@@ -5,16 +5,19 @@
55{-# LANGUAGE FlexibleInstances #-}
66{-# LANGUAGE GADTs #-}
77{-# LANGUAGE MultiParamTypeClasses #-}
8−{-# LANGUAGE NoImplicitPrelude #-}
8+{-# LANGUAGE NamedFieldPuns #-}
99{-# LANGUAGE OverloadedStrings #-}
10−{-# LANGUAGE PolyKinds #-}
1110{-# LANGUAGE RecordWildCards #-}
1211{-# LANGUAGE ScopedTypeVariables #-}
1312{-# LANGUAGE TypeOperators #-}
14−{-# LANGUAGE TupleSections #-}
13+{-# LANGUAGE TypeSynonymInstances #-}
1514{-# LANGUAGE UndecidableInstances #-}
1615{-# LANGUAGE ViewPatterns #-}
1716
17+#if __GLASGOW_HASKELL__ >= 706
18+{-# LANGUAGE PolyKinds #-}
19+#endif
20+
1821#include "incoherent-compat.h"
1922#include "overlapping-compat.h"
2023
@@ -42,9 +45,6 @@ module Data.Aeson.Types.FromJSON
4245 , coerceFromJSONKeyFunction
4346 , mapFromJSONKeyFunction
4447
45− , GFromJSONKey()
46− , genericFromJSONKey
47−
4848 -- * List functions
4949 , listParser
5050
@@ -52,42 +52,34 @@ module Data.Aeson.Types.FromJSON
5252 , withObject
5353 , withText
5454 , withArray
55+ , withNumber
5556 , withScientific
5657 , withBool
57− , withEmbeddedJSON
5858
5959 -- * Functions
6060 , fromJSON
6161 , ifromJSON
62− , typeMismatch
63− , unexpected
64− , parseField
65− , parseFieldMaybe
66− , parseFieldMaybe'
67− , explicitParseField
68− , explicitParseFieldMaybe
69− , explicitParseFieldMaybe'
70− , parseIndexedJSON
71− -- ** Operators
7262 , (.:)
7363 , (.:?)
7464 , (.:!)
7565 , (.!=)
66+ , typeMismatch
7667
7768 -- * Internal
7869 , parseOptionalFieldWith
7970 ) where
8071
72+import Prelude ()
8173import Prelude.Compat
8274
83−import Control.Applicative ((<|>), Const(..), liftA2)
84−import Control.Monad (zipWithM)
75+import Control.Applicative ((<|>), Const(..))
76+import Control.Monad ((<=<), zipWithM)
8577import Data.Aeson.Internal.Functions (mapKey)
86−import Data.Aeson.Parser.Internal (eitherDecodeWith, jsonEOF)
8778import Data.Aeson.Types.Generic
8879import Data.Aeson.Types.Internal
80+import Data.Attoparsec.Number (Number(..))
8981import Data.Bits (unsafeShiftR)
90−import Data.Fixed (Fixed, HasResolution (resolution), Nano)
82+import Data.Fixed (Fixed, HasResolution)
9183import Data.Functor.Compose (Compose(..))
9284import Data.Functor.Identity (Identity(..))
9385import Data.Functor.Product (Product(..))
@@ -96,31 +88,26 @@ import Data.Hashable (Hashable(..))
9688import Data.Int (Int16, Int32, Int64, Int8)
9789import Data.List.NonEmpty (NonEmpty(..))
9890import Data.Maybe (fromMaybe)
99−import Data.Semigroup ((<>))
91+import Data.Monoid ((<>))
10092import Data.Proxy (Proxy(..))
10193import Data.Ratio ((%), Ratio)
102−import Data.Scientific (Scientific, base10Exponent)
94+import Data.Scientific (Scientific)
10395import Data.Tagged (Tagged(..))
10496import Data.Text (Text, pack, unpack)
105−import Data.Time (Day, DiffTime, LocalTime, NominalDiffTime, TimeOfDay, UTCTime, ZonedTime)
106−import Data.Time.Calendar.Compat (CalendarDiffDays (..), DayOfWeek (..))
107−import Data.Time.LocalTime.Compat (CalendarDiffTime (..))
108−import Data.Time.Clock.System.Compat (SystemTime (..))
109−import Data.Time.Format.Compat (parseTimeM, defaultTimeLocale)
97+import Data.Time (Day, LocalTime, NominalDiffTime, TimeOfDay, UTCTime, ZonedTime)
98+import Data.Time.Format (parseTime)
99+import Data.Time.Locale.Compat (defaultTimeLocale)
110100import Data.Traversable as Tr (sequence)
111101import Data.Vector (Vector)
112102import Data.Version (Version, parseVersion)
113−import Data.Void (Void)
114103import Data.Word (Word16, Word32, Word64, Word8)
115104import Foreign.Storable (Storable)
116−import Foreign.C.Types (CTime (..))
117105import GHC.Generics
118106import Numeric.Natural (Natural)
119107import Text.ParserCombinators.ReadP (readP_to_S)
120108import Unsafe.Coerce (unsafeCoerce)
121109import qualified Data.Aeson.Parser.Time as Time
122110import qualified Data.Attoparsec.ByteString.Char8 as A (endOfInput, parseOnly, scientific)
123−import qualified Data.ByteString.Lazy as L
124111import qualified Data.DList as DList
125112import qualified Data.HashMap.Strict as H
126113import qualified Data.HashSet as HashSet
@@ -136,27 +123,24 @@ import qualified Data.Text as T
136123import qualified Data.Text.Encoding as T
137124import qualified Data.Text.Lazy as LT
138125import qualified Data.Tree as Tree
139−import qualified Data.UUID.Types as UUID
140126import qualified Data.Vector as V
141127import qualified Data.Vector.Generic as VG
142128import qualified Data.Vector.Primitive as VP
143129import qualified Data.Vector.Storable as VS
144130import qualified Data.Vector.Unboxed as VU
145131
146−import qualified GHC.Exts as Exts
147−import qualified Data.Primitive.Array as PM
148−import qualified Data.Primitive.SmallArray as PM
149−import qualified Data.Primitive.Types as PM
150−
151−#if MIN_VERSION_primitive(0,6,4)
152−#if !MIN_VERSION_primitive(0,7,0)
153−import qualified Data.Primitive.UnliftedArray as PM
154−#endif
155−import qualified Data.Primitive.PrimArray as PM
132+#ifndef HAS_COERCIBLE
133+#define HAS_COERCIBLE (__GLASGOW_HASKELL__ >= 707)
156134#endif
157135
158−
136+#if HAS_COERCIBLE
159137import Data.Coerce (Coercible, coerce)
138+coerce' :: Coercible a b => a -> b
139+coerce' = coerce
140+#else
141+coerce' :: a -> b
142+coerce' = unsafeCoerce
143+#endif
160144
161145parseIndexedJSON :: (Value -> Parser a) -> Int -> Value -> Parser a
162146parseIndexedJSON p idx value = p value <?> Index idx
@@ -165,7 +149,7 @@ parseIndexedJSON p idx value = p value <?> Index idx
165149parseIndexedJSONPair :: (Value -> Parser a) -> (Value -> Parser b) -> Int -> Value -> Parser (a, b)
166150parseIndexedJSONPair keyParser valParser idx value = p value <?> Index idx
167151 where
168− p = withArray "(k, v)" $ \ab ->
152+ p = withArray "(k,v)" $ \ab ->
169153 let n = V.length ab
170154 in if n == 2
171155 then (,) <$> parseJSONElemAtIndex keyParser 0 ab
@@ -177,34 +161,43 @@ parseIndexedJSONPair keyParser valParser idx value = p value <?> Index idx
177161parseJSONElemAtIndex :: (Value -> Parser a) -> Int -> V.Vector Value -> Parser a
178162parseJSONElemAtIndex p idx ary = p (V.unsafeIndex ary idx) <?> Index idx
179163
164+scientificToNumber :: Scientific -> Number
165+scientificToNumber s
166+ | e < 0 = D $ Scientific.toRealFloat s
167+ | otherwise = I $ c * 10 ^ e
168+ where
169+ e = Scientific.base10Exponent s
170+ c = Scientific.coefficient s
171+{-# INLINE scientificToNumber #-}
172+
180173parseRealFloat :: RealFloat a => String -> Value -> Parser a
181−parseRealFloat _ (Number s) = pure $ Scientific.toRealFloat s
182−parseRealFloat _ Null = pure (0/0)
183−parseRealFloat name v = prependContext name (unexpected v)
174+parseRealFloat _ (Number s) = pure $ Scientific.toRealFloat s
175+parseRealFloat _ Null = pure (0/0)
176+parseRealFloat expected v = typeMismatch expected v
184177{-# INLINE parseRealFloat #-}
185178
186−parseIntegralFromScientific :: forall a. Integral a => Scientific -> Parser a
187−parseIntegralFromScientific s =
179+parseIntegralFromScientific :: forall a. Integral a => String -> Scientific -> Parser a
180+parseIntegralFromScientific expected s =
188181 case Scientific.floatingOrInteger s :: Either Double a of
189182 Right x -> pure x
190− Left _ -> fail $ "unexpected floating number " ++ show s
183+ Left _ -> fail $ "Floating number specified for " ++ expected ++ ": " ++ show s
191184{-# INLINE parseIntegralFromScientific #-}
192185
193186parseIntegral :: Integral a => String -> Value -> Parser a
194−parseIntegral name =
195− prependContext name . withBoundedScientific' parseIntegralFromScientific
187+parseIntegral expected =
188+ withScientific expected $ parseIntegralFromScientific expected
196189{-# INLINE parseIntegral #-}
197190
198−parseBoundedIntegralFromScientific :: (Bounded a, Integral a) => Scientific -> Parser a
199−parseBoundedIntegralFromScientific s = maybe
200− (fail $ "value is either floating or will cause over or underflow " ++ show s)
191+parseBoundedIntegralFromScientific :: (Bounded a, Integral a) => String -> Scientific -> Parser a
192+parseBoundedIntegralFromScientific expected s = maybe
193+ (fail $ expected ++ " is either floating or will cause over or underflow: " ++ show s)
201194 pure
202195 (Scientific.toBoundedInteger s)
203196{-# INLINE parseBoundedIntegralFromScientific #-}
204197
205198parseBoundedIntegral :: (Bounded a, Integral a) => String -> Value -> Parser a
206−parseBoundedIntegral name =
207− prependContext name . withScientific' parseBoundedIntegralFromScientific
199+parseBoundedIntegral expected =
200+ withScientific expected $ parseBoundedIntegralFromScientific expected
208201{-# INLINE parseBoundedIntegral #-}
209202
210203parseScientificText :: Text -> Parser Scientific
@@ -214,20 +207,13 @@ parseScientificText
214207 . T.encodeUtf8
215208
216209parseIntegralText :: Integral a => String -> Text -> Parser a
217−parseIntegralText name t =
218− prependContext name $
219− parseScientificText t
220− >>= rejectLargeExponent
221− >>= parseIntegralFromScientific
222− where
223− rejectLargeExponent :: Scientific -> Parser Scientific
224− rejectLargeExponent s = withBoundedScientific' pure (Number s)
210+parseIntegralText expected t =
211+ parseScientificText t >>= parseIntegralFromScientific expected
225212{-# INLINE parseIntegralText #-}
226213
227214parseBoundedIntegralText :: (Bounded a, Integral a) => String -> Text -> Parser a
228−parseBoundedIntegralText name t =
229− prependContext name $
230− parseScientificText t >>= parseBoundedIntegralFromScientific
215+parseBoundedIntegralText expected t =
216+ parseScientificText t >>= parseBoundedIntegralFromScientific expected
231217
232218parseOptionalFieldWith :: (Value -> Parser (Maybe a))
233219 -> Object -> Text -> Parser (Maybe a)
@@ -287,21 +273,14 @@ genericLiftParseJSON opts pj pjl = fmap to1 . gParseJSON opts (From1Args pj pjl)
287273--
288274-- The basic ways to signal a failed conversion are as follows:
289275--
290−-- * 'fail' yields a custom error message: it is the recommended way of
291−-- reporting a failure;
292−--
293−-- * 'Control.Applicative.empty' (or 'Control.Monad.mzero') is uninformative:
294−-- use it when the error is meant to be caught by some @('<|>')@;
276+-- * 'empty' and 'mzero' work, but are terse and uninformative
295277--
296−-- * 'typeMismatch' can be used to report a failure when the encountered value
297−-- is not of the expected JSON type; 'unexpected' is an appropriate alternative
298−-- when more than one type may be expected, or to keep the expected type
299−-- implicit.
278+-- * 'fail' yields a custom error message
300279--
301−-- 'prependFailure' (or 'modifyFailure') add more information to a parser's
302−-- error messages.
280+-- * 'typeMismatch' produces an informative message for cases when the
281+-- value encountered is not of the expected type
303282--
304−-- An example type and instance using 'typeMismatch' and 'prependFailure':
283+-- An example type and instance:
305284--
306285-- @
307286-- \-- Allow ourselves to write 'Text' literals.
@@ -309,30 +288,15 @@ genericLiftParseJSON opts pj pjl = fmap to1 . gParseJSON opts (From1Args pj pjl)
309288--
310289-- data Coord = Coord { x :: Double, y :: Double }
311290--
312−-- instance 'FromJSON' Coord where
313−-- 'parseJSON' ('Object' v) = Coord
314−-- '<$>' v '.:' \"x\"
315−-- '<*>' v '.:' \"y\"
316−--
317−-- \-- We do not expect a non-'Object' value here.
318−-- \-- We could use 'Control.Applicative.empty' to fail, but 'typeMismatch'
319−-- \-- gives a much more informative error message.
320−-- 'parseJSON' invalid =
321−-- 'prependFailure' "parsing Coord failed, "
322−-- ('typeMismatch' \"Object\" invalid)
323−-- @
324−--
325−-- For this common case of only being concerned with a single
326−-- type of JSON value, the functions 'withObject', 'withScientific', etc.
327−-- are provided. Their use is to be preferred when possible, since
328−-- they are more terse. Using 'withObject', we can rewrite the above instance
329−-- (assuming the same language extension and data type) as:
291+-- instance FromJSON Coord where
292+-- parseJSON ('Object' v) = Coord '<$>'
293+-- v '.:' \"x\" '<*>'
294+-- v '.:' \"y\"
330295--
331−-- @
332−-- instance 'FromJSON' Coord where
333−-- 'parseJSON' = 'withObject' \"Coord\" $ \\v -> Coord
334−-- '<$>' v '.:' \"x\"
335−-- '<*>' v '.:' \"y\"
296+-- \-- We do not expect a non-'Object' value here.
297+-- \-- We could use 'mzero' to fail, but 'typeMismatch'
298+-- \-- gives a much more informative error message.
299+-- parseJSON invalid = 'typeMismatch' \"Coord\" invalid
336300-- @
337301--
338302-- Instead of manually writing your 'FromJSON' instance, there are two options
@@ -340,7 +304,7 @@ genericLiftParseJSON opts pj pjl = fmap to1 . gParseJSON opts (From1Args pj pjl)
340304--
341305-- * "Data.Aeson.TH" provides Template Haskell functions which will derive an
342306-- instance at compile time. The generated instance is optimized for your type
343−-- so it will probably be more efficient than the following option.
307+-- so will probably be more efficient than the following two options:
344308--
345309-- * The compiler can provide a default generic implementation for
346310-- 'parseJSON'.
@@ -358,21 +322,18 @@ genericLiftParseJSON opts pj pjl = fmap to1 . gParseJSON opts (From1Args pj pjl)
358322--
359323-- data Coord = Coord { x :: Double, y :: Double } deriving 'Generic'
360324--
361−-- instance 'FromJSON' Coord
325+-- instance FromJSON Coord
362326-- @
363327--
364−-- The default implementation will be equivalent to
365−-- @parseJSON = 'genericParseJSON' 'defaultOptions'@; if you need different
366−-- options, you can customize the generic decoding by defining:
328+-- If @DefaultSignatures@ doesn't give exactly the results you want,
329+-- you can customize the generic decoding with only a tiny amount of
330+-- effort, using 'genericParseJSON' with your preferred 'Options':
367331--
368332-- @
369−-- customOptions = 'defaultOptions'
370−-- { 'fieldLabelModifier' = 'map' 'Data.Char.toUpper'
371−-- }
372−--
373−-- instance 'FromJSON' Coord where
374−-- 'parseJSON' = 'genericParseJSON' customOptions
333+-- instance FromJSON Coord where
334+-- parseJSON = 'genericParseJSON' 'defaultOptions'
375335-- @
336+
376337class FromJSON a where
377338 parseJSON :: Value -> Parser a
378339
@@ -380,11 +341,13 @@ class FromJSON a where
380341 parseJSON = genericParseJSON defaultOptions
381342
382343 parseJSONList :: Value -> Parser [a]
383− parseJSONList = withArray "[]" $ \a ->
384− zipWithM (parseIndexedJSON parseJSON) [0..]
344+ parseJSONList (Array a)
345+ = zipWithM (parseIndexedJSON parseJSON) [0..]
385346 . V.toList
386347 $ a
387348
349+ parseJSONList v = typeMismatch "[a]" v
350+
388351-------------------------------------------------------------------------------
389352-- Classes and types for map keys
390353-------------------------------------------------------------------------------
@@ -396,16 +359,6 @@ class FromJSON a where
396359-- > newtype SomeId = SomeId { getSomeId :: Text }
397360-- > deriving (Eq,Ord,Hashable,FromJSONKey)
398361--
399−-- If you have a sum of nullary constructors, you may use the generic
400−-- implementation:
401−--
402−-- @
403−-- data Color = Red | Green | Blue
404−-- deriving Generic
405−--
406−-- instance 'FromJSONKey' Color where
407−-- 'fromJSONKey' = 'genericFromJSONKey' 'defaultJSONKeyOptions'
408−-- @
409362class FromJSONKey a where
410363 -- | Strategy for parsing the key of a map-like container.
411364 fromJSONKey :: FromJSONKeyFunction a
@@ -428,7 +381,11 @@ class FromJSONKey a where
428381-- At the moment this type is intentionally not exported. 'FromJSONKeyFunction'
429382-- can be inspected, but cannot be constructed.
430383data CoerceText a where
384+#if HAS_COERCIBLE
431385 CoerceText :: Coercible Text a => CoerceText a
386+#else
387+ CoerceText :: CoerceText a
388+#endif
432389
433390-- | This type is related to 'ToJSONKeyFunction'. If 'FromJSONKeyValue' is used in the
434391-- 'FromJSONKey' instance, then 'ToJSONKeyValue' should be used in the 'ToJSONKey'
@@ -448,7 +405,7 @@ data FromJSONKeyFunction a
448405
449406-- | Only law abiding up to interpretation
450407instance Functor FromJSONKeyFunction where
451− fmap h (FromJSONKeyCoerce CoerceText) = FromJSONKeyText (h . coerce)
408+ fmap h (FromJSONKeyCoerce CoerceText) = FromJSONKeyText (h . coerce')
452409 fmap h (FromJSONKeyText f) = FromJSONKeyText (h . f)
453410 fmap h (FromJSONKeyTextParser f) = FromJSONKeyTextParser (fmap h . f)
454411 fmap h (FromJSONKeyValue f) = FromJSONKeyValue (fmap h . f)
@@ -462,7 +419,9 @@ instance Functor FromJSONKeyFunction where
462419--
463420-- On pre GHC 7.8 this is unconstrainted function.
464421fromJSONKeyCoerce ::
422+#if HAS_COERCIBLE
465423 Coercible Text a =>
424+#endif
466425 FromJSONKeyFunction a
467426fromJSONKeyCoerce = FromJSONKeyCoerce CoerceText
468427
@@ -470,91 +429,60 @@ fromJSONKeyCoerce = FromJSONKeyCoerce CoerceText
470429--
471430-- See note on 'fromJSONKeyCoerce'.
472431coerceFromJSONKeyFunction ::
432+#if HAS_COERCIBLE
473433 Coercible a b =>
434+#endif
474435 FromJSONKeyFunction a -> FromJSONKeyFunction b
436+#if HAS_COERCIBLE
475437coerceFromJSONKeyFunction = coerce
438+#else
439+coerceFromJSONKeyFunction (FromJSONKeyCoerce CoerceText) = FromJSONKeyCoerce CoerceText
440+coerceFromJSONKeyFunction (FromJSONKeyText f) = FromJSONKeyText (coerce' . f)
441+coerceFromJSONKeyFunction (FromJSONKeyTextParser f) = FromJSONKeyTextParser (fmap coerce' . f)
442+coerceFromJSONKeyFunction (FromJSONKeyValue f) = FromJSONKeyValue (fmap coerce' . f)
443+#endif
476444
477445{-# RULES
478446 "FromJSONKeyCoerce: fmap id" forall (x :: FromJSONKeyFunction a).
479447 fmap id x = x
480448 #-}
449+#if HAS_COERCIBLE
481450{-# RULES
482451 "FromJSONKeyCoerce: fmap coerce" forall x .
483452 fmap coerce x = coerceFromJSONKeyFunction x
484453 #-}
454+#endif
485455
486456-- | Same as 'fmap'. Provided for the consistency with 'ToJSONKeyFunction'.
487457mapFromJSONKeyFunction :: (a -> b) -> FromJSONKeyFunction a -> FromJSONKeyFunction b
488458mapFromJSONKeyFunction = fmap
489459
490−-- | 'fromJSONKey' for 'Generic' types.
491−-- These types must be sums of nullary constructors, whose names will be used
492−-- as keys for JSON objects.
493−--
494−-- See also 'genericToJSONKey'.
495−--
496−-- === __Example__
497−--
498−-- @
499−-- data Color = Red | Green | Blue
500−-- deriving 'Generic'
501−--
502−-- instance 'FromJSONKey' Color where
503−-- 'fromJSONKey' = 'genericFromJSONKey' 'defaultJSONKeyOptions'
504−-- @
505−genericFromJSONKey :: forall a. (Generic a, GFromJSONKey (Rep a))
506− => JSONKeyOptions
507− -> FromJSONKeyFunction a
508−genericFromJSONKey opts = FromJSONKeyTextParser $ \t ->
509− case parseSumFromString (keyModifier opts) t of
510− Nothing -> fail $
511− "invalid key " ++ show t ++ ", expected one of " ++ show cnames
512− Just k -> pure (to k)
513− where
514− cnames = unTagged2 (constructorTags (keyModifier opts) :: Tagged2 (Rep a) [String])
515−
516−class (ConstructorNames f, SumFromString f) => GFromJSONKey f where
517−instance (ConstructorNames f, SumFromString f) => GFromJSONKey f where
518−
519460-------------------------------------------------------------------------------
520461-- Functions needed for documentation
521462-------------------------------------------------------------------------------
522463
523464-- | Fail parsing due to a type mismatch, with a descriptive message.
524465--
525−-- The following wrappers should generally be prefered:
526−-- 'withObject', 'withArray', 'withText', 'withBool'.
527−--
528−-- ==== Error message example
466+-- Example usage:
529467--
530−-- > typeMismatch "Object" (String "oops")
531−-- > -- Error: "expected Object, but encountered String"
532−typeMismatch :: String -- ^ The name of the JSON type being parsed
533− -- (@\"Object\"@, @\"Array\"@, @\"String\"@, @\"Number\"@,
534− -- @\"Boolean\"@, or @\"Null\"@).
468+-- @
469+-- instance FromJSON Coord where
470+-- parseJSON ('Object' v) = {- type matches, life is good -}
471+-- parseJSON wat = 'typeMismatch' \"Coord\" wat
472+-- @
473+typeMismatch :: String -- ^ The name of the type you are trying to parse.
535474 -> Value -- ^ The actual value encountered.
536475 -> Parser a
537476typeMismatch expected actual =
538− fail $ "expected " ++ expected ++ ", but encountered " ++ typeOf actual
539−
540−-- | Fail parsing due to a type mismatch, when the expected types are implicit.
541−--
542−-- ==== Error message example
543−--
544−-- > unexpected (String "oops")
545−-- > -- Error: "unexpected String"
546−unexpected :: Value -> Parser a
547−unexpected actual = fail $ "unexpected " ++ typeOf actual
548−
549−-- | JSON type of a value, name of the head constructor.
550−typeOf :: Value -> String
551−typeOf v = case v of
552− Object _ -> "Object"
553− Array _ -> "Array"
554− String _ -> "String"
555− Number _ -> "Number"
556− Bool _ -> "Boolean"
557− Null -> "Null"
477+ fail $ "expected " ++ expected ++ ", encountered " ++ name
478+ where
479+ name = case actual of
480+ Object _ -> "Object"
481+ Array _ -> "Array"
482+ String _ -> "String"
483+ Number _ -> "Number"
484+ Bool _ -> "Boolean"
485+ Null -> "Null"
558486
559487-------------------------------------------------------------------------------
560488-- Lifings of FromJSON and ToJSON to unary and binary type constructors
@@ -567,7 +495,7 @@ typeOf v = case v of
567495--
568496-- * "Data.Aeson.TH" provides Template Haskell functions which will derive an
569497-- instance at compile time. The generated instance is optimized for your type
570−-- so it will probably be more efficient than the following option.
498+-- so will probably be more efficient than the following two options:
571499--
572500-- * The compiler can provide a default generic implementation for
573501-- 'liftParseJSON'.
@@ -585,20 +513,16 @@ typeOf v = case v of
585513--
586514-- data Pair a b = Pair { pairFst :: a, pairSnd :: b } deriving 'Generic1'
587515--
588−-- instance 'FromJSON' a => 'FromJSON1' (Pair a)
516+-- instance FromJSON a => FromJSON1 (Pair a)
589517-- @
590518--
591−-- If the default implementation doesn't give exactly the results you want,
519+-- If @DefaultSignatures@ doesn't give exactly the results you want,
592520-- you can customize the generic decoding with only a tiny amount of
593521-- effort, using 'genericLiftParseJSON' with your preferred 'Options':
594522--
595523-- @
596−-- customOptions = 'defaultOptions'
597−-- { 'fieldLabelModifier' = 'map' 'Data.Char.toUpper'
598−-- }
599−--
600−-- instance 'FromJSON' a => 'FromJSON1' (Pair a) where
601−-- 'liftParseJSON' = 'genericLiftParseJSON' customOptions
524+-- instance FromJSON a => FromJSON1 (Pair a) where
525+-- liftParseJSON = 'genericLiftParseJSON' 'defaultOptions'
602526-- @
603527class FromJSON1 f where
604528 liftParseJSON :: (Value -> Parser a) -> (Value -> Parser [a]) -> Value -> Parser (f a)
@@ -635,8 +559,9 @@ class FromJSON2 f where
635559 -> (Value -> Parser b)
636560 -> (Value -> Parser [b])
637561 -> Value -> Parser [f a b]
638− liftParseJSONList2 fa ga fb gb = withArray "[]" $ \vals ->
639− fmap V.toList (V.mapM (liftParseJSON2 fa ga fb gb) vals)
562+ liftParseJSONList2 fa ga fb gb v = case v of
563+ Array vals -> fmap V.toList (V.mapM (liftParseJSON2 fa ga fb gb) vals)
564+ _ -> typeMismatch "[a]" v
640565
641566-- | Lift the standard 'parseJSON' function through the type constructor.
642567parseJSON2 :: (FromJSON2 f, FromJSON a, FromJSON b) => Value -> Parser (f a b)
@@ -650,7 +575,7 @@ parseJSON2 = liftParseJSON2 parseJSON parseJSONList parseJSON parseJSONList
650575-- | Helper function to use with 'liftParseJSON'. See 'Data.Aeson.ToJSON.listEncoding'.
651576listParser :: (Value -> Parser a) -> Value -> Parser [a]
652577listParser f (Array xs) = fmap V.toList (V.mapM f xs)
653−listParser _ v = typeMismatch "Array" v
578+listParser _ v = typeMismatch "[a]" v
654579{-# INLINE listParser #-}
655580
656581-------------------------------------------------------------------------------
@@ -668,139 +593,48 @@ instance (FromJSON a) => FromJSON [a] where
668593-- Functions
669594-------------------------------------------------------------------------------
670595
671−-- | Add context to a failure message, indicating the name of the structure
672−-- being parsed.
673−--
674−-- > prependContext "MyType" (fail "[error message]")
675−-- > -- Error: "parsing MyType failed, [error message]"
676−prependContext :: String -> Parser a -> Parser a
677−prependContext name = prependFailure ("parsing " ++ name ++ " failed, ")
678−
679−-- | @'withObject' name f value@ applies @f@ to the 'Object' when @value@
680−-- is an 'Data.Aeson.Object' and fails otherwise.
681−--
682−-- ==== Error message example
683−--
684−-- > withObject "MyType" f (String "oops")
685−-- > -- Error: "parsing MyType failed, expected Object, but encountered String"
596+-- | @withObject expected f value@ applies @f@ to the 'Object' when @value@ is an @Object@
597+-- and fails using @'typeMismatch' expected@ otherwise.
686598withObject :: String -> (Object -> Parser a) -> Value -> Parser a
687−withObject _ f (Object obj) = f obj
688−withObject name _ v = prependContext name (typeMismatch "Object" v)
599+withObject _ f (Object obj) = f obj
600+withObject expected _ v = typeMismatch expected v
689601{-# INLINE withObject #-}
690602
691−-- | @'withText' name f value@ applies @f@ to the 'Text' when @value@ is a
692−-- 'Data.Aeson.String' and fails otherwise.
693−--
694−-- ==== Error message example
695−--
696−-- > withText "MyType" f Null
697−-- > -- Error: "parsing MyType failed, expected String, but encountered Null"
603+-- | @withText expected f value@ applies @f@ to the 'Text' when @value@ is a @String@
604+-- and fails using @'typeMismatch' expected@ otherwise.
698605withText :: String -> (Text -> Parser a) -> Value -> Parser a
699−withText _ f (String txt) = f txt
700−withText name _ v = prependContext name (typeMismatch "String" v)
606+withText _ f (String txt) = f txt
607+withText expected _ v = typeMismatch expected v
701608{-# INLINE withText #-}
702609
703−-- | @'withArray' expected f value@ applies @f@ to the 'Array' when @value@ is
704−-- an 'Data.Aeson.Array' and fails otherwise.
705−--
706−-- ==== Error message example
707−--
708−-- > withArray "MyType" f (String "oops")
709−-- > -- Error: "parsing MyType failed, expected Array, but encountered String"
610+-- | @withArray expected f value@ applies @f@ to the 'Array' when @value@ is an @Array@
611+-- and fails using @'typeMismatch' expected@ otherwise.
710612withArray :: String -> (Array -> Parser a) -> Value -> Parser a
711−withArray _ f (Array arr) = f arr
712−withArray name _ v = prependContext name (typeMismatch "Array" v)
613+withArray _ f (Array arr) = f arr
614+withArray expected _ v = typeMismatch expected v
713615{-# INLINE withArray #-}
714616
715−-- | @'withScientific' name f value@ applies @f@ to the 'Scientific' number
716−-- when @value@ is a 'Data.Aeson.Number' and fails using 'typeMismatch'
717−-- otherwise.
718−--
719−-- /Warning/: If you are converting from a scientific to an unbounded
720−-- type such as 'Integer' you may want to add a restriction on the
721−-- size of the exponent (see 'withBoundedScientific') to prevent
722−-- malicious input from filling up the memory of the target system.
723−--
724−-- ==== Error message example
725−--
726−-- > withScientific "MyType" f (String "oops")
727−-- > -- Error: "parsing MyType failed, expected Number, but encountered String"
617+-- | @withNumber expected f value@ applies @f@ to the 'Number' when @value@ is a 'Number'.
618+-- and fails using @'typeMismatch' expected@ otherwise.
619+withNumber :: String -> (Number -> Parser a) -> Value -> Parser a
620+withNumber expected f = withScientific expected (f . scientificToNumber)
621+{-# INLINE withNumber #-}
622+{-# DEPRECATED withNumber "Use withScientific instead" #-}
623+
624+-- | @withScientific expected f value@ applies @f@ to the 'Scientific' number when @value@ is a 'Number'.
625+-- and fails using @'typeMismatch' expected@ otherwise.
728626withScientific :: String -> (Scientific -> Parser a) -> Value -> Parser a
729−withScientific _ f (Number scientific) = f scientific
730−withScientific name _ v = prependContext name (typeMismatch "Number" v)
627+withScientific _ f (Number scientific) = f scientific
628+withScientific expected _ v = typeMismatch expected v
731629{-# INLINE withScientific #-}
732630
733−-- | A variant of 'withScientific' which doesn't use 'prependContext', so that
734−-- such context can be added separately in a way that also applies when the
735−-- continuation @f :: Scientific -> Parser a@ fails.
736−--
737−-- /Warning/: If you are converting from a scientific to an unbounded
738−-- type such as 'Integer' you may want to add a restriction on the
739−-- size of the exponent (see 'withBoundedScientific') to prevent
740−-- malicious input from filling up the memory of the target system.
741−--
742−-- ==== Error message examples
743−--
744−-- > withScientific' f (String "oops")
745−-- > -- Error: "unexpected String"
746−-- >
747−-- > prependContext "MyType" (withScientific' f (String "oops"))
748−-- > -- Error: "parsing MyType failed, unexpected String"
749−withScientific' :: (Scientific -> Parser a) -> Value -> Parser a
750−withScientific' f v = case v of
751− Number n -> f n
752− _ -> typeMismatch "Number" v
753−{-# INLINE withScientific' #-}
754−
755−-- | @'withBoundedScientific' name f value@ applies @f@ to the 'Scientific' number
756−-- when @value@ is a 'Number' with exponent less than or equal to 1024.
757−withBoundedScientific :: String -> (Scientific -> Parser a) -> Value -> Parser a
758−withBoundedScientific name f v = withBoundedScientific_ (prependContext name) f v
759−{-# INLINE withBoundedScientific #-}
760−
761−-- | A variant of 'withBoundedScientific' which doesn't use 'prependContext',
762−-- so that such context can be added separately in a way that also applies
763−-- when the continuation @f :: Scientific -> Parser a@ fails.
764−withBoundedScientific' :: (Scientific -> Parser a) -> Value -> Parser a
765−withBoundedScientific' f v = withBoundedScientific_ id f v
766−{-# INLINE withBoundedScientific' #-}
767−
768−-- | A variant of 'withBoundedScientific_' parameterized by a function to apply
769−-- to the 'Parser' in case of failure.
770−withBoundedScientific_ :: (Parser a -> Parser a) -> (Scientific -> Parser a) -> Value -> Parser a
771−withBoundedScientific_ whenFail f (Number scientific) =
772− if exp10 > 1024
773− then whenFail (fail msg)
774− else f scientific
775− where
776− exp10 = base10Exponent scientific
777− msg = "found a number with exponent " ++ show exp10 ++ ", but it must not be greater than 1024"
778−withBoundedScientific_ whenFail _ v =
779− whenFail (typeMismatch "Number" v)
780−{-# INLINE withBoundedScientific_ #-}
781−
782−-- | @'withBool' expected f value@ applies @f@ to the 'Bool' when @value@ is a
783−-- 'Boolean' and fails otherwise.
784−--
785−-- ==== Error message example
786−--
787−-- > withBool "MyType" f (String "oops")
788−-- > -- Error: "parsing MyType failed, expected Boolean, but encountered String"
631+-- | @withBool expected f value@ applies @f@ to the 'Bool' when @value@ is a @Bool@
632+-- and fails using @'typeMismatch' expected@ otherwise.
789633withBool :: String -> (Bool -> Parser a) -> Value -> Parser a
790−withBool _ f (Bool arr) = f arr
791−withBool name _ v = prependContext name (typeMismatch "Boolean" v)
634+withBool _ f (Bool arr) = f arr
635+withBool expected _ v = typeMismatch expected v
792636{-# INLINE withBool #-}
793637
794−-- | Decode a nested JSON-encoded string.
795−withEmbeddedJSON :: String -> (Value -> Parser a) -> Value -> Parser a
796−withEmbeddedJSON _ innerParser (String txt) =
797− either fail innerParser $ eitherDecode (L.fromStrict $ T.encodeUtf8 txt)
798− where
799− eitherDecode = eitherFormatError . eitherDecodeWith jsonEOF ifromJSON
800− eitherFormatError = either (Left . uncurry formatError) Right
801−withEmbeddedJSON name _ v = prependContext name (typeMismatch "String" v)
802−{-# INLINE withEmbeddedJSON #-}
803−
804638-- | Convert a value from JSON, failing if the types do not match.
805639fromJSON :: (FromJSON a) => Value -> Result a
806640fromJSON = parse parseJSON
@@ -819,7 +653,9 @@ ifromJSON = iparse parseJSON
819653-- in an object for it to be valid. If the key and value are
820654-- optional, use '.:?' instead.
821655(.:) :: (FromJSON a) => Object -> Text -> Parser a
822−(.:) = explicitParseField parseJSON
656+obj .: key = case H.lookup key obj of
657+ Nothing -> fail $ "key " ++ show key ++ " not present"
658+ Just v -> parseJSON v <?> Key key
823659{-# INLINE (.:) #-}
824660
825661-- | Retrieve the value associated with the given key of an 'Object'. The
@@ -830,7 +666,9 @@ ifromJSON = iparse parseJSON
830666-- from an object without affecting its validity. If the key and
831667-- value are mandatory, use '.:' instead.
832668(.:?) :: (FromJSON a) => Object -> Text -> Parser (Maybe a)
833−(.:?) = explicitParseFieldMaybe parseJSON
669+obj .:? key = case H.lookup key obj of
670+ Nothing -> pure Nothing
671+ Just v -> parseJSON v <?> Key key
834672{-# INLINE (.:?) #-}
835673
836674-- | Retrieve the value associated with the given key of an 'Object'.
@@ -840,47 +678,11 @@ ifromJSON = iparse parseJSON
840678-- This differs from '.:?' by attempting to parse 'Null' the same as any
841679-- other JSON value, instead of interpreting it as 'Nothing'.
842680(.:!) :: (FromJSON a) => Object -> Text -> Parser (Maybe a)
843−(.:!) = explicitParseFieldMaybe' parseJSON
681+obj .:! key = case H.lookup key obj of
682+ Nothing -> pure Nothing
683+ Just v -> Just <$> parseJSON v <?> Key key
844684{-# INLINE (.:!) #-}
845685
846−-- | Function variant of '.:'.
847−parseField :: (FromJSON a) => Object -> Text -> Parser a
848−parseField = (.:)
849−{-# INLINE parseField #-}
850−
851−-- | Function variant of '.:?'.
852−parseFieldMaybe :: (FromJSON a) => Object -> Text -> Parser (Maybe a)
853−parseFieldMaybe = (.:?)
854−{-# INLINE parseFieldMaybe #-}
855−
856−-- | Function variant of '.:!'.
857−parseFieldMaybe' :: (FromJSON a) => Object -> Text -> Parser (Maybe a)
858−parseFieldMaybe' = (.:!)
859−{-# INLINE parseFieldMaybe' #-}
860−
861−-- | Variant of '.:' with explicit parser function.
862−--
863−-- E.g. @'explicitParseField' 'parseJSON1' :: ('FromJSON1' f, 'FromJSON' a) -> 'Object' -> 'Text' -> 'Parser' (f a)@
864−explicitParseField :: (Value -> Parser a) -> Object -> Text -> Parser a
865−explicitParseField p obj key = case H.lookup key obj of
866− Nothing -> fail $ "key " ++ show key ++ " not found"
867− Just v -> p v <?> Key key
868−{-# INLINE explicitParseField #-}
869−
870−-- | Variant of '.:?' with explicit parser function.
871−explicitParseFieldMaybe :: (Value -> Parser a) -> Object -> Text -> Parser (Maybe a)
872−explicitParseFieldMaybe p obj key = case H.lookup key obj of
873− Nothing -> pure Nothing
874− Just v -> liftParseJSON p (listParser p) v <?> Key key -- listParser isn't used by maybe instance.
875−{-# INLINE explicitParseFieldMaybe #-}
876−
877−-- | Variant of '.:!' with explicit parser function.
878−explicitParseFieldMaybe' :: (Value -> Parser a) -> Object -> Text -> Parser (Maybe a)
879−explicitParseFieldMaybe' p obj key = case H.lookup key obj of
880− Nothing -> pure Nothing
881− Just v -> Just <$> p v <?> Key key
882−{-# INLINE explicitParseFieldMaybe' #-}
883−
884686-- | Helper for use in combination with '.:?' to provide default
885687-- values for optional JSON object fields.
886688--
@@ -903,47 +705,11 @@ pmval .!= val = fromMaybe val <$> pmval
903705-- Generic parseJSON
904706-------------------------------------------------------------------------------
905707
906−instance GFromJSON arity V1 where
907− -- Whereof we cannot format, thereof we cannot parse:
908− gParseJSON _ _ _ = fail "Attempted to parse empty type"
909−
910−
911708instance OVERLAPPABLE_ (GFromJSON arity a) => GFromJSON arity (M1 i c a) where
912709 -- Meta-information, which is not handled elsewhere, is just added to the
913710 -- parsed value:
914711 gParseJSON opts fargs = fmap M1 . gParseJSON opts fargs
915712
916−-- Information for error messages
917−
918−type TypeName = String
919−type ConName = String
920−
921−-- | Add the name of the type being parsed to a parser's error messages.
922−contextType :: TypeName -> Parser a -> Parser a
923−contextType = prependContext
924−
925−-- | Add the tagKey that will be looked up while building an ADT
926−-- | Produce the error equivalent to
927−-- | Left "Error in $: parsing T failed, expected an object with keys "tag" and
928−-- | "contents", where "tag" i-- |s associated to one of ["Foo", "Bar"],
929−-- | The parser returned error was: could not find key "tag"
930−contextTag :: Text -> [String] -> Parser a -> Parser a
931−contextTag tagKey cnames = prependFailure
932− ("expected Object with key \"" ++ unpack tagKey ++ "\"" ++
933− " containing one of " ++ show cnames ++ ", ")
934−
935−-- | Add the name of the constructor being parsed to a parser's error messages.
936−contextCons :: ConName -> TypeName -> Parser a -> Parser a
937−contextCons cname tname = prependContext (showCons cname tname)
938−
939−-- | Render a constructor as @\"MyType(MyConstructor)\"@.
940−showCons :: ConName -> TypeName -> String
941−showCons cname tname = tname ++ "(" ++ cname ++ ")"
942−
943−--------------------------------------------------------------------------------
944−
945−-- Parsing single fields
946−
947713instance (FromJSON a) => GFromJSON arity (K1 i a) where
948714 -- Constant values are decoded using their FromJSON instance:
949715 gParseJSON _opts _ = fmap K1 . parseJSON
@@ -958,499 +724,326 @@ instance (FromJSON1 f) => GFromJSON One (Rec1 f) where
958724 -- FromJSON1 instance:
959725 gParseJSON _opts (From1Args pj pjl) = fmap Rec1 . liftParseJSON pj pjl
960726
727+instance GFromJSON arity U1 where
728+ -- Empty constructors are expected to be encoded as an empty array:
729+ gParseJSON _opts _ v
730+ | isEmptyArray v = pure U1
731+ | otherwise = typeMismatch "unit constructor (U1)" v
732+
733+instance (ConsFromJSON arity a) => GFromJSON arity (C1 c a) where
734+ -- Constructors need to be decoded differently depending on whether they're
735+ -- a record or not. This distinction is made by consParseJSON:
736+ gParseJSON opts fargs = fmap M1 . consParseJSON opts fargs
737+
738+instance ( FromProduct arity a, FromProduct arity b
739+ , ProductSize a, ProductSize b
740+ ) => GFromJSON arity (a :*: b) where
741+ -- Products are expected to be encoded to an array. Here we check whether we
742+ -- got an array of the same size as the product, then parse each of the
743+ -- product's elements using parseProduct:
744+ gParseJSON opts fargs = withArray "product (:*:)" $ \arr ->
745+ let lenArray = V.length arr
746+ lenProduct = (unTagged2 :: Tagged2 (a :*: b) Int -> Int)
747+ productSize in
748+ if lenArray == lenProduct
749+ then parseProduct opts fargs arr 0 lenProduct
750+ else fail $ "When expecting a product of " ++ show lenProduct ++
751+ " values, encountered an Array of " ++ show lenArray ++
752+ " elements instead"
753+
754+instance ( AllNullary (a :+: b) allNullary
755+ , ParseSum arity (a :+: b) allNullary
756+ ) => GFromJSON arity (a :+: b) where
757+ -- If all constructors of a sum datatype are nullary and the
758+ -- 'allNullaryToStringTag' option is set they are expected to be
759+ -- encoded as strings. This distinction is made by 'parseSum':
760+ gParseJSON opts fargs =
761+ (unTagged :: Tagged allNullary (Parser ((a :+: b) d)) ->
762+ Parser ((a :+: b) d))
763+ . parseSum opts fargs
764+
961765instance (FromJSON1 f, GFromJSON One g) => GFromJSON One (f :.: g) where
962766 -- If an occurrence of the last type parameter is nested inside two
963767 -- composed types, it is decoded by using the outermost type's FromJSON1
964768 -- instance to generically decode the innermost type:
965769 gParseJSON opts fargs =
966− let gpj = gParseJSON opts fargs in
967− fmap Comp1 . liftParseJSON gpj (listParser gpj)
968−
969−--------------------------------------------------------------------------------
970−
971−instance (GFromJSON' arity a, Datatype d) => GFromJSON arity (D1 d a) where
972− -- Meta-information, which is not handled elsewhere, is just added to the
973− -- parsed value:
974− gParseJSON opts fargs = fmap M1 . gParseJSON' (tname :* opts :* fargs)
975− where
976− tname = moduleName proxy ++ "." ++ datatypeName proxy
977− proxy = undefined :: M1 _i d _f _p
978−
979−-- | 'GFromJSON', after unwrapping the 'D1' constructor, now carrying the data
980−-- type's name.
981−class GFromJSON' arity f where
982− gParseJSON' :: TypeName :* Options :* FromArgs arity a
983− -> Value
984− -> Parser (f a)
985−
986−-- | Single constructor.
987−instance ( ConsFromJSON arity a
988− , AllNullary (C1 c a) allNullary
989− , ParseSum arity (C1 c a) allNullary
990− , Constructor c
991− ) => GFromJSON' arity (C1 c a) where
992− -- The option 'tagSingleConstructors' determines whether to wrap
993− -- a single-constructor type.
994− gParseJSON' p@(_ :* opts :* _)
995− | tagSingleConstructors opts
996− = (unTagged :: Tagged allNullary (Parser (C1 c a p)) -> Parser (C1 c a p))
997− . parseSum p
998− | otherwise = fmap M1 . consParseJSON (cname :* p)
999− where
1000− cname = conName (undefined :: M1 _i c _f _p)
1001−
1002−-- | Multiple constructors.
1003−instance ( AllNullary (a :+: b) allNullary
1004− , ParseSum arity (a :+: b) allNullary
1005− ) => GFromJSON' arity (a :+: b) where
1006− -- If all constructors of a sum datatype are nullary and the
1007− -- 'allNullaryToStringTag' option is set they are expected to be
1008− -- encoded as strings. This distinction is made by 'parseSum':
1009− gParseJSON' p =
1010− (unTagged :: Tagged allNullary (Parser ((a :+: b) _d)) ->
1011− Parser ((a :+: b) _d))
1012− . parseSum p
770+ let gpj = gParseJSON opts fargs in
771+ fmap Comp1 . liftParseJSON gpj (listParser gpj)
1013772
1014773--------------------------------------------------------------------------------
1015774
1016775class ParseSum arity f allNullary where
1017− parseSum :: TypeName :* Options :* FromArgs arity a
1018− -> Value
1019− -> Tagged allNullary (Parser (f a))
1020−
1021−instance ( ConstructorNames f
1022− , SumFromString f
1023− , FromPair arity f
1024− , FromTaggedObject arity f
1025− , FromUntaggedValue arity f
1026− ) => ParseSum arity f True where
1027− parseSum p@(tname :* opts :* _)
1028− | allNullaryToStringTag opts = Tagged . parseAllNullarySum tname opts
1029− | otherwise = Tagged . parseNonAllNullarySum p
1030−
1031−instance ( ConstructorNames f
1032− , FromPair arity f
1033− , FromTaggedObject arity f
1034− , FromUntaggedValue arity f
1035− ) => ParseSum arity f False where
1036− parseSum p = Tagged . parseNonAllNullarySum p
776+ parseSum :: Options -> FromArgs arity a
777+ -> Value -> Tagged allNullary (Parser (f a))
778+
779+instance ( SumFromString (a :+: b)
780+ , FromPair arity (a :+: b)
781+ , FromTaggedObject arity (a :+: b)
782+ , FromUntaggedValue arity (a :+: b)
783+ ) => ParseSum arity (a :+: b) True where
784+ parseSum opts fargs
785+ | allNullaryToStringTag opts = Tagged . parseAllNullarySum opts
786+ | otherwise = Tagged . parseNonAllNullarySum opts fargs
787+
788+instance ( FromPair arity (a :+: b)
789+ , FromTaggedObject arity (a :+: b)
790+ , FromUntaggedValue arity (a :+: b)
791+ ) => ParseSum arity (a :+: b) False where
792+ parseSum opts fargs = Tagged . parseNonAllNullarySum opts fargs
1037793
1038794--------------------------------------------------------------------------------
1039795
1040−parseAllNullarySum :: (SumFromString f, ConstructorNames f)
1041− => TypeName -> Options -> Value -> Parser (f a)
1042−parseAllNullarySum tname opts =
1043− withText tname $ \tag ->
1044− maybe (badTag tag) return $
1045− parseSumFromString modifier tag
1046− where
1047− badTag tag = failWithCTags tname modifier $ \cnames ->
1048− "expected one of the tags " ++ show cnames ++
1049− ", but found tag " ++ show tag
1050− modifier = constructorTagModifier opts
1051−
1052−-- | Fail with an informative error message about a mismatched tag.
1053−-- The error message is parameterized by the list of expected tags,
1054−-- to be inferred from the result type of the parser.
1055−failWithCTags
1056− :: forall f a t. ConstructorNames f
1057− => TypeName -> (String -> t) -> ([t] -> String) -> Parser (f a)
1058−failWithCTags tname modifier f =
1059− contextType tname . fail $ f cnames
1060− where
1061− cnames = unTagged2 (constructorTags modifier :: Tagged2 f [t])
796+parseAllNullarySum :: SumFromString f => Options -> Value -> Parser (f a)
797+parseAllNullarySum opts = withText "Text" $ \key ->
798+ maybe (notFound key) return $
799+ parseSumFromString opts key
1062800
1063801class SumFromString f where
1064− parseSumFromString :: (String -> String) -> Text -> Maybe (f a)
802+ parseSumFromString :: Options -> Text -> Maybe (f a)
1065803
1066804instance (SumFromString a, SumFromString b) => SumFromString (a :+: b) where
1067805 parseSumFromString opts key = (L1 <$> parseSumFromString opts key) <|>
1068806 (R1 <$> parseSumFromString opts key)
1069807
1070808instance (Constructor c) => SumFromString (C1 c U1) where
1071− parseSumFromString modifier key
1072− | key == name = Just $ M1 U1
1073− | otherwise = Nothing
1074− where
1075− name = pack $ modifier $ conName (undefined :: M1 _i c _f _p)
1076−
1077−-- For genericFromJSONKey
1078−instance SumFromString a => SumFromString (D1 d a) where
1079− parseSumFromString modifier key = M1 <$> parseSumFromString modifier key
1080−
1081−-- | List of all constructor tags.
1082−constructorTags :: ConstructorNames a => (String -> t) -> Tagged2 a [t]
1083−constructorTags modifier =
1084− fmap DList.toList (constructorNames' modifier)
1085−
1086−-- | List of all constructor names of an ADT, after a given conversion
1087−-- function. (Better inlining.)
1088−class ConstructorNames a where
1089− constructorNames' :: (String -> t) -> Tagged2 a (DList.DList t)
1090−
1091−instance (ConstructorNames a, ConstructorNames b) => ConstructorNames (a :+: b) where
1092− constructorNames' = liftA2 append constructorNames' constructorNames'
1093− where
1094− append
1095− :: Tagged2 a (DList.DList t)
1096− -> Tagged2 b (DList.DList t)
1097− -> Tagged2 (a :+: b) (DList.DList t)
1098− append (Tagged2 xs) (Tagged2 ys) = Tagged2 (DList.append xs ys)
1099−
1100−instance Constructor c => ConstructorNames (C1 c a) where
1101− constructorNames' f = Tagged2 (pure (f cname))
1102− where
1103− cname = conName (undefined :: M1 _i c _f _p)
1104−
1105−-- For genericFromJSONKey
1106−instance ConstructorNames a => ConstructorNames (D1 d a) where
1107− constructorNames' = retag . constructorNames'
1108− where
1109− retag :: Tagged2 a u -> Tagged2 (D1 d a) u
1110− retag (Tagged2 x) = Tagged2 x
809+ parseSumFromString opts key | key == name = Just $ M1 U1
810+ | otherwise = Nothing
811+ where
812+ name = pack $ constructorTagModifier opts $
813+ conName (undefined :: t c U1 p)
1111814
1112815--------------------------------------------------------------------------------
1113−parseNonAllNullarySum :: forall f c arity.
1114− ( FromPair arity f
1115− , FromTaggedObject arity f
1116− , FromUntaggedValue arity f
1117− , ConstructorNames f
1118− ) => TypeName :* Options :* FromArgs arity c
1119− -> Value -> Parser (f c)
1120−parseNonAllNullarySum p@(tname :* opts :* _) =
816+
817+parseNonAllNullarySum :: ( FromPair arity (a :+: b)
818+ , FromTaggedObject arity (a :+: b)
819+ , FromUntaggedValue arity (a :+: b)
820+ ) => Options -> FromArgs arity c
821+ -> Value -> Parser ((a :+: b) c)
822+parseNonAllNullarySum opts fargs =
1121823 case sumEncoding opts of
1122824 TaggedObject{..} ->
1123− withObject tname $ \obj -> do
1124− tag <- contextType tname . contextTag tagKey cnames_ $ obj .: tagKey
1125− fromMaybe (badTag tag <?> Key tagKey) $
1126− parseFromTaggedObject (tag :* contentsFieldName :* p) obj
1127− where
1128− tagKey = pack tagFieldName
1129− badTag tag = failWith_ $ \cnames ->
1130− "expected tag field to be one of " ++ show cnames ++
1131− ", but found tag " ++ show tag
1132− cnames_ = unTagged2 (constructorTags (constructorTagModifier opts) :: Tagged2 f [String])
825+ withObject "Object" $ \obj -> do
826+ tag <- obj .: pack tagFieldName
827+ fromMaybe (notFound tag) $
828+ parseFromTaggedObject opts fargs contentsFieldName obj tag
1133829
1134830 ObjectWithSingleField ->
1135− withObject tname $ \obj -> case H.toList obj of
1136− [(tag, v)] -> maybe (badTag tag) (<?> Key tag) $
1137− parsePair (tag :* p) v
1138− _ -> contextType tname . fail $
1139− "expected an Object with a single pair, but found " ++
1140− show (H.size obj) ++ " pairs"
1141− where
1142− badTag tag = failWith_ $ \cnames ->
1143− "expected an Object with a single pair where the tag is one of " ++
1144− show cnames ++ ", but found tag " ++ show tag
831+ withObject "Object" $ \obj ->
832+ case H.toList obj of
833+ [pair@(tag, _)] -> fromMaybe (notFound tag) $
834+ parsePair opts fargs pair
835+ _ -> fail "Object doesn't have a single field"
1145836
1146837 TwoElemArray ->
1147− withArray tname $ \arr -> case V.length arr of
1148− 2 | String tag <- V.unsafeIndex arr 0 ->
1149− maybe (badTag tag <?> Index 0) (<?> Index 1) $
1150− parsePair (tag :* p) (V.unsafeIndex arr 1)
1151− | otherwise ->
1152− contextType tname $
1153− fail "tag element is not a String" <?> Index 0
1154− len -> contextType tname . fail $
1155− "expected a 2-element Array, but encountered an Array of length " ++
1156− show len
1157− where
1158− badTag tag = failWith_ $ \cnames ->
1159− "expected tag of the 2-element Array to be one of " ++
1160− show cnames ++ ", but found tag " ++ show tag
838+ withArray "Array" $ \arr ->
839+ if V.length arr == 2
840+ then case V.unsafeIndex arr 0 of
841+ String tag -> fromMaybe (notFound tag) $
842+ parsePair opts fargs (tag, V.unsafeIndex arr 1)
843+ _ -> fail "First element is not a String"
844+ else fail "Array doesn't have 2 elements"
1161845
1162− UntaggedValue -> parseUntaggedValue p
1163− where
1164− failWith_ = failWithCTags tname (constructorTagModifier opts)
846+ UntaggedValue -> parseUntaggedValue opts fargs
1165847
1166848--------------------------------------------------------------------------------
1167849
1168850class FromTaggedObject arity f where
1169− -- The first two components of the parameter tuple are: the constructor tag
1170− -- to match against, and the contents field name.
1171− parseFromTaggedObject
1172− :: Text :* String :* TypeName :* Options :* FromArgs arity a
1173− -> Object
1174− -> Maybe (Parser (f a))
851+ parseFromTaggedObject :: Options -> FromArgs arity a
852+ -> String -> Object
853+ -> Text -> Maybe (Parser (f a))
1175854
1176855instance ( FromTaggedObject arity a, FromTaggedObject arity b) =>
1177856 FromTaggedObject arity (a :+: b) where
1178− parseFromTaggedObject p obj =
1179− (fmap L1 <$> parseFromTaggedObject p obj) <|>
1180− (fmap R1 <$> parseFromTaggedObject p obj)
857+ parseFromTaggedObject opts fargs contentsFieldName obj tag =
858+ (fmap L1 <$> parseFromTaggedObject opts fargs contentsFieldName obj tag) <|>
859+ (fmap R1 <$> parseFromTaggedObject opts fargs contentsFieldName obj tag)
1181860
1182−instance ( IsRecord f isRecord
1183− , FromTaggedObject' arity f isRecord
861+instance ( FromTaggedObject' arity f
1184862 , Constructor c
1185863 ) => FromTaggedObject arity (C1 c f) where
1186− parseFromTaggedObject (tag :* contentsFieldName :* p@(_ :* opts :* _))
1187− | tag == tag'
1188− = Just . fmap M1 .
1189− (unTagged :: Tagged isRecord (Parser (f a)) -> Parser (f a)) .
1190− parseFromTaggedObject' (contentsFieldName :* cname :* p)
1191− | otherwise = const Nothing
1192− where
1193− tag' = pack $ constructorTagModifier opts cname
1194− cname = conName (undefined :: M1 _i c _f _p)
864+ parseFromTaggedObject opts fargs contentsFieldName obj tag
865+ | tag == name = Just $ M1 <$> parseFromTaggedObject'
866+ opts fargs contentsFieldName obj
867+ | otherwise = Nothing
868+ where
869+ name = pack $ constructorTagModifier opts $
870+ conName (undefined :: t c f p)
1195871
1196872--------------------------------------------------------------------------------
1197873
1198−class FromTaggedObject' arity f isRecord where
1199− -- The first component of the parameter tuple is the contents field name.
1200− parseFromTaggedObject'
1201− :: String :* ConName :* TypeName :* Options :* FromArgs arity a
1202− -> Object -> Tagged isRecord (Parser (f a))
1203−
1204−instance (RecordFromJSON arity f, FieldNames f) => FromTaggedObject' arity f True where
1205− -- Records are unpacked in the tagged object
1206− parseFromTaggedObject' (_ :* p) = Tagged . recordParseJSON (True :* p)
1207−
1208−instance (ConsFromJSON arity f) => FromTaggedObject' arity f False where
1209− -- Nonnullary nonrecords are encoded in the contents field
1210− parseFromTaggedObject' p obj = Tagged $ do
1211− contents <- contextCons cname tname (obj .: key)
1212− consParseJSON p' contents <?> Key key
1213− where
1214− key = pack contentsFieldName
1215− contentsFieldName :* p'@(cname :* tname :* _) = p
874+class FromTaggedObject' arity f where
875+ parseFromTaggedObject' :: Options -> FromArgs arity a -> String
876+ -> Object -> Parser (f a)
877+
878+class FromTaggedObject'' arity f isRecord where
879+ parseFromTaggedObject'' :: Options -> FromArgs arity a -> String
880+ -> Object -> Tagged isRecord (Parser (f a))
881+
882+instance ( IsRecord f isRecord
883+ , FromTaggedObject'' arity f isRecord
884+ ) => FromTaggedObject' arity f where
885+ parseFromTaggedObject' opts fargs contentsFieldName =
886+ (unTagged :: Tagged isRecord (Parser (f a)) -> Parser (f a)) .
887+ parseFromTaggedObject'' opts fargs contentsFieldName
1216888
1217−instance OVERLAPPING_ FromTaggedObject' arity U1 False where
1218− -- Nullary constructors don't need a contents field
1219− parseFromTaggedObject' _ _ = Tagged (pure U1)
889+instance (FromRecord arity f) => FromTaggedObject'' arity f True where
890+ parseFromTaggedObject'' opts fargs _ =
891+ Tagged . parseRecord opts fargs Nothing
892+
893+instance (GFromJSON arity f) => FromTaggedObject'' arity f False where
894+ parseFromTaggedObject'' opts fargs contentsFieldName = Tagged .
895+ (gParseJSON opts fargs <=< (.: pack contentsFieldName))
896+
897+instance OVERLAPPING_ FromTaggedObject'' arity U1 False where
898+ parseFromTaggedObject'' _ _ _ _ = Tagged (pure U1)
1220899
1221900--------------------------------------------------------------------------------
1222901
1223−-- | Constructors need to be decoded differently depending on whether they're
1224−-- a record or not. This distinction is made by 'ConsParseJSON'.
1225902class ConsFromJSON arity f where
1226− consParseJSON
1227− :: ConName :* TypeName :* Options :* FromArgs arity a
1228− -> Value -> Parser (f a)
903+ consParseJSON :: Options -> FromArgs arity a
904+ -> Value -> Parser (f a)
1229905
1230906class ConsFromJSON' arity f isRecord where
1231− consParseJSON'
1232− :: ConName :* TypeName :* Options :* FromArgs arity a
1233− -> Value -> Tagged isRecord (Parser (f a))
907+ consParseJSON' :: Options -> FromArgs arity a
908+ -> Maybe Text -- ^ A dummy label
909+ -- (Nothing to use proper label)
910+ -> Value -> Tagged isRecord (Parser (f a))
1234911
1235912instance ( IsRecord f isRecord
1236913 , ConsFromJSON' arity f isRecord
1237914 ) => ConsFromJSON arity f where
1238− consParseJSON p =
1239− (unTagged :: Tagged isRecord (Parser (f a)) -> Parser (f a))
1240− . consParseJSON' p
915+ consParseJSON opts fargs v = let
916+ (v2,lab) = case (unwrapUnaryRecords opts,isUnary (undefined :: f a)) of
917+ -- use a dummy object with a dummy label
918+ (True,True) -> (object [(pack "dummy",v)], Just $ pack "dummy")
919+ _ ->(v,Nothing)
920+ in (unTagged :: Tagged isRecord (Parser (f a)) -> Parser (f a))
921+ $ consParseJSON' opts fargs lab v2
1241922
1242−instance OVERLAPPING_
1243− ( GFromJSON arity a, RecordFromJSON arity (S1 s a)
1244− ) => ConsFromJSON' arity (S1 s a) True where
1245− consParseJSON' p@(cname :* tname :* opts :* fargs)
1246− | unwrapUnaryRecords opts = Tagged . fmap M1 . gParseJSON opts fargs
1247− | otherwise = Tagged . withObject (showCons cname tname) (recordParseJSON (False :* p))
1248923
1249−instance RecordFromJSON arity f => ConsFromJSON' arity f True where
1250− consParseJSON' p@(cname :* tname :* _) =
1251− Tagged . withObject (showCons cname tname) (recordParseJSON (False :* p))
1252−
1253−instance OVERLAPPING_
1254− ConsFromJSON' arity U1 False where
1255− -- Empty constructors are expected to be encoded as an empty array:
1256− consParseJSON' (cname :* tname :* _) v =
1257− Tagged . contextCons cname tname $ case v of
1258− Array a | V.null a -> pure U1
1259− | otherwise -> fail_ a
1260− _ -> typeMismatch "Array" v
1261− where
1262− fail_ a = fail $
1263− "expected an empty Array, but encountered an Array of length " ++
1264− show (V.length a)
1265−
1266−instance OVERLAPPING_
1267− GFromJSON arity f => ConsFromJSON' arity (S1 s f) False where
1268− consParseJSON' (_ :* _ :* opts :* fargs) =
1269− Tagged . fmap M1 . gParseJSON opts fargs
924+instance (FromRecord arity f) => ConsFromJSON' arity f True where
925+ consParseJSON' opts fargs mlab = Tagged . withObject "record (:*:)"
926+ (parseRecord opts fargs mlab)
1270927
1271−instance (ProductFromJSON arity f, ProductSize f
1272− ) => ConsFromJSON' arity f False where
1273− consParseJSON' p = Tagged . productParseJSON0 p
928+instance (GFromJSON arity f) => ConsFromJSON' arity f False where
929+ consParseJSON' opts fargs _ = Tagged . gParseJSON opts fargs
1274930
1275931--------------------------------------------------------------------------------
1276932
1277−class FieldNames f where
1278− fieldNames :: f a -> [Text] -> [Text]
933+class FromRecord arity f where
934+ parseRecord :: Options -> FromArgs arity a
935+ -> Maybe Text -- ^ A dummy label
936+ -- (Nothing to use proper label)
937+ -> Object -> Parser (f a)
1279938
1280−instance (FieldNames a, FieldNames b) => FieldNames (a :*: b) where
1281− fieldNames _ =
1282− fieldNames (undefined :: a x) .
1283− fieldNames (undefined :: b y)
1284−
1285−instance (Selector s) => FieldNames (S1 s f) where
1286− fieldNames _ = (pack (selName (undefined :: M1 _i s _f _p)) :)
1287−
1288−class RecordFromJSON arity f where
1289− recordParseJSON
1290− :: Bool :* ConName :* TypeName :* Options :* FromArgs arity a
1291− -> Object -> Parser (f a)
1292−
1293−instance ( FieldNames f
1294− , RecordFromJSON' arity f
1295− ) => RecordFromJSON arity f where
1296− recordParseJSON (fromTaggedSum :* p@(cname :* tname :* opts :* _)) =
1297− \obj -> checkUnknown obj >> recordParseJSON' p obj
1298− where
1299− knownFields :: H.HashMap Text ()
1300− knownFields = H.fromList $ map (,()) $
1301− fieldNames (undefined :: f a)
1302− [pack (tagFieldName (sumEncoding opts)) | fromTaggedSum]
1303− checkUnknown =
1304− if not (rejectUnknownFields opts)
1305− then \_ -> return ()
1306− else \obj -> case H.keys (H.difference obj knownFields) of
1307− [] -> return ()
1308− unknownFields -> contextCons cname tname $
1309− fail ("unknown fields: " ++ show unknownFields)
1310−
1311−class RecordFromJSON' arity f where
1312− recordParseJSON'
1313− :: ConName :* TypeName :* Options :* FromArgs arity a
1314− -> Object -> Parser (f a)
1315−
1316−instance ( RecordFromJSON' arity a
1317− , RecordFromJSON' arity b
1318− ) => RecordFromJSON' arity (a :*: b) where
1319− recordParseJSON' p obj =
1320− (:*:) <$> recordParseJSON' p obj
1321− <*> recordParseJSON' p obj
939+instance ( FromRecord arity a
940+ , FromRecord arity b
941+ ) => FromRecord arity (a :*: b) where
942+ parseRecord opts fargs _ obj =
943+ (:*:) <$> parseRecord opts fargs Nothing obj
944+ <*> parseRecord opts fargs Nothing obj
1322945
1323946instance OVERLAPPABLE_ (Selector s, GFromJSON arity a) =>
1324− RecordFromJSON' arity (S1 s a) where
1325− recordParseJSON' (cname :* tname :* opts :* fargs) obj = do
1326− fv <- contextCons cname tname (obj .: label)
1327− M1 <$> gParseJSON opts fargs fv <?> Key label
1328− where
1329− label = pack $ fieldLabelModifier opts sname
1330− sname = selName (undefined :: M1 _i s _f _p)
1331−
1332−instance INCOHERENT_ (Selector s, FromJSON a) =>
1333− RecordFromJSON' arity (S1 s (K1 i (Maybe a))) where
1334− recordParseJSON' (_ :* _ :* opts :* _) obj = M1 . K1 <$> obj .:? pack label
1335− where
1336− label = fieldLabelModifier opts sname
1337− sname = selName (undefined :: M1 _i s _f _p)
947+ FromRecord arity (S1 s a) where
948+ parseRecord opts fargs lab =
949+ (<?> Key label) . gParseJSON opts fargs <=< (.: label)
950+ where
951+ label = fromMaybe defLabel lab
952+ defLabel = pack . fieldLabelModifier opts $
953+ selName (undefined :: t s a p)
1338954
1339−-- Parse an Option like a Maybe.
1340955instance INCOHERENT_ (Selector s, FromJSON a) =>
1341− RecordFromJSON' arity (S1 s (K1 i (Semigroup.Option a))) where
1342− recordParseJSON' p obj = wrap <$> recordParseJSON' p obj
1343− where
1344− wrap :: S1 s (K1 i (Maybe a)) p -> S1 s (K1 i (Semigroup.Option a)) p
1345− wrap (M1 (K1 a)) = M1 (K1 (Semigroup.Option a))
956+ FromRecord arity (S1 s (K1 i (Maybe a))) where
957+ parseRecord _ _ (Just lab) obj = (M1 . K1) <$> obj .:? lab
958+ parseRecord opts _ Nothing obj = (M1 . K1) <$> obj .:? pack label
959+ where
960+ label = fieldLabelModifier opts $
961+ selName (undefined :: t s (K1 i (Maybe a)) p)
1346962
1347963--------------------------------------------------------------------------------
1348964
1349−productParseJSON0
1350− :: forall f arity a. (ProductFromJSON arity f, ProductSize f)
1351− => ConName :* TypeName :* Options :* FromArgs arity a
1352− -> Value -> Parser (f a)
1353− -- Products are expected to be encoded to an array. Here we check whether we
1354− -- got an array of the same size as the product, then parse each of the
1355− -- product's elements using productParseJSON:
1356−productParseJSON0 p@(cname :* tname :* _ :* _) =
1357− withArray (showCons cname tname) $ \arr ->
1358− let lenArray = V.length arr
1359− lenProduct = (unTagged2 :: Tagged2 f Int -> Int)
1360− productSize in
1361− if lenArray == lenProduct
1362− then productParseJSON p arr 0 lenProduct
1363− else contextCons cname tname $
1364− fail $ "expected an Array of length " ++ show lenProduct ++
1365− ", but encountered an Array of length " ++ show lenArray
1366−
1367−--
1368−
1369−class ProductFromJSON arity f where
1370− productParseJSON :: ConName :* TypeName :* Options :* FromArgs arity a
965+class FromProduct arity f where
966+ parseProduct :: Options -> FromArgs arity a
1371967 -> Array -> Int -> Int
1372968 -> Parser (f a)
1373969
1374−instance ( ProductFromJSON arity a
1375− , ProductFromJSON arity b
1376− ) => ProductFromJSON arity (a :*: b) where
1377− productParseJSON p arr ix len =
1378− (:*:) <$> productParseJSON p arr ix lenL
1379− <*> productParseJSON p arr ixR lenR
970+instance ( FromProduct arity a
971+ , FromProduct arity b
972+ ) => FromProduct arity (a :*: b) where
973+ parseProduct opts fargs arr ix len =
974+ (:*:) <$> parseProduct opts fargs arr ix lenL
975+ <*> parseProduct opts fargs arr ixR lenR
1380976 where
1381977 lenL = len `unsafeShiftR` 1
1382978 ixR = ix + lenL
1383979 lenR = len - lenL
1384980
1385−instance (GFromJSON arity a) => ProductFromJSON arity (S1 s a) where
1386− productParseJSON (_ :* _ :* opts :* fargs) arr ix _ =
1387− M1 <$> gParseJSON opts fargs (V.unsafeIndex arr ix) <?> Index ix
981+instance (GFromJSON arity a) => FromProduct arity (S1 s a) where
982+ parseProduct opts fargs arr ix _ =
983+ gParseJSON opts fargs $ V.unsafeIndex arr ix
1388984
1389985--------------------------------------------------------------------------------
1390986
1391987class FromPair arity f where
1392− -- The first component of the parameter tuple is the tag to match.
1393− parsePair :: Text :* TypeName :* Options :* FromArgs arity a
1394− -> Value
1395− -> Maybe (Parser (f a))
988+ parsePair :: Options -> FromArgs arity a
989+ -> Pair -> Maybe (Parser (f a))
1396990
1397991instance ( FromPair arity a
1398992 , FromPair arity b
1399993 ) => FromPair arity (a :+: b) where
1400− parsePair p pair =
1401− (fmap L1 <$> parsePair p pair) <|>
1402− (fmap R1 <$> parsePair p pair)
994+ parsePair opts fargs pair = (fmap L1 <$> parsePair opts fargs pair) <|>
995+ (fmap R1 <$> parsePair opts fargs pair)
1403996
1404997instance ( Constructor c
998+ , GFromJSON arity a
1405999 , ConsFromJSON arity a
14061000 ) => FromPair arity (C1 c a) where
1407− parsePair (tag :* p@(_ :* opts :* _)) v
1408− | tag == tag' = Just $ M1 <$> consParseJSON (cname :* p) v
1001+ parsePair opts fargs (tag, value)
1002+ | tag == tag' = Just $ gParseJSON opts fargs value
14091003 | otherwise = Nothing
1410− where
1411− tag' = pack $ constructorTagModifier opts cname
1412− cname = conName (undefined :: M1 _i c _a _p)
1004+ where
1005+ tag' = pack $ constructorTagModifier opts $
1006+ conName (undefined :: t c a p)
14131007
14141008--------------------------------------------------------------------------------
14151009
14161010class FromUntaggedValue arity f where
1417− parseUntaggedValue :: TypeName :* Options :* FromArgs arity a
1418− -> Value
1419− -> Parser (f a)
1011+ parseUntaggedValue :: Options -> FromArgs arity a
1012+ -> Value -> Parser (f a)
14201013
14211014instance
14221015 ( FromUntaggedValue arity a
14231016 , FromUntaggedValue arity b
14241017 ) => FromUntaggedValue arity (a :+: b)
14251018 where
1426− parseUntaggedValue p value =
1427− L1 <$> parseUntaggedValue p value <|>
1428− R1 <$> parseUntaggedValue p value
1019+ parseUntaggedValue opts fargs value =
1020+ L1 <$> parseUntaggedValue opts fargs value <|>
1021+ R1 <$> parseUntaggedValue opts fargs value
14291022
14301023instance OVERLAPPABLE_
1431− ( ConsFromJSON arity a
1432− , Constructor c
1024+ ( GFromJSON arity a
1025+ , ConsFromJSON arity a
14331026 ) => FromUntaggedValue arity (C1 c a)
14341027 where
1435− parseUntaggedValue p = fmap M1 . consParseJSON (cname :* p)
1436− where
1437− cname = conName (undefined :: M1 _i c _f _p)
1028+ parseUntaggedValue = gParseJSON
14381029
14391030instance OVERLAPPING_
14401031 ( Constructor c )
14411032 => FromUntaggedValue arity (C1 c U1)
14421033 where
1443− parseUntaggedValue (tname :* opts :* _) v =
1444− contextCons cname tname $ case v of
1445− String tag
1446− | tag == tag' -> pure $ M1 U1
1447− | otherwise -> fail_ tag
1448− _ -> typeMismatch "String" v
1449− where
1450− tag' = pack $ constructorTagModifier opts cname
1451− cname = conName (undefined :: M1 _i c _f _p)
1452− fail_ tag = fail $
1453− "expected tag " ++ show tag' ++ ", but found tag " ++ show tag
1034+ parseUntaggedValue opts _ (String s)
1035+ | s == pack (constructorTagModifier opts (conName (undefined :: t c U1 p))) =
1036+ pure $ M1 U1
1037+ | otherwise =
1038+ fail $ "Invalid tag: " ++ unpack s
1039+ parseUntaggedValue _ _ v = typeMismatch (conName (undefined :: t c U1 p)) v
1040+
1041+
1042+--------------------------------------------------------------------------------
1043+
1044+notFound :: Text -> Parser a
1045+notFound key = fail $ "The key \"" ++ unpack key ++ "\" was not found"
1046+{-# INLINE notFound #-}
14541047
14551048-------------------------------------------------------------------------------
14561049-- Instances
@@ -1508,20 +1101,17 @@ instance (FromJSON a, FromJSON b) => FromJSON (Either a b) where
15081101 parseJSON = parseJSON2
15091102 {-# INLINE parseJSON #-}
15101103
1511−instance FromJSON Void where
1512− parseJSON _ = fail "Cannot parse Void"
1513− {-# INLINE parseJSON #-}
1104+
15141105
15151106instance FromJSON Bool where
1516− parseJSON (Bool b) = pure b
1517− parseJSON v = typeMismatch "Bool" v
1107+ parseJSON = withBool "Bool" pure
15181108 {-# INLINE parseJSON #-}
15191109
15201110instance FromJSONKey Bool where
15211111 fromJSONKey = FromJSONKeyTextParser $ \t -> case t of
15221112 "true" -> pure True
15231113 "false" -> pure False
1524− _ -> fail $ "cannot parse key " ++ show t ++ " into Bool"
1114+ _ -> fail $ "Cannot parse key into Bool: " ++ T.unpack t
15251115
15261116instance FromJSON Ordering where
15271117 parseJSON = withText "Ordering" $ \s ->
@@ -1529,30 +1119,25 @@ instance FromJSON Ordering where
15291119 "LT" -> return LT
15301120 "EQ" -> return EQ
15311121 "GT" -> return GT
1532− _ -> fail $ "parsing Ordering failed, unexpected " ++ show s ++
1533− " (expected \"LT\", \"EQ\", or \"GT\")"
1122+ _ -> fail "Parsing Ordering value failed: expected \"LT\", \"EQ\", or \"GT\""
15341123
15351124instance FromJSON () where
15361125 parseJSON = withArray "()" $ \v ->
15371126 if V.null v
15381127 then pure ()
1539− else prependContext "()" $ fail "expected an empty array"
1128+ else fail "Expected an empty array"
15401129 {-# INLINE parseJSON #-}
15411130
15421131instance FromJSON Char where
1543− parseJSON = withText "Char" parseChar
1132+ parseJSON = withText "Char" $ \t ->
1133+ if T.compareLength t 1 == EQ
1134+ then pure $ T.head t
1135+ else fail "Expected a string of length 1"
15441136 {-# INLINE parseJSON #-}
15451137
1546− parseJSONList (String s) = pure (T.unpack s)
1547− parseJSONList v = typeMismatch "String" v
1138+ parseJSONList = withText "String" $ pure . T.unpack
15481139 {-# INLINE parseJSONList #-}
15491140
1550−parseChar :: Text -> Parser Char
1551−parseChar t =
1552− if T.compareLength t 1 == EQ
1553− then pure $ T.head t
1554− else prependContext "Char" $ fail "expected a string of length 1"
1555−
15561141instance FromJSON Double where
15571142 parseJSON = parseRealFloat "Double"
15581143 {-# INLINE parseJSON #-}
@@ -1564,6 +1149,12 @@ instance FromJSONKey Double where
15641149 "-Infinity" -> pure (negate 1/0)
15651150 _ -> Scientific.toRealFloat <$> parseScientificText t
15661151
1152+instance FromJSON Number where
1153+ parseJSON (Number s) = pure $ scientificToNumber s
1154+ parseJSON Null = pure (D (0/0))
1155+ parseJSON v = typeMismatch "Number" v
1156+ {-# INLINE parseJSON #-}
1157+
15671158instance FromJSON Float where
15681159 parseJSON = parseRealFloat "Float"
15691160 {-# INLINE parseJSON #-}
@@ -1576,30 +1167,17 @@ instance FromJSONKey Float where
15761167 _ -> Scientific.toRealFloat <$> parseScientificText t
15771168
15781169instance (FromJSON a, Integral a) => FromJSON (Ratio a) where
1579− parseJSON (Number x)
1580− | exp10 <= 1024
1581− , exp10 >= -1024 = return $! realToFrac x
1582− | otherwise = prependContext "Ratio" $ fail msg
1583− where
1584− exp10 = base10Exponent x
1585− msg = "found a number with exponent " ++ show exp10
1586− ++ ", but it must not be greater than 1024 or less than -1024"
1587− parseJSON o = objParser o
1588− where
1589− objParser = withObject "Rational" $ \obj -> do
1590− numerator <- obj .: "numerator"
1591− denominator <- obj .: "denominator"
1592− if denominator == 0
1593− then fail "Ratio denominator was 0"
1594− else pure $ numerator % denominator
1595− {-# INLINE parseJSON #-}
1596−
1597−-- | This instance includes a bounds check to prevent maliciously
1598−-- large inputs to fill up the memory of the target system. You can
1599−-- newtype 'Scientific' and provide your own instance using
1600−-- 'withScientific' if you want to allow larger inputs.
1170+ parseJSON = withObject "Rational" $ \obj ->
1171+ (%) <$> obj .: "numerator"
1172+ <*> obj .: "denominator"
1173+ {-# INLINE parseJSON #-}
1174+
1175+-- | /WARNING:/ Only parse fixed-precision numbers from trusted input
1176+-- since an attacker could easily fill up the memory of the target
1177+-- system by specifying a scientific number with a big exponent like
1178+-- @1e1000000000@.
16011179instance HasResolution a => FromJSON (Fixed a) where
1602− parseJSON = prependContext "Fixed" . withBoundedScientific' (pure . realToFrac)
1180+ parseJSON = withScientific "Fixed" $ pure . realToFrac
16031181 {-# INLINE parseJSON #-}
16041182
16051183instance FromJSON Int where
@@ -1609,10 +1187,10 @@ instance FromJSON Int where
16091187instance FromJSONKey Int where
16101188 fromJSONKey = FromJSONKeyTextParser $ parseBoundedIntegralText "Int"
16111189
1612−-- | This instance includes a bounds check to prevent maliciously
1613−-- large inputs to fill up the memory of the target system. You can
1614−-- newtype 'Scientific' and provide your own instance using
1615−-- 'withScientific' if you want to allow larger inputs.
1190+-- | /WARNING:/ Only parse Integers from trusted input since an
1191+-- attacker could easily fill up the memory of the target system by
1192+-- specifying a scientific number with a big exponent like
1193+-- @1e1000000000@.
16161194instance FromJSON Integer where
16171195 parseJSON = parseIntegral "Integer"
16181196 {-# INLINE parseJSON #-}
@@ -1621,21 +1199,16 @@ instance FromJSONKey Integer where
16211199 fromJSONKey = FromJSONKeyTextParser $ parseIntegralText "Integer"
16221200
16231201instance FromJSON Natural where
1624− parseJSON value = do
1625− integer <- parseIntegral "Natural" value
1626− parseNatural integer
1202+ parseJSON = withScientific "Natural" $ \s ->
1203+ if Scientific.coefficient s < 0
1204+ then fail $ "Expected a Natural number but got the negative number: " <> show s
1205+ else pure $ truncate s
16271206
16281207instance FromJSONKey Natural where
1629− fromJSONKey = FromJSONKeyTextParser $ \text -> do
1630− integer <- parseIntegralText "Natural" text
1631− parseNatural integer
1632−
1633−parseNatural :: Integer -> Parser Natural
1634−parseNatural integer =
1635− if integer < 0 then
1636− fail $ "parsing Natural failed, unexpected negative number " <> show integer
1637− else
1638− pure $ fromIntegral integer
1208+ fromJSONKey = FromJSONKeyTextParser $ \t -> parseScientificText t >>= \s ->
1209+ if Scientific.coefficient s < 0
1210+ then fail $ "Expected a Natural number but got the negative number: " <> show s
1211+ else pure $ truncate s
16391212
16401213instance FromJSON Int8 where
16411214 parseJSON = parseBoundedIntegral "Int8"
@@ -1700,9 +1273,6 @@ instance FromJSON Word64 where
17001273instance FromJSONKey Word64 where
17011274 fromJSONKey = FromJSONKeyTextParser $ parseBoundedIntegralText "Word64"
17021275
1703−instance FromJSON CTime where
1704− parseJSON = fmap CTime . parseJSON
1705− {-# INLINE parseJSON #-}
17061276
17071277instance FromJSON Text where
17081278 parseJSON = withText "Text" pure
@@ -1732,17 +1302,17 @@ parseVersionText = go . readP_to_S parseVersion . unpack
17321302 where
17331303 go [(v,[])] = return v
17341304 go (_ : xs) = go xs
1735− go _ = fail "parsing Version failed"
1305+ go _ = fail "could not parse Version"
17361306
17371307-------------------------------------------------------------------------------
17381308-- semigroups NonEmpty
17391309-------------------------------------------------------------------------------
17401310
17411311instance FromJSON1 NonEmpty where
1742− liftParseJSON p _ = withArray "NonEmpty" $
1312+ liftParseJSON p _ = withArray "NonEmpty a" $
17431313 (>>= ne) . Tr.sequence . zipWith (parseIndexedJSON p) [0..] . V.toList
17441314 where
1745− ne [] = fail "parsing NonEmpty failed, unexpected empty list"
1315+ ne [] = fail "Expected a NonEmpty but got an empty list"
17461316 ne (x:xs) = pure (x :| xs)
17471317 {-# INLINE liftParseJSON #-}
17481318
@@ -1763,7 +1333,7 @@ instance FromJSON Scientific where
17631333-------------------------------------------------------------------------------
17641334
17651335instance FromJSON1 DList.DList where
1766− liftParseJSON p _ = withArray "DList" $
1336+ liftParseJSON p _ = withArray "DList a" $
17671337 fmap DList.fromList .
17681338 Tr.sequence . zipWith (parseIndexedJSON p) [0..] . V.toList
17691339 {-# INLINE liftParseJSON #-}
@@ -1790,7 +1360,7 @@ instance (FromJSON a) => FromJSON (Identity a) where
17901360 parseJSONList = liftParseJSONList parseJSON parseJSONList
17911361 {-# INLINE parseJSONList #-}
17921362
1793−instance (FromJSONKey a) => FromJSONKey (Identity a) where
1363+instance (FromJSONKey a, FromJSON a) => FromJSONKey (Identity a) where
17941364 fromJSONKey = coerceFromJSONKeyFunction (fromJSONKey :: FromJSONKeyFunction a)
17951365 fromJSONKeyList = coerceFromJSONKeyFunction (fromJSONKeyList :: FromJSONKeyFunction [a])
17961366
@@ -1840,7 +1410,7 @@ instance (FromJSON1 f, FromJSON1 g) => FromJSON1 (Sum f g) where
18401410 inr = "InR"
18411411
18421412 liftParseJSON _ _ _ = fail $
1843− "parsing Sum failed, expected an object with a single property " ++
1413+ "expected an object with a single property " ++
18441414 "where the property key should be either " ++
18451415 "\"InL\" or \"InR\""
18461416 {-# INLINE liftParseJSON #-}
@@ -1854,7 +1424,7 @@ instance (FromJSON1 f, FromJSON1 g, FromJSON a) => FromJSON (Sum f g a) where
18541424-------------------------------------------------------------------------------
18551425
18561426instance FromJSON1 Seq.Seq where
1857− liftParseJSON p _ = withArray "Seq" $
1427+ liftParseJSON p _ = withArray "Seq a" $
18581428 fmap Seq.fromList .
18591429 Tr.sequence . zipWith (parseIndexedJSON p) [0..] . V.toList
18601430 {-# INLINE liftParseJSON #-}
@@ -1888,15 +1458,15 @@ instance FromJSON a => FromJSON (IntMap.IntMap a) where
18881458
18891459instance (FromJSONKey k, Ord k) => FromJSON1 (M.Map k) where
18901460 liftParseJSON p _ = case fromJSONKey of
1891− FromJSONKeyCoerce _ -> withObject "Map" $
1461+ FromJSONKeyCoerce _-> withObject "Map k v" $
18921462 fmap (H.foldrWithKey (M.insert . unsafeCoerce) M.empty) . H.traverseWithKey (\k v -> p v <?> Key k)
1893− FromJSONKeyText f -> withObject "Map" $
1463+ FromJSONKeyText f -> withObject "Map k v" $
18941464 fmap (H.foldrWithKey (M.insert . f) M.empty) . H.traverseWithKey (\k v -> p v <?> Key k)
1895− FromJSONKeyTextParser f -> withObject "Map" $
1465+ FromJSONKeyTextParser f -> withObject "Map k v" $
18961466 H.foldrWithKey (\k v m -> M.insert <$> f k <?> Key k <*> p v <?> Key k <*> m) (pure M.empty)
1897− FromJSONKeyValue f -> withArray "Map" $ \arr ->
1898− fmap M.fromList . Tr.sequence .
1899− zipWith (parseIndexedJSONPair f p) [0..] . V.toList $ arr
1467+ FromJSONKeyValue f -> withArray "Map k v" $ \arr ->
1468+ M.fromList <$> (Tr.sequence .
1469+ zipWith (parseIndexedJSONPair f p) [0..] . V.toList $ arr)
19001470 {-# INLINE liftParseJSON #-}
19011471
19021472instance (FromJSONKey k, Ord k, FromJSON v) => FromJSON (M.Map k v) where
@@ -1916,24 +1486,12 @@ instance (FromJSON v) => FromJSON (Tree.Tree v) where
19161486 parseJSON = parseJSON1
19171487 {-# INLINE parseJSON #-}
19181488
1919−-------------------------------------------------------------------------------
1920−-- uuid
1921−-------------------------------------------------------------------------------
1922−
1923−instance FromJSON UUID.UUID where
1924− parseJSON = withText "UUID" $
1925− maybe (fail "invalid UUID") pure . UUID.fromText
1926−
1927−instance FromJSONKey UUID.UUID where
1928− fromJSONKey = FromJSONKeyTextParser $
1929− maybe (fail "invalid UUID") pure . UUID.fromText
1930−
19311489-------------------------------------------------------------------------------
19321490-- vector
19331491-------------------------------------------------------------------------------
19341492
19351493instance FromJSON1 Vector where
1936− liftParseJSON p _ = withArray "Vector" $
1494+ liftParseJSON p _ = withArray "Vector a" $
19371495 V.mapM (uncurry $ parseIndexedJSON p) . V.indexed
19381496 {-# INLINE liftParseJSON #-}
19391497
@@ -1947,14 +1505,14 @@ vectorParseJSON s = withArray s $ fmap V.convert . V.mapM (uncurry $ parseIndexe
19471505{-# INLINE vectorParseJSON #-}
19481506
19491507instance (Storable a, FromJSON a) => FromJSON (VS.Vector a) where
1950− parseJSON = vectorParseJSON "Data.Vector.Storable.Vector"
1508+ parseJSON = vectorParseJSON "Data.Vector.Storable.Vector a"
19511509
19521510instance (VP.Prim a, FromJSON a) => FromJSON (VP.Vector a) where
1953− parseJSON = vectorParseJSON "Data.Vector.Primitive.Vector"
1511+ parseJSON = vectorParseJSON "Data.Vector.Primitive.Vector a"
19541512 {-# INLINE parseJSON #-}
19551513
19561514instance (VG.Vector VU.Vector a, FromJSON a) => FromJSON (VU.Vector a) where
1957− parseJSON = vectorParseJSON "Data.Vector.Unboxed.Vector"
1515+ parseJSON = vectorParseJSON "Data.Vector.Unboxed.Vector a"
19581516 {-# INLINE parseJSON #-}
19591517
19601518-------------------------------------------------------------------------------
@@ -1968,15 +1526,15 @@ instance (Eq a, Hashable a, FromJSON a) => FromJSON (HashSet.HashSet a) where
19681526
19691527instance (FromJSONKey k, Eq k, Hashable k) => FromJSON1 (H.HashMap k) where
19701528 liftParseJSON p _ = case fromJSONKey of
1971− FromJSONKeyCoerce _ -> withObject "HashMap ~Text" $
1529+ FromJSONKeyCoerce _ -> withObject "HashMap ~Text v" $
19721530 uc . H.traverseWithKey (\k v -> p v <?> Key k)
1973− FromJSONKeyText f -> withObject "HashMap" $
1531+ FromJSONKeyText f -> withObject "HashMap k v" $
19741532 fmap (mapKey f) . H.traverseWithKey (\k v -> p v <?> Key k)
1975− FromJSONKeyTextParser f -> withObject "HashMap" $
1533+ FromJSONKeyTextParser f -> withObject "HashMap k v" $
19761534 H.foldrWithKey (\k v m -> H.insert <$> f k <?> Key k <*> p v <?> Key k <*> m) (pure H.empty)
1977− FromJSONKeyValue f -> withArray "Map" $ \arr ->
1978− fmap H.fromList . Tr.sequence .
1979− zipWith (parseIndexedJSONPair f p) [0..] . V.toList $ arr
1535+ FromJSONKeyValue f -> withArray "Map k v" $ \arr ->
1536+ H.fromList <$> (Tr.sequence .
1537+ zipWith (parseIndexedJSONPair f p) [0..] . V.toList $ arr)
19801538 where
19811539 uc :: Parser (H.HashMap Text v) -> Parser (H.HashMap k v)
19821540 uc = unsafeCoerce
@@ -1997,33 +1555,11 @@ instance FromJSON DotNetTime where
19971555 parseJSON = withText "DotNetTime" $ \t ->
19981556 let (s,m) = T.splitAt (T.length t - 5) t
19991557 t' = T.concat [s,".",m]
2000− in case parseTimeM True defaultTimeLocale "/Date(%s%Q)/" (unpack t') of
1558+ in case parseTime defaultTimeLocale "/Date(%s%Q)/" (unpack t') of
20011559 Just d -> pure (DotNetTime d)
20021560 _ -> fail "could not parse .NET time"
20031561 {-# INLINE parseJSON #-}
20041562
2005−-------------------------------------------------------------------------------
2006−-- primitive
2007−-------------------------------------------------------------------------------
2008−
2009−instance FromJSON a => FromJSON (PM.Array a) where
2010− -- note: we could do better than this if vector exposed the data
2011− -- constructor in Data.Vector.
2012− parseJSON = fmap Exts.fromList . parseJSON
2013−
2014−instance FromJSON a => FromJSON (PM.SmallArray a) where
2015− parseJSON = fmap Exts.fromList . parseJSON
2016−
2017−#if MIN_VERSION_primitive(0,6,4)
2018−instance (PM.Prim a,FromJSON a) => FromJSON (PM.PrimArray a) where
2019− parseJSON = fmap Exts.fromList . parseJSON
2020−
2021−#if !MIN_VERSION_primitive(0,7,0)
2022−instance (PM.PrimUnlifted a,FromJSON a) => FromJSON (PM.UnliftedArray a) where
2023− parseJSON = fmap Exts.fromList . parseJSON
2024−#endif
2025−#endif
2026−
20271563-------------------------------------------------------------------------------
20281564-- time
20291565-------------------------------------------------------------------------------
@@ -2049,17 +1585,6 @@ instance FromJSONKey LocalTime where
20491585 fromJSONKey = FromJSONKeyTextParser (Time.run Time.localTime)
20501586
20511587
2052−-- | Supported string formats:
2053−--
2054−-- @YYYY-MM-DD HH:MM Z@
2055−-- @YYYY-MM-DD HH:MM:SS Z@
2056−-- @YYYY-MM-DD HH:MM:SS.SSS Z@
2057−--
2058−-- The first space may instead be a @T@, and the second space is
2059−-- optional. The @Z@ represents UTC. The @Z@ may be replaced with a
2060−-- time zone offset of the form @+0000@ or @-08:00@, where the first
2061−-- two digits are hours, the @:@ is optional and the second two digits
2062−-- (also optional) are minutes.
20631588instance FromJSON ZonedTime where
20641589 parseJSON = withText "ZonedTime" (Time.run Time.zonedTime)
20651590
@@ -2074,57 +1599,14 @@ instance FromJSONKey UTCTime where
20741599 fromJSONKey = FromJSONKeyTextParser (Time.run Time.utcTime)
20751600
20761601
2077−-- | This instance includes a bounds check to prevent maliciously
2078−-- large inputs to fill up the memory of the target system. You can
2079−-- newtype 'Scientific' and provide your own instance using
2080−-- 'withScientific' if you want to allow larger inputs.
1602+-- | /WARNING:/ Only parse lengths of time from trusted input
1603+-- since an attacker could easily fill up the memory of the target
1604+-- system by specifying a scientific number with a big exponent like
1605+-- @1e1000000000@.
20811606instance FromJSON NominalDiffTime where
2082− parseJSON = withBoundedScientific "NominalDiffTime" $ pure . realToFrac
2083− {-# INLINE parseJSON #-}
2084−
2085−
2086−-- | This instance includes a bounds check to prevent maliciously
2087−-- large inputs to fill up the memory of the target system. You can
2088−-- newtype 'Scientific' and provide your own instance using
2089−-- 'withScientific' if you want to allow larger inputs.
2090−instance FromJSON DiffTime where
2091− parseJSON = withBoundedScientific "DiffTime" $ pure . realToFrac
1607+ parseJSON = withScientific "NominalDiffTime" $ pure . realToFrac
20921608 {-# INLINE parseJSON #-}
20931609
2094−instance FromJSON SystemTime where
2095− parseJSON v = prependContext "SystemTime" $ do
2096− n <- parseJSON v
2097− let n' = floor (n * fromInteger (resolution n) :: Nano)
2098− let (secs, nano) = n' `divMod` resolution n
2099− return (MkSystemTime (fromInteger secs) (fromInteger nano))
2100−
2101−instance FromJSON CalendarDiffTime where
2102− parseJSON = withObject "CalendarDiffTime" $ \obj -> CalendarDiffTime
2103− <$> obj .: "months"
2104− <*> obj .: "time"
2105−
2106−instance FromJSON CalendarDiffDays where
2107− parseJSON = withObject "CalendarDiffDays" $ \obj -> CalendarDiffDays
2108− <$> obj .: "months"
2109− <*> obj .: "days"
2110−
2111−instance FromJSON DayOfWeek where
2112− parseJSON = withText "DaysOfWeek" parseDayOfWeek
2113−
2114−parseDayOfWeek :: T.Text -> Parser DayOfWeek
2115−parseDayOfWeek t = case T.toLower t of
2116− "monday" -> return Monday
2117− "tuesday" -> return Tuesday
2118− "wednesday" -> return Wednesday
2119− "thursday" -> return Thursday
2120− "friday" -> return Friday
2121− "saturday" -> return Saturday
2122− "sunday" -> return Sunday
2123− _ -> fail "Invalid week day"
2124−
2125−instance FromJSONKey DayOfWeek where
2126− fromJSONKey = FromJSONKeyTextParser parseDayOfWeek
2127−
21281610-------------------------------------------------------------------------------
21291611-- base Monoid/Semigroup
21301612-------------------------------------------------------------------------------
@@ -2245,15 +1727,14 @@ instance FromJSON a => FromJSON (Semigroup.Option a) where
22451727
22461728instance FromJSON1 Proxy where
22471729 {-# INLINE liftParseJSON #-}
2248− liftParseJSON _ _ = fromNull "Proxy" Proxy
1730+ liftParseJSON _ _ Null = pure Proxy
1731+ liftParseJSON _ _ v = typeMismatch "Proxy" v
22491732
22501733instance FromJSON (Proxy a) where
22511734 {-# INLINE parseJSON #-}
2252− parseJSON = fromNull "Proxy" Proxy
1735+ parseJSON Null = pure Proxy
1736+ parseJSON v = typeMismatch "Proxy" v
22531737
2254−fromNull :: String -> a -> Value -> Parser a
2255−fromNull _ a Null = pure a
2256−fromNull c _ v = prependContext c (typeMismatch "Null" v)
22571738
22581739instance FromJSON2 Tagged where
22591740 liftParseJSON2 _ _ p _ = fmap Tagged . p
@@ -2280,7 +1761,10 @@ instance (FromJSON a, FromJSON b, FromJSON c) => FromJSONKey (a,b,c)
22801761instance (FromJSON a, FromJSON b, FromJSON c, FromJSON d) => FromJSONKey (a,b,c,d)
22811762
22821763instance FromJSONKey Char where
2283− fromJSONKey = FromJSONKeyTextParser parseChar
1764+ fromJSONKey = FromJSONKeyTextParser $ \t ->
1765+ if T.length t == 1
1766+ then return (T.index t 0)
1767+ else typeMismatch "Expected Char but String didn't contain exactly one character" (String t)
22841768 fromJSONKeyList = FromJSONKeyText T.unpack
22851769
22861770instance (FromJSONKey a, FromJSON a) => FromJSONKey [a] where