If you want to figure out how to write a lexer or parser, what better way than to read the code for one?

https://github.com/D-Programming-Language/dmd/blob/master/sr...

https://github.com/D-Programming-Language/dmd/blob/master/sr...

There's a lot of detail there, but the operation of both is straightforward.

I'd thought this subthread was discussing semantics.

For anyone who comes across this thread and is genuinely interested in educating themselves about how programming languages can be constructed in a principled way (what I would call sane) you can consult Pierce's Types and Programming Languages.

With some work anyone can learn the material. It's not as simple as reading a blog post unfortunately, but you'll have a much deeper understanding of what it means to build a programming language.

I'm in the midst of reading Types and Programming Languages right now.

I'm also reading the more recent Practical Foundations for Programming Languages by Robert Harper. It's written for a similar audience.

I would recommend both.