A professor in gradschool insisted on us writing hand-written parsers to better understand associativity, operant ordering and so on and identify useful pattern

A professor in gradschool insisted on us writing hand-written parsers to better understand associativity, operant ordering and so on and identify useful patterns, then implementing ASTs and interpreters directly ontop of the parsers. It was a tough class, but to be honest it was one of the most fun ones as well. In undergrad, I asked the professor assigned the compilers class whether he would offer it during fall, but he said that unless he managed to completely revamp the class into more real-world and practical stuff like using LLVM backend instead of wasting time on parsers like in the dragon book and the tiger book, he wouldnt offer it.