The last years have witnessed a flurry of new results in the area of partial evaluation. These tutorial notes survey the field and present a critical assessment of the state of the art. 1 Introduction Partial evaluation is a source-to-source program transformation technique for specializing programs with respect to parts of their input. In essence, partial evaluation removes layers of interpretation. In the most general sense, an interpreter can be defined as a program whose control flow is determined by its input data. As Abelson points out, [43, Foreword], even programs that are not themselves interpreters have important interpreter-like pieces. These pieces contain both compile-time and run-time constructs. Partial evaluation identifies and eliminates the compile-time constructs. 1.1 A complete example We consider a function producing formatted text. Such functions exist in most programming languages (e.g., format in Lisp and printf in C). Figure 1 displays a formatting functio...

Partial evaluators can be separated into two classes: offline specializers, which make all of their reduce/residualize decisions before specialization, and online specializers, which make such decisions during specialization. The choice of which method to use is driven by a tradeoff between the efficiency of the specializer and the quality of the residual programs that it produces. Existing research describes some of the inefficiencies of online specializers, and how these are avoided using offline methods, but fails to address the price paid in specialization quality. This paper motivates research in online specialization by describing two fundamental limitations of the offline approach, and explains why the online approach does not encounter the same difficulties.

We extend positive supercompilation to handle negative as well as positive information. This is done by instrumenting the underlying unfold rules with a small rewrite system that handles constraints on terms, thereby ensuring perfect information propagation. We illustrate this by transforming a naively specialised string matcher into an optimal one. The presented algorithm is guaranteed to terminate by means of generalisation steps.

This paper investigates the transformation of v -terms into continuation-passing style (CPS). We show that by appropriate j-expansion of Fischer and Plotkin's two-pass equational specification of the CPS transform, we can obtain a static and context-free separation of the result terms into "essential" and "administrative" constructs. Interpreting the former as syntax builders and the latter as directly executable code, we obtain a simple and efficient one-pass transformation algorithm, easily extended to conditional expressions, recursive definitions, and similar constructs. This new transformation algorithm leads to a simpler proof of Plotkin's simulation and indifference results. Further we show how CPS-based control operators similar to but more general than Scheme's call/cc can be naturally accommodated by the new transformation algorithm. To demonstrate the expressive power of these operators, we use them to present an equivalent but even more concise formulation of t...

This paper describes the transformation of lambda-terms from continuation-passing style (CPS) to direct style. This transformation is the left inverse of Plotkin's left-to-right call-by-value CPS encoding for the pure lambda-calculus. Not all -terms are CPS terms, and not all CPS terms encode a left-to-right call-by-value evaluation. These CPS terms are characterized here; they can be mapped back to direct style. In addition, the two transformations -- to continuation-passing style and to direct style -- are factored using a language where all intermediate values are named and their computation is sequentialized. The issue of proper tail-recursion is also addressed.

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This paper gives a gentle introduction to Turchin's supercompilation and its applications in metacomputation with an emphasis on recent developments. First, a complete supercompiler, including positive driving and generalization, is defined for a functional language and illustrated with examples. Then a taxonomy of related transformers is given and compared to the supercompiler. Finally, we put supercompilation into the larger perspective of metacomputation and consider three metacomputation tasks: specialization, composition, and inversion.

Security-typed languages enforce secrecy or integrity policies by type-checking. This paper investigates continuation-passing style (CPS) as a means of proving that such languages enforce noninterference and as a rst step towards understanding their compilation. We present a low-level, secure calculus with higher-order, imperative features and linear continuations.

We present a functional interpretation of classical linear logic based on the concept of linear continuations. Unlike their non-linear counterparts, such continuations lead to a model of control that does not inherently impose any particular evaluation strategy. Instead, such additional structure is expressed by admitting closely controlled copying and discarding of continuations. We also emphasize the importance of classicality in obtaining computationally appealing categorical models of linear logic and propose a simple "coreflective subcategory " interpretation of the modality "!". 1 Introduction In recent years, there has been considerable interest in applications of Girard's Linear Logic (LL) [Gir87] to programming language design and implementation. Over time, various more or less mutated versions of the original system have been proposed, but they all share the same basic premise: that assumptions made in the course of a formal proof can not necessarily be used an arbitrary n...

Our results formalize and confirm a folklore theorem about traditional bindingtime analysis, namely that CPS has a positive effect on binding times. What may be more surprising is that the benefit does not arise from a standard refinement of program analysis, as, for instance, duplicating continuations.