Scratched my own itch while using Swift to replace various Ruby scripts due to performance annoyances (mainly startup) and lacking platform features (macOS APIs).

This tool transparently compiles your script, and caches the binary. I haven't tested on any other platform than macOS yet.

In an interactive terminal, it will only compile after running 3 times, to prevent compilation delays while developing. It uses extended attributes to keep track of the runcount, but maybe that's not the best solution (a small file could also work).