I had been wondering how one was meant to provide meaningful error messages for code that failed to parse or failed to lex using the LR approach and looks like maybe the answer is "with difficulty", which is definitely a downer.
Phillipe Charles Phd thesis[0] describes a method for generating good error messages with an LALR parser generator. lpg[1] implements these techniques.
I had been wondering how one was meant to provide meaningful error messages for code that failed to parse or failed to lex using the LR approach and looks like maybe the answer is "with difficulty", which is definitely a downer.