[ie]

This looks incredibly useful and I appreciate the focus on performance. I often avoid writing helpers for type checking edge cases due to performance concerns, but you've done the hard work for me. Thank you.

[lucono]

Thanks. I developed and used it as a utility in a bigger library that worked heavily with types, but later exported it to its own project so I could share it, after I realized how useful it was, even stand-alone.

It is very highly optimized, as performance was of critical importance.