Guy L. Steele

Growing a language

Most of the time, I do not read my talks; I plan the main points and then speak off the top of my head. For this talk, I need to stick to a text, and for good cause. Please bear with me. I think you know what a man is. A woman is more or less like a man, but not of the same sex. (This may seem like a strange thing for me to start with, but soon you will see why.) Next, I shall say that a person is a woman or a man (young or old). To keep things short, when I say “he” I mean “he or she,” and when I say “his” I mean “his or her.” A machine is a thing that can do a task with no help, or not much help, from a person. (As a rule, we can speak of two or more of a thing if we add an “s” or “z” sound to the end of a word that names it.)

Parallel programming and parallel abstractions in Fortress

Summary form only given. The Programming Language Research Group at Sun Microsystems Laboratories seeks to apply lessons learned from the Java (TM) programming language to the next generation of programming languages. The Java language supports platform-independent parallel programming with explicit multithreading and explicit locks. As part of the DARPA program for High Productivity Computing Systems, we are developing Fortress, a language intended to support large-scale scientific computation. One of the design principles is that parallelism be encouraged everywhere (for example, it is intentionally just a little bit harder to write a sequential loop than a parallel loop). Another is to have fairly rich mechanisms for encapsulation and abstraction; the idea is to have a fairly complicated language for library writers that enable them to write libraries that present a relatively simple set of interfaces to the application programmer. We will discuss ideas for using a rich polymorphic type system to organize multithreading and data distribution on large parallel machines. The net result is similar in some ways to data distribution facilities in other languages such as HPF and Chapel, but more open-ended, because in Fortress the facilities are defined by user-replaceable libraries rather than wired into the compiler.

Integrating coercion with subtyping and multiple dispatch

Coercion can greatly improve the readability of programs, especially in arithmetic expressions. However, coercion interacts with other features of programming languages, particularly subtyping and overloaded functions and operators, in ways that can produce surprising behavior. We study examples of such surprising behavior in existing languages. This study informs the design of the coercion mechanism of Fortress, an object-oriented language with multiple dynamic dispatch, multiple inheritance and user-defined coercion. We describe this design and show how its restrictions on overloaded declarations prevent ambiguous calls due to coercion.

Celebrating 40 years of language evolution: simula 67 to the present and beyond

Simula 67 (SIMple Universal LAnguage 67) is considered by many as one of the earliest - if not the first - object-oriented language. Simula 67 was developed by Ole-Johan Dahl and Kristen Nygaard in Oslo, Norway and has greatly influenced object-oriented language development over the past 40 years. This panel brings together leading programming language innovators to discuss and debate past, present, and future language evolutions.