Sure, you are an experienced Haskeller so you have seen the sharp end of this. If this were a Haskell forum I might be proclaiming we have too many language ex

Sure, you are an experienced Haskeller so you have seen the sharp end of this. If this were a Haskell forum I might be proclaiming we have too many language extensions and the error messages are terrible! As were are on a forum for generalists I think the fairest thing to do is to point out as strongly as possible that, no, extensions don't mean that Haskellers have to choose to learn one of several incompatible languages, they don't mean you have to learn anything more than just another language feature, they're really not an impediment to being successful with Haskell in any way, and the fact that they are extensions at all is a quirk of having a language defined by a standard.