Ultimately, the reason many languages use manually written parsers is because the code generated by parser generators just isn't worth the time savings not manu

Ultimately, the reason many languages use manually written parsers is because the code generated by parser generators just isn't worth the time savings not manually writing a parser instead. The underlying assumption is that that is somehow super hard, error prone, and time consuming. I think that assumption is simply wrong. I had my compiler course at the University of Utrecht in the mid nineties. The local faculty there had some functional programming pioneers and did a lot of work on parse generators. So, I learned how to write a parser generator in Gopher (a Haskell predecessor). Very nice course and definitely a bit of a mind fuck since I also had to wrap my head around monads at the same time. And of course not really that useful for real world stuff and I've since forgotten most of what I learned as I have not used it in over 25 years. A few years ago, I had to sit down and write a parser for a little query language that we came up with. I spend some time looking at all sorts of convoluted tools for this and refreshing some decades old knowledge on grammars to actually try to understand what the tools were trying to do. I then found a useful example of a lexer that simply used regular expressions and suddenly realized I was wasting time and that this stuff was stupidly simple. I then knocked out this little project out in a few hours using that. Once you have a lexer, things get easy and they are not that hard to write. I think this is why people end up doing these things manually. It's just not that hard or worth automating and it's rare enough that it's not worth investing time in learning new tools. Also, modern languages are a lot better at this stuff too. String handling in C was always a bit tedious. But modern languages come with so many built in stuff for that that it's not really a burden. So, in short, parser generators solve a problem that's not really that big of a problem anymore.