Hi, Ruud Koot wrote:
1) Consider the higher-order function 'map'. With tracked exceptions you would probably want to give it a type such as:
map :: forall a b e. (a -> b throws e) -> [a] -> [b] throws e
To account for exceptions hidden in thunks, I would have expected something more like this: map :: forall a b e1 e2 e3 e4 . (forall e . a throws e -> b throws e1 e) throws e2 -> [a throws e3] throws e4 -> [b throws (e1 e3, e2)] throws e4 map f [] = [] map f (x :: xs) = f x :: map f xs Note that e1 is of kind "exception -> exception". If it is a constant function, f does not force its argument; if it is the identity function, f forces its argument but cannot throw any other exceptions; etc. Interestingly, exception tracking seems to feel like strictness analysis. Tillmann