Note that Parsing with derivatives is different than Matching regexes with derivatives.
Russ Cox likes regexes with derivatives -- they are a "win-win". He doesn't like parsing with derivatives because of the computational complexity. Linked from that article:
Your link doesn't really convince me they addressed the concerns ... There seems to be some hedging in the language, like that it seems to be efficient in practice; and that it should eventually be efficient in theory too.
Russ Cox likes regexes with derivatives -- they are a "win-win". He doesn't like parsing with derivatives because of the computational complexity. Linked from that article:
https://research.swtch.com/yaccalive
Your link doesn't really convince me they addressed the concerns ... There seems to be some hedging in the language, like that it seems to be efficient in practice; and that it should eventually be efficient in theory too.