Types are typically better documentation than comments: addCD :: CDCollection -> String -> Maybe String -> NonNegativeInt -> NonNegativeDouble -> Either Fa

Types are typically better documentation than comments: addCD :: CDCollection -> String -> Maybe String -> NonNegativeInt -> NonNegativeDouble -> Either FailureType CDCollection This answers all your questions except for "Which related methods are available?" and the anwsers are checked for correctness at compile time!