Porting Scheme Programs

standard and the Scheme reports define not one but an entire family of programming languages. Programmers can still create useful programs in small dialect-specific extensions of the standardized Scheme language but porting such programs from one dialect to another requires tedious work. This paper presents scmxlate, a lightweight software tool that automates a large portion of this work. 1. ON THE PORTABILITY OF SCHEME The existence of the IEEE Scheme Standard [6] appears to suggest that Scheme programmers can write a program once and run it everywhere. Unfortunately, appearances are deceiving. The Scheme standard and the Scheme reports [16, 15, 1, 2, 8] do not define a useful programming language for all platforms. Instead they—like the Algol 60 [9] report— define a family of programming languages that individua

Models of Control and Their Implications for Programming Language Design

This work uses denotational models to understand and improve the part of a programming language concerned with non-local control operators. These operators let the programmer identify and restore arbitrary control contexts in the program execution path, and thus form a powerful component of many modern programming languages. We use a variety of denotational models to tackle the issues of (1) describing a control language mathematically, and (2) using the model's apparatus to obtain information useful for designing the language. For this, the full abstraction criterion of testing a model against a language is viewed as a feedback loop that suggests language changes. The results from radically different models, for a variety of control manipulation languages, uniformly emphasize the need for delimiting control actions. In the case of higher-order control, this takes the form of a systematic handling of control objects. To check the pragmatics of the new control techniques, we present an ..

Reasoning with Continuations II: Full Abstraction for Models of Control

A fully abstract model of a programming language assigns the same meaning to two terms if and only if they have the same operational behavior. Such models are well-known for functional languages but little is known about extended functional languages with sophisticated control structures. We show that a direct model with error values and the conventional continuation model are adequate for functional languages augmented with first- and higher-order control facilities, respectively. Furthermore, both models become fully abstract on adding a control delimiter and a parallel conditional to the programming languages