[JonChesterfield]

There are lots of different regex implementations. The readme mentions sed behaving differently on different platforms. The readme doesn't say what regex language this tool implements. There doesn't seem to be any tests. Thus I don't know what this tool actually does.

[catatsuy]

Thank you for your feedback. The current implementation of purl uses Go's regexp package for regex operations, which ensures consistent behavior across platforms. I acknowledge the README does not specify this yet, and I plan to update it to clarify the regex implementation used.