I'm doing research in PL, but as much as I like it I just don't think that designing your own PL is much of a benefit.

I think if more people tried to write their own language, there would be far fewer flame wars about inane things like syntax, and far fewer poorly argued debates about types.

I'd much rather people just leaf through some the PL research that already exists rather than try and invent their own. Most people don't even know what HM is.

Plus, learning about parsing is definitely practical and useful.

I completely disagree. Writing a parser is a character-building exercise. It ultimately wastes more time than its worth and you're better off using someone else's parsing system anyway.

Actually I think we basically agree, it's just a matter of degree. When I read "write your own language" I'm mostly thinking of the kinds of work you might do in an undergrad PL class, which I think works well as a kind of antidote to the Java monoculture. I agree that inventing and designing a custom language with no reference, in a vacuum, would probably not be helpful.

As for parsing, that was almost exactly my point, learning about parsing, and realizing what kind of work is involved, is just the experience you need to reject being assigned the writing of a custom XML parser by a clueless manager (true story).