It's sort of amazing that you're replying to a post suggesting something I suggested, by re-suggesting what all 3 posts prior to you suggested. But as I've sai

It's sort of amazing that you're replying to a post suggesting something I suggested, by re-suggesting what all 3 posts prior to you suggested. But as I've said, yeah you can do this. But it's unfortunate because it destroys a lot of information that's useful in the type signature. Haskell does this with exception hierarchies and some clever runtime casting attempts, but even that has ergonomic issues. What'd be really amazing is if we could get the totality checking of pattern matching but also the composability of exception handlers, and that's what the next generation of error handling primitives are trying to do.