[seanmcdirmid]

Scala and C# are by hand. I imagine C++ is also since there is no other way to do it. Java uses JavaCC, Lua is by hand

Using tools is often more complicated than just writing code, it isn't that hard to write a recursive descent parser, and you have the flexibility if loading it with all the error recovery you want. What tools give you is potentially better parser performance and more theoretic assurances (useful for tricky grammars).

[platz]

After the comments I've seen from paulp, I'd hardly believe that way Scala did this was optimal, although I'm not sure there were any issues with lexing & parsing

[seanmcdirmid]

It's not optimal and it doesn't matter considering parsing overhead is just noise compared to type system computations.