youngSort :: [Person] -> [Person]
youngSort list = case (list) of
[] -> []
((Person (a, b, c, age)):xs) -> youngSort [(Person (a, b, c, younger)) | (Person (a, b, c, younger)) <- xs, younger <= age]
++ [(Person (a, b, c, age))] ++ youngSort [(Person (a, b, c, older)) | (Person (a, b, c, older)) <- xs, older > age]