from The Portola Group. Per is the author of a number of free software utilities, including the Emacs terminal emulator "term", the Linux stdio implementation, and the Kawa compiled-Scheme-in-Java system.

Abstract: Functional Scripting Languages for the JVM

Scripting languages are useful in a Java context because they are easier to use, partly because they provide "eval." Lisp-like functional languages like Scheme also provide higher-level abstractions, syntactic extension, and powerful composition mechanisms. Kawa is a Java environment for Scheme and similar languages. Unlike most scripting languages for Java, it compiles source code to Java bytecodes, yet by using the ClassLoader has full support for dynamic features such as "eval". The talk will discuss some of the issues in implementing high-level concepts (such as closures) using a relatively low-level language (Java). We will then discuss some current Kawa projects:

• Among the most requested Kawa features are object-oriented programming and modules. I will explain how to implement CLOS-style multiple inheritance using Java interfaces.
• A functional "transformer" maps "virtual" XML/HTML document into other documents. Transformers can be conveniently combined using function composition; such combinations are efficient thanks to the use of a SAX-like API. The result is a powerful "algebra" for working with documents.
• Another new project is to add support for other languages besides Scheme, concentrating on Emacs Lisp. Swing-based classes implement Buffer, Window, and similar Emacs types. The ultimate goal is "JEmacs", a modern Java-based Emacs re-implementation that can use existing elisp packages.