webcom.com In the fall of 1990, one of us (Rakitzis) re-implemented the Plan 9 command interpreter, rc, for use as a UNIX shell. Experience with that shell led us to wonder whether a more general approach to the design of shells was possible, and this paper describes the result of that experimentation. We applied concepts from modern functional programming languages, such as Scheme and ML, to shells, which typically are more concerned with UNIX features than language design. Our shell is both simple and highly programmable. By exposing many of the internals and adopting constructs from functional programming languages, we have created a shell which supports new paradigms for programmers.