-- | Internal utilities. module Safe.Util where import Data.Maybe (.^) :: (b -> c) -> (a1 -> a2 -> b) -> a1 -> a2 -> c (.^) f g x1 x2 = f (g x1 x2) (.^^) :: (b -> c) -> (a1 -> a2 -> a3 -> b) -> a1 -> a2 -> a3 -> c (.^^) f g x1 x2 x3 = f (g x1 x2 x3) liftMay :: (a -> Bool) -> (a -> b) -> (a -> Maybe b) liftMay test func val = if test val then Nothing else Just $ func val fromNoteModule :: String -> String -> String -> Maybe a -> a fromNoteModule modu note func = fromMaybe (error msg) where msg = modu ++ "." ++ func ++ (if null note then "" else ", " ++ note) fromNoteEitherModule :: String -> String -> String -> Either String a -> a fromNoteEitherModule modu note func = either (error . msg) id where msg ex = modu ++ "." ++ func ++ " " ++ ex ++ (if null note then "" else ", " ++ note) eitherToMaybe :: Either a b -> Maybe b eitherToMaybe = either (const Nothing) Just