Lambda the Ultimate

Expression and Loop Libraries for High-Performance Code Synthesis. Christopher Mueller and Andrew Lumsdaine. LCPC2006.

To simultaneously provide rapid application development and high performance, developers of scientific and multimedia applications often mix languages, using scripting languages to glue together high-performance components written in compiled languages. While this can be a useful development strategy, it distances application developers from the optimization process while adding complexity to the development tool chain. Recently, we introduced the Synthetic Programming Environment (SPE) for Python, a library for generating and executing machine instructions at run-time.

The authors didn't show much interest yet in supporting the most widespread ISAs, those for Intel processors. Instead they focus on PowerPC but also Cell. Have fun with Python and PS3 hacking.

Edit: You might also checkout the site of Christopher Mueller containing related material.

Morphing: Safely Shaping a Class in the Image of Others, Shan Shan Huang, David Zook, and Yannis Smaragdakis. ECOOP 2007.

We present MJ: a language for specifying general classes whose members are produced by iterating over members of other classes. We call this technique “class morphing” or just “morphing”. Morphing extends the notion of genericity so that not only types of methods and fields, but also the structure of a class can vary according to type variables. This offers the ability to express common programming patterns in a highly generic way that is otherwise not supported by conventional techniques. For instance, morphing lets us write generic proxies (i.e., classes that can be parameterized with another class and export the same public methods as that class); default implementations (e.g., a generic do-nothing type, configurable for any interface); semantic extensions (e.g., specialized behavior for methods that declare a certain annotation); and more. MJ’s hallmark feature is that, despite its emphasis on generality, it allows modular type checking: an MJ class can be checked independently of its uses. Thus, the possibility of supplying a type parameter that will lead to invalid code is detected early—an invaluable feature for highly general components that will be statically instantiated by other programmers.

This is related to the paper by Turon and Reppy I linked to yesterday; it's another take on compile-time metaprogramming. This time they have a static iteration over the structure of a class, which makes their safety result rather impressive. I talked Huang, and she told me that their big-picture goal is to eventually build a full language for manipulating programs at compile time, while still preserving all the safety guarantees we expect.

Traditionally, languages have been designed to be viewed as black box abstractions; end programmers have no control overthe semantics or implementation of these abstractions. The CLOS MOP on the other hand, "opens up" the CLOS abstraction, and its implementation to the programmer. The programmer can, for example, adjust aspects of the implementation strategy such as instance representation, or aspects of the language semantics such as multiple inheritance behavior. The design of the CLOS MOP is such that this opening up does not expose the programmer to arbitrary details of the implementation, nor does it tie the implementor's hand unnecessarily -- only the essential structure of the implementation is exposed.

In more recent work, we have pushed the metaobject protocol idea in new directions, and we now believe that idea is not limited to its specific incarnation in CLOS, or to object-oriented languages, or to languages with a large runtime, or even to Lisp-like languages. Instead, we believe that providing an open implementation can be advantageous in a wide range of high-level languages and that metaobject protocol technology is a powerful tool for providing that power to the programmer.