On Mon, 17 Aug 2020 at 07:10, Anthony Clayden
Hi Tom, I see nothing bizarre nor counterintuitive. Perhaps you need to retrain your intuitions ;-)
I have just noticed that with ScopedTypeVariables one can write the following bizarre definition
-- Inferred signature: -- add :: Num a => a -> a -> a add (x :: a) (y :: b) = x + y
What do you think is bizarre? GHC makes a reasonable attempt to use the tyvar names you put in a signature -- remembering that alpha-renaming means the name is not really significant. I can get `add :: Num c => c -> c -> c`, etc.
I can't speak for Tom, but to me the above feels very similar to writing something like: add :: _ => a -> b -> _ add x y = x + y But that doesn't type check, since the types `a` and `b` are not the same, but `+` needs them to be. Erik