A Universal Scripting Framework

The “little languages” approach to systems programming is flawed: inefficient, fragile, error-prone, inexpressive, and difficult to compose. A better solution is to embed task-specific sublanguages within a powerful, syntactically extensible, universal language, such as Scheme. I demonstrate two such embeddings that have been implemented in scsh, a Scheme programming environment for Unix systems programming. The first embedded language is a highlevel process-control notation; the second provides for Awk-like processing. Embedding systems in this way is a powerful technique: for example, although the embedded Awk system was implemented with 7% of the code required for the standard C-based Awk, it is significantly more expressive than its C counterpart.