People should note that this isn't usually how we construct compilers in industry today.

(This comment is posted every time but it's true.)

It really wasn't how compilers were constructed in '96 either. I was very into compilers in the late 80's and even then we didn't handwrite lexers or parsers. I was using bison and flex around '89.

Basically no serious programming language uses bison or flex, and everything that does (awk is YACC based) has terrible error messages. People totally do handwrite lexers and parsers, if you use some language in earnest the chances it has a handwritten parser or lexer or both are far greater than that it has been developed with bison/flex.

> Basically no serious programming language uses bison or flex,

https://en.wikipedia.org/wiki/GNU_Bison#Use: Ruby, PHP, GCC until 2004, Go, Bash, PostgreSQL, MySQL, Perl.

Can we stop with this "duh, real programmers write their own handwritten parsers"? Parser generators are awesome! They force you to write a declarative grammar which a human can understand. If you're designing a language this is very useful. With a handwritten parser you're very likely to encode some unintended behaviour in edge cases; using a parser generator early in this process will very quickly reveal the ambiguities.

That doesn't mean that parser generators are always the best. There are many use cases where a handwritten parser is better. But the picture is way more nuanced than "no serious programming language uses bison or flex".

I'm guilty of being overly hyperbolic, and you are right to correct me. But if your poster boys to illustrate the benefits of parser generators forcing you to write a declarative grammar which a human can understand are perl, bash or even postgresql, I'm not sure what to say ;)

Apart from Go, (and maybe PHP, which I don't know well enough to judge) all the languages you list have pretty horrible syntax that probably few (ruby?) to basically none of its users (bash, perl, C++, postgresql) really understand.

https://github.com/ruby/ruby/blob/master/parse.y

https://whitequark.org/blog/2013/04/01/ruby-hacking-guide-ch...

It also changes syntax in patch level versions: https://github.com/whitequark/parser.