Regardless of whether or not your code has pre-processing steps,
post-processing steps, or both, it's best to use fast tools that
other tools can easily consume via stdout
.
An asset pipeline for CSS can be constructed entirely this way.
It's useful to have a tool that can watch for changes on one or more files and execute commands (e.g. one-or-more compilation steps) when there are changes.
catw
is one such tool.