yaml-0.8.18.7: Support for parsing and rendering YAML documents.

Safe HaskellNone
LanguageHaskell98

Data.Yaml

Contents

Description

Provides a high-level interface for processing YAML files.

This module reuses most of the infrastructure from the aeson package. This means that you can use all of the existing tools for JSON processing for processing YAML files. As a result, much of the documentation below mentions JSON; do not let that confuse you, it's intentional.

For the most part, YAML content translates directly into JSON, and therefore there is very little data loss. If you need to deal with YAML more directly (e.g., directly deal with aliases), you should use the Text.Libyaml module instead.

For documentation on the aeson types, functions, classes, and operators, please see the Data.Aeson module of the aeson package.

Look in the examples directory of the source repository for some initial pointers on how to use this library.

Synopsis

Types

data Value :: * #

A JSON value represented as a Haskell value.

Instances

Eq Value 

Methods

(==) :: Value -> Value -> Bool #

(/=) :: Value -> Value -> Bool #

Data Value 

Methods

gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> Value -> c Value #

gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c Value #

toConstr :: Value -> Constr #

dataTypeOf :: Value -> DataType #

dataCast1 :: Typeable (* -> *) t => (forall d. Data d => c (t d)) -> Maybe (c Value) #

dataCast2 :: Typeable (* -> * -> *) t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c Value) #

gmapT :: (forall b. Data b => b -> b) -> Value -> Value #

gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Value -> r #

gmapQr :: (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Value -> r #

gmapQ :: (forall d. Data d => d -> u) -> Value -> [u] #

gmapQi :: Int -> (forall d. Data d => d -> u) -> Value -> u #

gmapM :: Monad m => (forall d. Data d => d -> m d) -> Value -> m Value #

gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> Value -> m Value #

gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> Value -> m Value #

Read Value 
Show Value 

Methods

showsPrec :: Int -> Value -> ShowS #

show :: Value -> String #

showList :: [Value] -> ShowS #

IsString Value 

Methods

fromString :: String -> Value #

Lift Value 

Methods

lift :: Value -> Q Exp #

Hashable Value 

Methods

hashWithSalt :: Int -> Value -> Int #

hash :: Value -> Int #

FromJSON Value 
ToJSON Value 
KeyValue Pair 

Methods

(.=) :: ToJSON v => Text -> v -> Pair #

NFData Value 

Methods

rnf :: Value -> () #

data Parser a :: * -> * #

A JSON parser.

Instances

Monad Parser 

Methods

(>>=) :: Parser a -> (a -> Parser b) -> Parser b #

(>>) :: Parser a -> Parser b -> Parser b #

return :: a -> Parser a #

fail :: String -> Parser a #

Functor Parser 

Methods

fmap :: (a -> b) -> Parser a -> Parser b #

(<$) :: a -> Parser b -> Parser a #

MonadFail Parser 

Methods

fail :: String -> Parser a #

Applicative Parser 

Methods

pure :: a -> Parser a #

(<*>) :: Parser (a -> b) -> Parser a -> Parser b #

(*>) :: Parser a -> Parser b -> Parser b #

(<*) :: Parser a -> Parser b -> Parser a #

Alternative Parser 

Methods

empty :: Parser a #

(<|>) :: Parser a -> Parser a -> Parser a #

some :: Parser a -> Parser [a] #

many :: Parser a -> Parser [a] #

MonadPlus Parser 

Methods

mzero :: Parser a #

mplus :: Parser a -> Parser a -> Parser a #

Semigroup (Parser a) 

Methods

(<>) :: Parser a -> Parser a -> Parser a #

sconcat :: NonEmpty (Parser a) -> Parser a #

stimes :: Integral b => b -> Parser a -> Parser a #

Monoid (Parser a) 

Methods

mempty :: Parser a #

mappend :: Parser a -> Parser a -> Parser a #

mconcat :: [Parser a] -> Parser a #

type Object = HashMap Text Value #

A JSON "object" (key/value map).

type Array = Vector Value #

A JSON "array" (sequence).

prettyPrintParseException :: ParseException -> String Source #

Alternative to show to display a ParseException on the screen. Instead of displaying the data constructors applied to their arguments, a more textual output is returned. For example, instead of printing:

InvalidYaml (Just (YamlParseException {yamlProblem = "did not find expected ',' or '}'", yamlContext = "while parsing a flow mapping", yamlProblemMark = YamlMark {yamlIndex = 42, yamlLine = 2, yamlColumn = 12}})))

It looks more pleasant to print:

YAML parse exception at line 2, column 12,
while parsing a flow mapping:
did not find expected ',' or '}'

Since 0.8.11

data YamlMark Source #

The pointer position

Constructors

YamlMark 

Fields

Constructors and accessors

object :: [Pair] -> Value #

Create a Value from a list of name/value Pairs. If duplicate keys arise, earlier keys and their associated values win.

(.=) :: KeyValue kv => forall v. ToJSON v => Text -> v -> kv #

(.:) :: FromJSON a => Object -> Text -> Parser a #

Retrieve the value associated with the given key of an Object. The result is empty if the key is not present or the value cannot be converted to the desired type.

This accessor is appropriate if the key and value must be present in an object for it to be valid. If the key and value are optional, use .:? instead.

(.:?) :: FromJSON a => Object -> Text -> Parser (Maybe a) #

Retrieve the value associated with the given key of an Object. The result is Nothing if the key is not present or if its value is Null, or empty if the value cannot be converted to the desired type.

This accessor is most useful if the key and value can be absent from an object without affecting its validity. If the key and value are mandatory, use .: instead.

(.!=) :: Parser (Maybe a) -> a -> Parser a #

Helper for use in combination with .:? to provide default values for optional JSON object fields.

This combinator is most useful if the key and value can be absent from an object without affecting its validity and we know a default value to assign in that case. If the key and value are mandatory, use .: instead.

Example usage:

 v1 <- o .:? "opt_field_with_dfl" .!= "default_val"
 v2 <- o .:  "mandatory_field"
 v3 <- o .:? "opt_field2"

Parsing

parseMonad :: Monad m => (a -> Parser b) -> a -> m b Source #

parseEither :: (a -> Parser b) -> a -> Either String b #

Run a Parser with an Either result type. If the parse fails, the Left payload will contain an error message.

parseMaybe :: (a -> Parser b) -> a -> Maybe b #

Run a Parser with a Maybe result type.

Classes

class ToJSON a where #

A type that can be converted to JSON.

An example type and instance:

-- Allow ourselves to write Text literals.
{-# LANGUAGE OverloadedStrings #-}

data Coord = Coord { x :: Double, y :: Double }

instance ToJSON Coord where
  toJSON (Coord x y) = object ["x" .= x, "y" .= y]

  toEncoding (Coord x y) = pairs ("x" .= x <> "y" .= y)

Instead of manually writing your ToJSON instance, there are two options to do it automatically:

  • Data.Aeson.TH provides Template Haskell functions which will derive an instance at compile time. The generated instance is optimized for your type so will probably be more efficient than the following two options:
  • The compiler can provide a default generic implementation for toJSON.

To use the second, simply add a deriving Generic clause to your datatype and declare a ToJSON instance for your datatype without giving definitions for toJSON or toEncoding.

For example, the previous example can be simplified to a more minimal instance:

{-# LANGUAGE DeriveGeneric #-}

import GHC.Generics

data Coord = Coord { x :: Double, y :: Double } deriving Generic

instance ToJSON Coord where
    toEncoding = genericToEncoding defaultOptions

Why do we provide an implementation for toEncoding here? The toEncoding function is a relatively new addition to this class. To allow users of older versions of this library to upgrade without having to edit all of their instances or encounter surprising incompatibilities, the default implementation of toEncoding uses toJSON. This produces correct results, but since it performs an intermediate conversion to a Value, it will be less efficient than directly emitting an Encoding. Our one-liner definition of toEncoding above bypasses the intermediate Value.

If DefaultSignatures doesn't give exactly the results you want, you can customize the generic encoding with only a tiny amount of effort, using genericToJSON and genericToEncoding with your preferred Options:

instance ToJSON Coord where
    toJSON     = genericToJSON defaultOptions
    toEncoding = genericToEncoding defaultOptions

Minimal complete definition

Nothing

Instances

ToJSON Bool 
ToJSON Char 
ToJSON Double 
ToJSON Float 
ToJSON Int 
ToJSON Int8 
ToJSON Int16 
ToJSON Int32 
ToJSON Int64 
ToJSON Integer 
ToJSON Ordering 
ToJSON Word 
ToJSON Word8 
ToJSON Word16 
ToJSON Word32 
ToJSON Word64 
ToJSON () 

Methods

toJSON :: () -> Value #

toEncoding :: () -> Encoding #

toJSONList :: [()] -> Value #

toEncodingList :: [()] -> Encoding #

ToJSON Scientific 
ToJSON Number 
ToJSON Text 
ToJSON UTCTime 
ToJSON Value 
ToJSON DotNetTime 
ToJSON Text 
ToJSON Natural 
ToJSON Version 
ToJSON IntSet 
ToJSON LocalTime 
ToJSON ZonedTime 
ToJSON TimeOfDay 
ToJSON NominalDiffTime 
ToJSON Day 
ToJSON a => ToJSON [a] 

Methods

toJSON :: [a] -> Value #

toEncoding :: [a] -> Encoding #

toJSONList :: [[a]] -> Value #

toEncodingList :: [[a]] -> Encoding #

ToJSON a => ToJSON (Maybe a) 
(ToJSON a, Integral a) => ToJSON (Ratio a) 
ToJSON a => ToJSON (Identity a) 
ToJSON a => ToJSON (Min a) 

Methods

toJSON :: Min a -> Value #

toEncoding :: Min a -> Encoding #

toJSONList :: [Min a] -> Value #

toEncodingList :: [Min a] -> Encoding #

ToJSON a => ToJSON (Max a) 

Methods

toJSON :: Max a -> Value #

toEncoding :: Max a -> Encoding #

toJSONList :: [Max a] -> Value #

toEncodingList :: [Max a] -> Encoding #

ToJSON a => ToJSON (First a) 
ToJSON a => ToJSON (Last a) 
ToJSON a => ToJSON (WrappedMonoid a) 
ToJSON a => ToJSON (Option a) 
ToJSON a => ToJSON (NonEmpty a) 
HasResolution a => ToJSON (Fixed a) 
ToJSON a => ToJSON (Dual a) 
ToJSON a => ToJSON (First a) 
ToJSON a => ToJSON (Last a) 
ToJSON v => ToJSON (Tree v) 
ToJSON a => ToJSON (Seq a) 

Methods

toJSON :: Seq a -> Value #

toEncoding :: Seq a -> Encoding #

toJSONList :: [Seq a] -> Value #

toEncodingList :: [Seq a] -> Encoding #

ToJSON a => ToJSON (IntMap a) 
ToJSON a => ToJSON (Set a) 

Methods

toJSON :: Set a -> Value #

toEncoding :: Set a -> Encoding #

toJSONList :: [Set a] -> Value #

toEncodingList :: [Set a] -> Encoding #

ToJSON a => ToJSON (DList a) 
ToJSON a => ToJSON (HashSet a) 
ToJSON a => ToJSON (Vector a) 
(Vector Vector a, ToJSON a) => ToJSON (Vector a) 
(Storable a, ToJSON a) => ToJSON (Vector a) 
(Prim a, ToJSON a) => ToJSON (Vector a) 
(ToJSON a, ToJSON b) => ToJSON (Either a b) 

Methods

toJSON :: Either a b -> Value #

toEncoding :: Either a b -> Encoding #

toJSONList :: [Either a b] -> Value #

toEncodingList :: [Either a b] -> Encoding #

(ToJSON a, ToJSON b) => ToJSON (a, b) 

Methods

toJSON :: (a, b) -> Value #

toEncoding :: (a, b) -> Encoding #

toJSONList :: [(a, b)] -> Value #

toEncodingList :: [(a, b)] -> Encoding #

(ToJSON v, ToJSONKey k) => ToJSON (HashMap k v) 
(ToJSON v, ToJSONKey k) => ToJSON (Map k v) 

Methods

toJSON :: Map k v -> Value #

toEncoding :: Map k v -> Encoding #

toJSONList :: [Map k v] -> Value #

toEncodingList :: [Map k v] -> Encoding #

ToJSON (Proxy k a) 

Methods

toJSON :: Proxy k a -> Value #

toEncoding :: Proxy k a -> Encoding #

toJSONList :: [Proxy k a] -> Value #

toEncodingList :: [Proxy k a] -> Encoding #

(ToJSON a, ToJSON b, ToJSON c) => ToJSON (a, b, c) 

Methods

toJSON :: (a, b, c) -> Value #

toEncoding :: (a, b, c) -> Encoding #

toJSONList :: [(a, b, c)] -> Value #

toEncodingList :: [(a, b, c)] -> Encoding #

ToJSON a => ToJSON (Const k a b) 

Methods

toJSON :: Const k a b -> Value #

toEncoding :: Const k a b -> Encoding #

toJSONList :: [Const k a b] -> Value #

toEncodingList :: [Const k a b] -> Encoding #

ToJSON b => ToJSON (Tagged k a b) 

Methods

toJSON :: Tagged k a b -> Value #

toEncoding :: Tagged k a b -> Encoding #

toJSONList :: [Tagged k a b] -> Value #

toEncodingList :: [Tagged k a b] -> Encoding #

(ToJSON a, ToJSON b, ToJSON c, ToJSON d) => ToJSON (a, b, c, d) 

Methods

toJSON :: (a, b, c, d) -> Value #

toEncoding :: (a, b, c, d) -> Encoding #

toJSONList :: [(a, b, c, d)] -> Value #

toEncodingList :: [(a, b, c, d)] -> Encoding #

(ToJSON1 f, ToJSON1 g, ToJSON a) => ToJSON (Sum * f g a) 

Methods

toJSON :: Sum * f g a -> Value #

toEncoding :: Sum * f g a -> Encoding #

toJSONList :: [Sum * f g a] -> Value #

toEncodingList :: [Sum * f g a] -> Encoding #

(ToJSON1 f, ToJSON1 g, ToJSON a) => ToJSON (Product * f g a) 

Methods

toJSON :: Product * f g a -> Value #

toEncoding :: Product * f g a -> Encoding #

toJSONList :: [Product * f g a] -> Value #

toEncodingList :: [Product * f g a] -> Encoding #

(ToJSON a, ToJSON b, ToJSON c, ToJSON d, ToJSON e) => ToJSON (a, b, c, d, e) 

Methods

toJSON :: (a, b, c, d, e) -> Value #

toEncoding :: (a, b, c, d, e) -> Encoding #

toJSONList :: [(a, b, c, d, e)] -> Value #

toEncodingList :: [(a, b, c, d, e)] -> Encoding #

(ToJSON1 f, ToJSON1 g, ToJSON a) => ToJSON (Compose * * f g a) 

Methods

toJSON :: Compose * * f g a -> Value #

toEncoding :: Compose * * f g a -> Encoding #

toJSONList :: [Compose * * f g a] -> Value #

toEncodingList :: [Compose * * f g a] -> Encoding #

(ToJSON a, ToJSON b, ToJSON c, ToJSON d, ToJSON e, ToJSON f) => ToJSON (a, b, c, d, e, f) 

Methods

toJSON :: (a, b, c, d, e, f) -> Value #

toEncoding :: (a, b, c, d, e, f) -> Encoding #

toJSONList :: [(a, b, c, d, e, f)] -> Value #

toEncodingList :: [(a, b, c, d, e, f)] -> Encoding #

(ToJSON a, ToJSON b, ToJSON c, ToJSON d, ToJSON e, ToJSON f, ToJSON g) => ToJSON (a, b, c, d, e, f, g) 

Methods

toJSON :: (a, b, c, d, e, f, g) -> Value #

toEncoding :: (a, b, c, d, e, f, g) -> Encoding #

toJSONList :: [(a, b, c, d, e, f, g)] -> Value #

toEncodingList :: [(a, b, c, d, e, f, g)] -> Encoding #

(ToJSON a, ToJSON b, ToJSON c, ToJSON d, ToJSON e, ToJSON f, ToJSON g, ToJSON h) => ToJSON (a, b, c, d, e, f, g, h) 

Methods

toJSON :: (a, b, c, d, e, f, g, h) -> Value #

toEncoding :: (a, b, c, d, e, f, g, h) -> Encoding #

toJSONList :: [(a, b, c, d, e, f, g, h)] -> Value #

toEncodingList :: [(a, b, c, d, e, f, g, h)] -> Encoding #

(ToJSON a, ToJSON b, ToJSON c, ToJSON d, ToJSON e, ToJSON f, ToJSON g, ToJSON h, ToJSON i) => ToJSON (a, b, c, d, e, f, g, h, i) 

Methods

toJSON :: (a, b, c, d, e, f, g, h, i) -> Value #

toEncoding :: (a, b, c, d, e, f, g, h, i) -> Encoding #

toJSONList :: [(a, b, c, d, e, f, g, h, i)] -> Value #

toEncodingList :: [(a, b, c, d, e, f, g, h, i)] -> Encoding #

(ToJSON a, ToJSON b, ToJSON c, ToJSON d, ToJSON e, ToJSON f, ToJSON g, ToJSON h, ToJSON i, ToJSON j) => ToJSON (a, b, c, d, e, f, g, h, i, j) 

Methods

toJSON :: (a, b, c, d, e, f, g, h, i, j) -> Value #

toEncoding :: (a, b, c, d, e, f, g, h, i, j) -> Encoding #

toJSONList :: [(a, b, c, d, e, f, g, h, i, j)] -> Value #

toEncodingList :: [(a, b, c, d, e, f, g, h, i, j)] -> Encoding #

(ToJSON a, ToJSON b, ToJSON c, ToJSON d, ToJSON e, ToJSON f, ToJSON g, ToJSON h, ToJSON i, ToJSON j, ToJSON k) => ToJSON (a, b, c, d, e, f, g, h, i, j, k) 

Methods

toJSON :: (a, b, c, d, e, f, g, h, i, j, k) -> Value #

toEncoding :: (a, b, c, d, e, f, g, h, i, j, k) -> Encoding #

toJSONList :: [(a, b, c, d, e, f, g, h, i, j, k)] -> Value #

toEncodingList :: [(a, b, c, d, e, f, g, h, i, j, k)] -> Encoding #

(ToJSON a, ToJSON b, ToJSON c, ToJSON d, ToJSON e, ToJSON f, ToJSON g, ToJSON h, ToJSON i, ToJSON j, ToJSON k, ToJSON l) => ToJSON (a, b, c, d, e, f, g, h, i, j, k, l) 

Methods

toJSON :: (a, b, c, d, e, f, g, h, i, j, k, l) -> Value #

toEncoding :: (a, b, c, d, e, f, g, h, i, j, k, l) -> Encoding #

toJSONList :: [(a, b, c, d, e, f, g, h, i, j, k, l)] -> Value #

toEncodingList :: [(a, b, c, d, e, f, g, h, i, j, k, l)] -> Encoding #

(ToJSON a, ToJSON b, ToJSON c, ToJSON d, ToJSON e, ToJSON f, ToJSON g, ToJSON h, ToJSON i, ToJSON j, ToJSON k, ToJSON l, ToJSON m) => ToJSON (a, b, c, d, e, f, g, h, i, j, k, l, m) 

Methods

toJSON :: (a, b, c, d, e, f, g, h, i, j, k, l, m) -> Value #

toEncoding :: (a, b, c, d, e, f, g, h, i, j, k, l, m) -> Encoding #

toJSONList :: [(a, b, c, d, e, f, g, h, i, j, k, l, m)] -> Value #

toEncodingList :: [(a, b, c, d, e, f, g, h, i, j, k, l, m)] -> Encoding #

(ToJSON a, ToJSON b, ToJSON c, ToJSON d, ToJSON e, ToJSON f, ToJSON g, ToJSON h, ToJSON i, ToJSON j, ToJSON k, ToJSON l, ToJSON m, ToJSON n) => ToJSON (a, b, c, d, e, f, g, h, i, j, k, l, m, n) 

Methods

toJSON :: (a, b, c, d, e, f, g, h, i, j, k, l, m, n) -> Value #

toEncoding :: (a, b, c, d, e, f, g, h, i, j, k, l, m, n) -> Encoding #

toJSONList :: [(a, b, c, d, e, f, g, h, i, j, k, l, m, n)] -> Value #

toEncodingList :: [(a, b, c, d, e, f, g, h, i, j, k, l, m, n)] -> Encoding #

(ToJSON a, ToJSON b, ToJSON c, ToJSON d, ToJSON e, ToJSON f, ToJSON g, ToJSON h, ToJSON i, ToJSON j, ToJSON k, ToJSON l, ToJSON m, ToJSON n, ToJSON o) => ToJSON (a, b, c, d, e, f, g, h, i, j, k, l, m, n, o) 

Methods

toJSON :: (a, b, c, d, e, f, g, h, i, j, k, l, m, n, o) -> Value #

toEncoding :: (a, b, c, d, e, f, g, h, i, j, k, l, m, n, o) -> Encoding #

toJSONList :: [(a, b, c, d, e, f, g, h, i, j, k, l, m, n, o)] -> Value #

toEncodingList :: [(a, b, c, d, e, f, g, h, i, j, k, l, m, n, o)] -> Encoding #

class FromJSON a where #

A type that can be converted from JSON, with the possibility of failure.

In many cases, you can get the compiler to generate parsing code for you (see below). To begin, let's cover writing an instance by hand.

There are various reasons a conversion could fail. For example, an Object could be missing a required key, an Array could be of the wrong size, or a value could be of an incompatible type.

The basic ways to signal a failed conversion are as follows:

  • empty and mzero work, but are terse and uninformative
  • fail yields a custom error message
  • typeMismatch produces an informative message for cases when the value encountered is not of the expected type

An example type and instance:

-- Allow ourselves to write Text literals.
{-# LANGUAGE OverloadedStrings #-}

data Coord = Coord { x :: Double, y :: Double }

instance FromJSON Coord where
  parseJSON (Object v) = Coord    <$>
                         v .: "x" <*>
                         v .: "y"

  -- We do not expect a non-Object value here.
  -- We could use mzero to fail, but typeMismatch
  -- gives a much more informative error message.
  parseJSON invalid    = typeMismatch "Coord" invalid

Instead of manually writing your FromJSON instance, there are two options to do it automatically:

  • Data.Aeson.TH provides Template Haskell functions which will derive an instance at compile time. The generated instance is optimized for your type so will probably be more efficient than the following two options:
  • The compiler can provide a default generic implementation for parseJSON.

To use the second, simply add a deriving Generic clause to your datatype and declare a FromJSON instance for your datatype without giving a definition for parseJSON.

For example, the previous example can be simplified to just:

{-# LANGUAGE DeriveGeneric #-}

import GHC.Generics

data Coord = Coord { x :: Double, y :: Double } deriving Generic

instance FromJSON Coord

If DefaultSignatures doesn't give exactly the results you want, you can customize the generic decoding with only a tiny amount of effort, using genericParseJSON with your preferred Options:

instance FromJSON Coord where
    parseJSON = genericParseJSON defaultOptions

Minimal complete definition

Nothing

Instances

FromJSON Bool 
FromJSON Char 
FromJSON Double 
FromJSON Float 
FromJSON Int 
FromJSON Int8 
FromJSON Int16 
FromJSON Int32 
FromJSON Int64 
FromJSON Integer

WARNING: Only parse Integers from trusted input since an attacker could easily fill up the memory of the target system by specifying a scientific number with a big exponent like 1e1000000000.

FromJSON Ordering 
FromJSON Word 
FromJSON Word8 
FromJSON Word16 
FromJSON Word32 
FromJSON Word64 
FromJSON () 

Methods

parseJSON :: Value -> Parser () #

parseJSONList :: Value -> Parser [()] #

FromJSON Scientific 
FromJSON Number 
FromJSON Text 
FromJSON UTCTime 
FromJSON Value 
FromJSON DotNetTime 
FromJSON Text 
FromJSON Natural 
FromJSON Version 
FromJSON IntSet 
FromJSON LocalTime 
FromJSON ZonedTime 
FromJSON TimeOfDay 
FromJSON NominalDiffTime

WARNING: Only parse lengths of time from trusted input since an attacker could easily fill up the memory of the target system by specifying a scientific number with a big exponent like 1e1000000000.

FromJSON Day 
FromJSON a => FromJSON [a] 

Methods

parseJSON :: Value -> Parser [a] #

parseJSONList :: Value -> Parser [[a]] #

FromJSON a => FromJSON (Maybe a) 
(FromJSON a, Integral a) => FromJSON (Ratio a) 
FromJSON a => FromJSON (Identity a) 
FromJSON a => FromJSON (Min a) 

Methods

parseJSON :: Value -> Parser (Min a) #

parseJSONList :: Value -> Parser [Min a] #

FromJSON a => FromJSON (Max a) 

Methods

parseJSON :: Value -> Parser (Max a) #

parseJSONList :: Value -> Parser [Max a] #

FromJSON a => FromJSON (First a) 
FromJSON a => FromJSON (Last a) 
FromJSON a => FromJSON (WrappedMonoid a) 
FromJSON a => FromJSON (Option a) 
FromJSON a => FromJSON (NonEmpty a) 
HasResolution a => FromJSON (Fixed a)

WARNING: Only parse fixed-precision numbers from trusted input since an attacker could easily fill up the memory of the target system by specifying a scientific number with a big exponent like 1e1000000000.

FromJSON a => FromJSON (Dual a) 
FromJSON a => FromJSON (First a) 
FromJSON a => FromJSON (Last a) 
FromJSON v => FromJSON (Tree v) 
FromJSON a => FromJSON (Seq a) 

Methods

parseJSON :: Value -> Parser (Seq a) #

parseJSONList :: Value -> Parser [Seq a] #

FromJSON a => FromJSON (IntMap a) 
(Ord a, FromJSON a) => FromJSON (Set a) 

Methods

parseJSON :: Value -> Parser (Set a) #

parseJSONList :: Value -> Parser [Set a] #

FromJSON a => FromJSON (DList a) 
(Eq a, Hashable a, FromJSON a) => FromJSON (HashSet a) 
FromJSON a => FromJSON (Vector a) 
(Vector Vector a, FromJSON a) => FromJSON (Vector a) 
(Storable a, FromJSON a) => FromJSON (Vector a) 
(Prim a, FromJSON a) => FromJSON (Vector a) 
(FromJSON a, FromJSON b) => FromJSON (Either a b) 

Methods

parseJSON :: Value -> Parser (Either a b) #

parseJSONList :: Value -> Parser [Either a b] #

(FromJSON a, FromJSON b) => FromJSON (a, b) 

Methods

parseJSON :: Value -> Parser (a, b) #

parseJSONList :: Value -> Parser [(a, b)] #

(FromJSON v, FromJSONKey k, Eq k, Hashable k) => FromJSON (HashMap k v) 
(FromJSONKey k, Ord k, FromJSON v) => FromJSON (Map k v) 

Methods

parseJSON :: Value -> Parser (Map k v) #

parseJSONList :: Value -> Parser [Map k v] #

FromJSON (Proxy k a) 

Methods

parseJSON :: Value -> Parser (Proxy k a) #

parseJSONList :: Value -> Parser [Proxy k a] #

(FromJSON a, FromJSON b, FromJSON c) => FromJSON (a, b, c) 

Methods

parseJSON :: Value -> Parser (a, b, c) #

parseJSONList :: Value -> Parser [(a, b, c)] #

FromJSON a => FromJSON (Const k a b) 

Methods

parseJSON :: Value -> Parser (Const k a b) #

parseJSONList :: Value -> Parser [Const k a b] #

FromJSON b => FromJSON (Tagged k a b) 

Methods

parseJSON :: Value -> Parser (Tagged k a b) #

parseJSONList :: Value -> Parser [Tagged k a b] #

(FromJSON a, FromJSON b, FromJSON c, FromJSON d) => FromJSON (a, b, c, d) 

Methods

parseJSON :: Value -> Parser (a, b, c, d) #

parseJSONList :: Value -> Parser [(a, b, c, d)] #

(FromJSON1 f, FromJSON1 g, FromJSON a) => FromJSON (Sum * f g a) 

Methods

parseJSON :: Value -> Parser (Sum * f g a) #

parseJSONList :: Value -> Parser [Sum * f g a] #

(FromJSON1 f, FromJSON1 g, FromJSON a) => FromJSON (Product * f g a) 

Methods

parseJSON :: Value -> Parser (Product * f g a) #

parseJSONList :: Value -> Parser [Product * f g a] #

(FromJSON a, FromJSON b, FromJSON c, FromJSON d, FromJSON e) => FromJSON (a, b, c, d, e) 

Methods

parseJSON :: Value -> Parser (a, b, c, d, e) #

parseJSONList :: Value -> Parser [(a, b, c, d, e)] #

(FromJSON1 f, FromJSON1 g, FromJSON a) => FromJSON (Compose * * f g a) 

Methods

parseJSON :: Value -> Parser (Compose * * f g a) #

parseJSONList :: Value -> Parser [Compose * * f g a] #

(FromJSON a, FromJSON b, FromJSON c, FromJSON d, FromJSON e, FromJSON f) => FromJSON (a, b, c, d, e, f) 

Methods

parseJSON :: Value -> Parser (a, b, c, d, e, f) #

parseJSONList :: Value -> Parser [(a, b, c, d, e, f)] #

(FromJSON a, FromJSON b, FromJSON c, FromJSON d, FromJSON e, FromJSON f, FromJSON g) => FromJSON (a, b, c, d, e, f, g) 

Methods

parseJSON :: Value -> Parser (a, b, c, d, e, f, g) #

parseJSONList :: Value -> Parser [(a, b, c, d, e, f, g)] #

(FromJSON a, FromJSON b, FromJSON c, FromJSON d, FromJSON e, FromJSON f, FromJSON g, FromJSON h) => FromJSON (a, b, c, d, e, f, g, h) 

Methods

parseJSON :: Value -> Parser (a, b, c, d, e, f, g, h) #

parseJSONList :: Value -> Parser [(a, b, c, d, e, f, g, h)] #

(FromJSON a, FromJSON b, FromJSON c, FromJSON d, FromJSON e, FromJSON f, FromJSON g, FromJSON h, FromJSON i) => FromJSON (a, b, c, d, e, f, g, h, i) 

Methods

parseJSON :: Value -> Parser (a, b, c, d, e, f, g, h, i) #

parseJSONList :: Value -> Parser [(a, b, c, d, e, f, g, h, i)] #

(FromJSON a, FromJSON b, FromJSON c, FromJSON d, FromJSON e, FromJSON f, FromJSON g, FromJSON h, FromJSON i, FromJSON j) => FromJSON (a, b, c, d, e, f, g, h, i, j) 

Methods

parseJSON :: Value -> Parser (a, b, c, d, e, f, g, h, i, j) #

parseJSONList :: Value -> Parser [(a, b, c, d, e, f, g, h, i, j)] #

(FromJSON a, FromJSON b, FromJSON c, FromJSON d, FromJSON e, FromJSON f, FromJSON g, FromJSON h, FromJSON i, FromJSON j, FromJSON k) => FromJSON (a, b, c, d, e, f, g, h, i, j, k) 

Methods

parseJSON :: Value -> Parser (a, b, c, d, e, f, g, h, i, j, k) #

parseJSONList :: Value -> Parser [(a, b, c, d, e, f, g, h, i, j, k)] #

(FromJSON a, FromJSON b, FromJSON c, FromJSON d, FromJSON e, FromJSON f, FromJSON g, FromJSON h, FromJSON i, FromJSON j, FromJSON k, FromJSON l) => FromJSON (a, b, c, d, e, f, g, h, i, j, k, l) 

Methods

parseJSON :: Value -> Parser (a, b, c, d, e, f, g, h, i, j, k, l) #

parseJSONList :: Value -> Parser [(a, b, c, d, e, f, g, h, i, j, k, l)] #

(FromJSON a, FromJSON b, FromJSON c, FromJSON d, FromJSON e, FromJSON f, FromJSON g, FromJSON h, FromJSON i, FromJSON j, FromJSON k, FromJSON l, FromJSON m) => FromJSON (a, b, c, d, e, f, g, h, i, j, k, l, m) 

Methods

parseJSON :: Value -> Parser (a, b, c, d, e, f, g, h, i, j, k, l, m) #

parseJSONList :: Value -> Parser [(a, b, c, d, e, f, g, h, i, j, k, l, m)] #

(FromJSON a, FromJSON b, FromJSON c, FromJSON d, FromJSON e, FromJSON f, FromJSON g, FromJSON h, FromJSON i, FromJSON j, FromJSON k, FromJSON l, FromJSON m, FromJSON n) => FromJSON (a, b, c, d, e, f, g, h, i, j, k, l, m, n) 

Methods

parseJSON :: Value -> Parser (a, b, c, d, e, f, g, h, i, j, k, l, m, n) #

parseJSONList :: Value -> Parser [(a, b, c, d, e, f, g, h, i, j, k, l, m, n)] #

(FromJSON a, FromJSON b, FromJSON c, FromJSON d, FromJSON e, FromJSON f, FromJSON g, FromJSON h, FromJSON i, FromJSON j, FromJSON k, FromJSON l, FromJSON m, FromJSON n, FromJSON o) => FromJSON (a, b, c, d, e, f, g, h, i, j, k, l, m, n, o) 

Methods

parseJSON :: Value -> Parser (a, b, c, d, e, f, g, h, i, j, k, l, m, n, o) #

parseJSONList :: Value -> Parser [(a, b, c, d, e, f, g, h, i, j, k, l, m, n, o)] #

Encoding/decoding

encodeFile :: ToJSON a => FilePath -> a -> IO () Source #

Better error information

decodeEither' :: FromJSON a => ByteString -> Either ParseException a Source #

More helpful version of decodeEither which returns the YamlException.

Since 0.8.3

decodeFileEither :: FromJSON a => FilePath -> IO (Either ParseException a) Source #

A version of decodeFile which should not throw runtime exceptions.

Since 0.8.4

More control over decoding