I'm a huge fan of visual-regexp-replace. I've written crazy regexps that would be impossible without its feedback.
miniblog.
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Compelling demonstration of parser combinators for date parsing: https://medium.com/mercury-bank/a-magic-date-input-using-parser-combinators-in-typescript-3c779741bf4c
You build up a series of functions for parsing elements, which composes much more nicely than regexps.
Interesting discussion on globs vs regexps for package configuration: https://github.com/facebook/jest/issues/7185
Is it true that all globs can be expressed as regexps? I can imagine there might be some cute tricks that can't be converted.
(I definitely find globs easier to read though!)
Comb is an Emacs tool for exploring projects with regexps: https://github.com/cyrus-and/comb/blob/master/README.md
The UI looks very polished!