With Racket's path utilities I was able to get this script working a lot faster than I was able to get an earlier Guile script working. (fn:1) Why are command-line arguments treated as vectors? That's a mystery for later. In the meantime this script is useful, and it is the first step toward getting all my teaching materials generated through Racket scripts. DrRacket on windows may provide a way to ease teachers towards independence with free software. Once people can do everything with free applications, like DrRacket, Gimp, Firefox, and Inkscape: they won't feel dependent on a proprietary OS.

Maybe it's just because of all the hours spent with the Racket Language since I made the Guile Scheme script, but Racket seemed to let me develop a batch conversion script much faster. Previous experience with `build-path` helped a lot, I never saw anything similar in the Guile documentation so a lot of time went into developing string-based utilities to manipulat paths. I imagine this Racket version could work in DrRacket on a Windows OS, if ImageMagick's `convert` and the `potrace` utility are installed.