A Programming Environment is a system that provides computer assistance during software development and maintenance. The primary objective of this work concerns practically usable methods and tools in the construction of incremental and integrated programming environments that provide good support for debugging and testing of programs in a distributed context, in our case a host-target configuration. Such a system, called DICE-Distributed Incremental Compiling Environment, has been constructed and currently supports development of PASCAL programs. Three of the papers in this volume are concerned with this topic.

It is demonstrated how powerful symbolic debuggers may be implemented with the aid of an incremental compiler. Methods for statement-level incremental compilation are described. Strategies suitable for implementing programming environments are discussed and exemplified by the DICE system. Some preliminary experience from the use of the prototype version of the DICE system is given. The concept of Consistent Incremental Compilation is defined, both informally and by algebraic methods. A semi-form al description of the architecture of the DICE system is presented. Many aspects of this system description are relevant for a large class of programming environments of this kind. Problems that arise from allowing mixed execution and program editing are also considered.

One of the tools in a programming environment is the prettyprinter. The topic of the fourth paper is the automatic generation of prettyprinters. A language-independent algorithm for adaptive prettyprinting is described together with its application to ADA and PASCAL. Problems associated with the representation and prettyprinting of comments in abstract syntax trees are discussed together with some solutions.