A Scheme for Little Languages in Interactive Graphics

Programming environments for interactive graphics software typically have a multiplicity of tools and applications. Many of these programs contain ad hoc ‘little language’ interpreters 1 that do many similar things in needlessly different ways. In particular, many little languages have, in addition to their special-purpose constructs, vestigial support for ordinary programming, such as variables, loops and conditionals. If a single, standard programming language were the basis for all these little languages, they could have complete, coherent programming semantics; they could communicate with each other more easily; no design work for basic constructs would be needed; and interpreter implementation work would be saved. The approach of reusing and extending the same core language and interpreter for a variety of little languages is the extension language approach. Scheme is proposed as a good choice for such a core language. Scheme is a simple, elegant, high-level programming language. Extendable implementations are readily available in C source form. Example applications in Scheme from interactive graphics are presented that would be nearly impossible to code in a typical scripting language and very tedious to code in a lower-level implementation language such as C.