Almost everyone who works on the D compiler has come to it as a hobby. The books don't teach you how to write a good compiler i.e. most textbooks spend years on

Almost everyone who works on the D compiler has come to it as a hobby. The books don't teach you how to write a good compiler i.e. most textbooks spend years on parsing theory when 99% of real compilers use handwritten parsers which can basically be made up on the fly.