fun :: a -> b

fun :: a -> f b -> g c d

fun :: Class a => a -> b -> c

fun :: (Class a, Class b) => a -> b -> c

fun :: a
    -> b
    -> c

fun :: a
 -> b
 -> c

fun :: a
 -> b
   -> c

fun :: a -> b -- ^ Hello
   -> c

fun :: a -> b
   -> c -- ^ Hello

fun :: (Class a, Class b) => a -> b
   -> c -- ^ Hello

fun :: (Class a, Class b) =>
 a -> b
   -> c -- ^ Hello