Reasoning about hierarchies of online program specialization systems

Abstract

We present the language S-Graph-n the core of a multilevel metaprogramming environment for exploring foundational issues of serf-applicable online program specialization. We illustrate how special-purpose S-Graph-n primitives can be used to obtain an efficient and conceptually simple encoding of programs as data objects. The key feature of the encoding scheme is the use of numerical indices which indicate the number of times that a program piece has been encoded. Evaluation of S-Graph-n is formalized via an operational semantics. This semantics is used to justify the fundamental operations on metavariables special-purpose tags for tracking unknown values in self-applicable online specialization systems. We show how metavariables can be used to construct biased generating extensions without relying on a separate binding-time analysis phase.