@@ -44,7 +44,6 @@ module Data.Aeson.Types.Internal
4444 , parse
4545 , parseEither
4646 , parseMaybe
47− , parseFail
4847 , modifyFailure
4948 , prependFailure
5049 , parserThrowError
@@ -343,10 +342,6 @@ instance Monoid (Parser a) where
343342 mappend = (<>)
344343 {-# INLINE mappend #-}
345344
346−-- | Raise a parsing failure with some custom message.
347−parseFail :: String -> Parser a
348−parseFail = fail
349−
350345apP :: Parser (a -> b) -> Parser a -> Parser b
351346apP d e = do
352347 b <- d
@@ -586,53 +581,41 @@ data Options = Options
586581 -- the constructor tag. If 'False' the encoding will always
587582 -- follow the `sumEncoding`.
588583 , omitNothingFields :: Bool
589− -- ^ If 'True', record fields with a 'Nothing' value will be
590− -- omitted from the resulting object. If 'False', the resulting
584+ -- ^ If 'True' record fields with a 'Nothing' value will be
585+ -- omitted from the resulting object. If 'False' the resulting
591586 -- object will include those fields mapping to @null@.
592587 --
593− -- Note that this /does not/ affect parsing: 'Maybe' fields are
594− -- optional regardless of the value of 'omitNothingFields', subject
595− -- to the note below.
596− --
597588 -- === Note
598589 --
599590 -- Setting 'omitNothingFields' to 'True' only affects fields which are of
600− -- type 'Maybe' /uniformly/ in the 'ToJSON' instance.
601− -- In particular, if the type of a field is declared as a type variable, it
591+ -- type 'Maybe' /uniformly/ in the 'ToJSON' or 'FromJSON' instance. In
592+ -- particular, if the type of a field is declared as a type variable, it
602593 -- will not be omitted from the JSON object, unless the field is
603594 -- specialized upfront in the instance.
604595 --
605− -- The same holds for 'Maybe' fields being optional in the 'FromJSON' instance.
606− --
607596 -- ==== __Example__
608597 --
609598 -- The generic instance for the following type @Fruit@ depends on whether
610599 -- the instance head is @Fruit a@ or @Fruit (Maybe a)@.
611600 --
612601 -- @
613− -- data Fruit a = Fruit
602+ -- data Fruit a =
614603 -- { apples :: a -- A field whose type is a type variable.
615604 -- , oranges :: 'Maybe' Int
616− -- } deriving 'Generic'
605+ -- }
606+ --
607+ -- options :: 'Options'
608+ -- options = 'defaultOptions' { 'omitNothingFields' = 'True' }
617609 --
618610 -- -- apples required, oranges optional
619611 -- -- Even if 'Data.Aeson.fromJSON' is then specialized to (Fruit ('Maybe' a)).
620− -- instance 'Data.Aeson.FromJSON' a => 'Data.Aeson.FromJSON' (Fruit a)
612+ -- instance 'Data.Aeson.FromJSON' a => 'Data.Aeson.FromJSON' (Fruit a) where
613+ -- 'Data.Aeson.fromJSON' = 'Data.Aeson.genericFromJSON' options
621614 --
622615 -- -- apples optional, oranges optional
623616 -- -- In this instance, the field apples is uniformly of type ('Maybe' a).
624− -- instance 'Data.Aeson.FromJSON' a => 'Data.Aeson.FromJSON' (Fruit ('Maybe' a))
625− --
626− -- options :: 'Options'
627− -- options = 'defaultOptions' { 'omitNothingFields' = 'True' }
628− --
629− -- -- apples always present in the output, oranges is omitted if 'Nothing'
630− -- instance 'Data.Aeson.ToJSON' a => 'Data.Aeson.ToJSON' (Fruit a) where
631− -- 'Data.Aeson.toJSON' = 'Data.Aeson.genericToJSON' options
632− --
633− -- -- both apples and oranges are omitted if 'Nothing'
634− -- instance 'Data.Aeson.ToJSON' a => 'Data.Aeson.ToJSON' (Fruit ('Maybe' a)) where
635− -- 'Data.Aeson.toJSON' = 'Data.Aeson.genericToJSON' options
617+ -- instance 'Data.Aeson.FromJSON' a => 'Data.Aeson.FromJSON' (Fruit ('Maybe' a)) where
618+ -- 'Data.Aeson.fromJSON' = 'Data.Aeson.genericFromJSON' options
636619 -- @
637620 , sumEncoding :: SumEncoding
638621 -- ^ Specifies how to encode constructors of a sum datatype.