compiler designing evaluation functional interpeter lazy_bookmarks meta optimization optimizing partial partial_evaluation plt programming pypy specialization todescribe universita

My tags:

From Wikipedia, the free encyclopedia

Programming evaluation
Eager Lazy Partial Remote Short-circuit Strategy

In computing, partial evaluation is a technique for several different types of program optimization by specialization. The most straightforward application is to produce new programs which run faster than the originals but are guaranteed to behave in the same way. More advanced uses include compiling by partially evaluating an interpreter with the program to be compiled as its input; generating compilers by partially evaluating a partial evaluator with an interpreter for the source language concerned as its input; and finally generating a compiler-generator by partially evaluating a partial evaluator with itself as its input.

A computer program, prog, is seen as a mapping of input data into output data:

I_static, the static data, is the part of the input data known at compile time.

The partial evaluator transforms into by precomputing all static input at compile time. prog ^* is called the "residual program" and should run more efficiently than the original program. The act of partial evaluation is said to "residualize" prog to prog ^* .

Contents 1 Futamura projections 2 References 3 See also 4 External links

[edit] Futamura projections

A particularly interesting example of this, first described in the 1970s by Yoshihiko Futamura, is when prog is an interpreter for a programming language.

If I_static is source code designed to run inside said interpreter, then partial evaluation of the interpreter with respect to this data/program produces prog*, a version of the interpreter that only runs that source code, is written in the implementation language of the interpreter, does not require the source code to be resupplied, and runs faster than the original combination of the interpreter and the source. In this case prog* is effectively a compiled version of I_static.

This technique is known as the first Futamura projection, of which there are three:

1. Specializing an interpreter for given source code, yielding an executable
2. Specializing the specializer for the interpreter (as applied in #1), yielding a compiler
3. Specializing the specializer for itself (as applied in #2), yielding a tool that can convert any interpreter to an equivalent compiler

[edit] References

• Yoshihiko Futamura (1971). "Partial Evaluation of Computation Process – An Approach to a Compiler-Compiler". Systems, Computers, Controls 2 (5): 45–50. http://www.brics.dk/~hosc/local/HOSC-12-4-pp381-391.pdf.  Reprinted in Higher-Order and Symbolic Computation 12 (4): 381–391, 1999, with a foreword.
• Charles Consel and Olivier Danvy (1993). "Tutorial Notes on Partial Evaluation". Proceedings of the Twentieth Annual ACM Symposium on Principles of Programming Languages: 493–501. 

[edit] See also

• Run-time algorithm specialisation
• Memoization
• Strength reduction
• Smn theorem
• Template metaprogramming

[edit] External links

• Neil D. Jones, Carsten K. Gomard, and Peter Sestoft: Partial Evaluation and Automatic Program Generation (1993) Book, full text available online.
• partial-eval.org - a large "Online Bibliography of Partial Evaluation Research".
• 1999 ACM SIGPLAN Workshop on Partial Evaluation and Semantics-Based Program Manipulation (PEPM'99)
• C++ Templates as Partial Evaluation, 1999 ACM SIGPLAN Workshop on Partial Evaluation and Semantics-Based Program Manipulation (PEPM'99)
• C++ Templates as Partial Evaluation a different version including Catat (pdf)
• Applying Dynamic Partial Evaluation to dynamic, reflective programming languages