Oh, I was talking much more about how you can first learn how to write a compiler. I wasn't talking about how you write a production industry-strength compiler.

Btw, I mentioned parser combinators: those are basically just a front-end. Similar to regular expressions. The implementation can be all kinds of things, eg could be recursive descent or a table or backtracking or whatever. (Even finite automata, if your combinators are suitably restricted.)

The thing about LR parsers is that since it is parsing bottom-up, you have no idea what larger syntactic structure is being built, so error recovery is ugly, and giving the user a sensible error message is a fool’s errand.

In the end, all the hard work in a compiler is in the back-end optimization phases. Put your mental energy there.

Some people appreciate that an LR/LALR parser generator can prove non-ambiguity and linear time parse-ability of a grammar. A couple of examples are the creator of the Oil shell, and one of the guys responsible for Rust.

It does make me wonder though about why grammars have to be so complicated that such high-powered tools are needed. Isn't the gist of LR/LALR that the states of an automaton that can parse CFGs can be serialised to strings, and the set of those strings forms a regular language? Once you have that, many desirable "infinitary" properties of a parsing automaton can be automatically checked in finite time. LR and LALR fall out of this, in some way.