Rash: From Reckless Interactions to Reliable Programs William Gallard Hatch Matthew Flatt University of Utah University of Utah USA USA
[email protected] [email protected] Abstract them along a spectrum of program maturity and scale. Mov- Command languages like the Bourne Shell provide a terse ing code along this scale is often viewed as a transition from syntax for exploratory programming and system interaction. “scripts” to more mature “programs,” and current research Shell users can begin to write programs that automate their aims to improve that transition, especially through grad- tasks by simply copying their interactions verbatim into a ual typing [18, 20]. In this paper, we address a point in the script file. However, command languages usually scale poorly spectrum that precedes even the “script” level of maturity: beyond small scripts, and they can be difficult to integrate command sequences in an interactive shell. into larger programs. General-purpose languages scale well, Different features and aspects of programming languages but are verbose and unwieldy for common interactive actions are well suited to different stages of program maturity. For such as process composition. example, static types are clearly useful for ensuring and We present Rash, a domain-specific command language maintaining software correctness, but types are often seen embedded in Racket. Rash provides a terse and extensible as burdensome or obstructive when writing scripts, so many syntax for interactive system administration and scripting, scripting languages eschew types. Programmers want brevity as well as easy composition of both Racket functions and and even less formality in interactive settings, so read-eval- operating system processes.