Persistent Program Construction through Browsing and User Gesture with some Typing

Abstract

One method of evaluating programs is for them to be prepared as self contained pieces of source, then compiled, linked and executed. The last phase may involve binding to and manipulating persistent values. When the persistent store is supported by a user interface, the program construction can be augmented by the use of tokens as denotations for persistent values. That is, the manipulation of the persistent store by gesture, for example by an iconic interface linked to a mouse, can be used to provide tokens for persistent values. These tokens can be resolved to provide bindings at run-time, compile-time, program construction time or any mixture of these. In this paper the main styles of token resolution are described in terms of their influence on the persistent program evaluation. This is done in tandem with a description of an example user interface required to support these new styles of persistent programming. We note that other modern user interfaces, such as OpenLook and the Macintosh Programming Environment also allow the manipulation of files by user programs and by gesture. The difference here is that the technique is uniform and that the persistent store is strongly typed with a greater variety of types. Two prototype versions of these facilities have been implemented for the language Napier88.