> if you have a function, in production use, of type (X -> Maybe Y), you can't "weaken your assumptions for the input and strengthen your promises for the output" (which would be an improvement) and rewrite it to the type (Maybe X -> Y).
If your value of Y is predicated on receiving an X, I have trouble seeing how you would write such a function. If you have a default value, then Haskell would solve it just like any language with optionals:
y :: Int -> String
(fromMaybe "defaultValue" (map y (Just 3))
> Several other null-safe languages [...] returning Y implies returning Y or Null.
I have trouble seeing how the language is null-safe in that situation.
If your value of Y is predicated on receiving an X, I have trouble seeing how you would write such a function. If you have a default value, then Haskell would solve it just like any language with optionals:
> Several other null-safe languages [...] returning Y implies returning Y or Null.I have trouble seeing how the language is null-safe in that situation.