What does this add to inotifywait? That does exactly the same as this project, which uses inotifywait to reimplement inotifywait.
For example:
dnf install inotify-tools
or
apt-get install inotify-tools
ifnotifywait doesn't exist on macOS, so in addition to that not being an option on macos, this would be something you could write tools that a team who used multiple platforms, or a person with setups on multiple os's, could use. I suspect this might even be usable on windows.
[edit: fswatch looks very promising, and may be a better choice than either ifnotifywait or watchman]
Discovered fswatch recently, it's proved very useful, my favorite use being replacing a few situations where I was using sshfs with fswatch+rsync: no network lag on save/load, can even work offline, but everything still makes its way to the network destination!