Semantics-Based Compiling: A Case Study in Type-Directed Partial Evaluation

Abstract

We illustrate a simple and effective solution to semantics-based compiling. Our solution is based on type-directed partial evaluation, where• our compiler generator is expressed in a few lines, and is efficient;• its input is a well-typed, purely functional definitional interpreter in the manner of denotational semantics; • the output of the generated compiler is three-address code, in the fashion and efficiency of the Dragon Book; • the generated compiler processes several hundred lines of source code per second.The source language considered in this case study is imperative, blockstructured, higher-order, call-by-value, allows subtyping, and obeys stack discipline. It is bigger than what is usually reported in the literature on semantics-based compiling and partial evaluation. Our compiling technique uses the first Futamura projection, i.e., we compile programs by specializing a definitional interpreter with respect to this program.Our definitional interpreter is completely straightforward, stackbased, and in direct style. In particular, it requires no clever staging technique (currying, continuations, binding-time improvements, etc.), nor does it rely on any other framework (attribute grammars, annotations, etc.) than the typed λ-calculus. In particular, it uses no other program analysis than traditional type inference.The overall simplicity and effectiveness of the approach has encouraged us to write this paper, to illustrate this genuine solution to denotational semantics-directed compilation, in the spirit of Scott and

Online Type-Directed Partial Evaluation

“…Altenkirch, Hofmann and Streicher, andČubrić, Dybjer and Scott are conducting a mathematical investigation [1,2,16]. Danvy and his students, and Sheard and his students are conducting a more experimental investigation [17,18,21,22,35,36]. The present work continues our practical investigation.…”

The Second Futamura Projection for Type-Directed Partial Evaluation

“…These differences have contributed to the successful application of TDPE in various contexts, e.g., to perform semantics-based compilation [11]. An introductory account, as well as a survey of various treatments concerning NbE, can be found in Danvy's lecture notes [8].…”

“…The instantiation of height ge with these structures gives height . Applying the second Futamura projection as given in Equation 4 Figure 17: Instantiation via functors this purpose in several instances [5,6,10,11]. Having implemented the second Futamura projection, we can instead generate a compiler, which is the generating extension of an interpreter.…”

The second Futamura projection for type-directed partial evaluation

“…These differences have contributed to its successful application in various contexts, e.g., to perform semantics-based compilation [6]. TDPE is due to Danvy [1]; an introductory account, as well as a survey of various treatments concerning NbE, can be found in his lecture notes on TDPE [4].…”