Is it a must for every programmer to learn regular expressions?

But it's also a must that you realize that despite the fact that they're exceptionally useful and widely supported, regexes are a disgusting abomination, one that we should be absolutely mortified to be associated with. It's one of the worst syntaxes to ever be invented, and every one of us should feel the cold stink of UX failure wash over us every time we write a regex. If we ever catch ourselves writing a DSL that in any way, shape, or form resembles regular expressions, we should stop immediately and ask what the fuck is wrong with us and why we're being so opaque and random. Regular expressions are quite literally one of the worst syntaxes to ever be introduced in our field.

I worry a lot when someone doesn't know regular expressions at all. But I worry far more when someone thinks they're beautiful. That person has far too high a tolerance for unintuitive syntax and code, and will cause vastly more damage to my codebase than even the rank amateur that still uses "goto" on a regular basis.

Which is not to say that we shouldn't lean on regexes heavily anyways when they're appropriate - as programmers our primary job description is that we're paid good money to work with shitty interfaces in order to express simple ideas and algorithms.

Anything that comes out of the whole chomskian hierarchy stuff isn't going to look intuitive. But the point is that it is a particular, very rigorously defined system of representation. And various systems of representation are always more or less intuitively accessible - and come with a whole set of trade offs around what they can represent vs their ease of use etc...

These things just are - written into the laws of the world. They are discovered - not invented. We pick them up and use them as we would rocks left lying around. We find better ones when we can and fashion better ones when we can too...