Watch_haml is a project mainly written in PYTHON and SHELL, it's free.
Watches haml files and converts them to html if changed.
Usage: ./watch_haml.py
Watches current directory and, if filename.haml is modified, runs
haml filename.haml filename.html
Based on autocompile.py example from https://github.com/seb-m/pyinotify/
Requires pyinotify.