YamlParse.Applicative

Yamlparse applicative

Implement Yaml parsing and get documentation for it for free.

Usage example

For more examples, see the `yamlparse-applicative-demo` examples in the github repository

Suppose you have some tool and you want to have it read its configuration from a file. You make a type for the configuration:

data Configuration
  = Configuration
  { confUrl :: Maybe Text
  , confPort :: Int
  , confToken :: Text
  } deriving (Show, Eq)

Instead of implementing a FromJSON instance, you now implement a YamlSchema instance like so:

instance YamlSchema Configuration where
  yamlSchema =
    objectParser $ -- Declare that it is a Yaml object
      Configuration
        <$> optionalField -- An optional key may be in the file
            "url"
            "The url to host the server at. It will be hosted on 'localhost' by default."
        <*> optionalFieldWithDefault -- An optional key with default _may_ in the file, the default will be used otherwise
            "port"
            8000
            "The post to host the server at."
        <*> requiredField -- A required field must be in the file
            "token"
            "The authorisation token that clients can use to authenticate themselves."

Now you've already documented the configuration in code. This will make sure that your documentation stays correct because it will be type-checked.

Now you can implement FromJSON like so:

instance FromJSON Configuration where
  parseJSON = viaYamlSchema

And you can get user-facing documentation about the format for free using 'prettySchema . explainParser':

# Configuration
url: # optional
  # The url to host the server at. It will be hosted on 'localhost' by default.
  <string>
port: # optional, default: 8000
  # The post to host the server at.
  <number>
token: # required
  # The authorisation token that clients can use to authenticate themselves.
  <bool>

If you are also using 'optparse-applicative', you can even add this documentation to your `--help` page as well using confDesc:

argParser :: ParserInfo SomethingElse
argParser =
  info
    (helper <$> parseSomethingElse)
    (confDesc @Configuration)

The YamlSchema Class

class YamlSchema a where

A class of types for which a schema is defined.

Note that you do not have to use this class and can just use your own parser values. Note also that the parsing of a type of this class should correspond to the parsing of the type in the FromJSON class.

Minimal complete definition

yamlSchema

Methods

yamlSchema :: YamlParser a

A yamlschema for one value

See the sections on helper functions for implementing this for plenty of examples.

yamlSchemaList :: YamlParser [a]

A yamlschema for a list of values

This is really only useful for cases like Char and String

Instances

YamlSchema Bool

Defined in YamlParse.Applicative.Class

Methods

yamlSchema :: YamlParser Bool

yamlSchemaList :: YamlParser [Bool]

YamlSchema Char

Defined in YamlParse.Applicative.Class

Methods

yamlSchema :: YamlParser Char

yamlSchemaList :: YamlParser [Char]

YamlSchema Int

Defined in YamlParse.Applicative.Class

Methods

yamlSchema :: YamlParser Int

yamlSchemaList :: YamlParser [Int]

YamlSchema Int8

Defined in YamlParse.Applicative.Class

Methods

yamlSchema :: YamlParser Int8

yamlSchemaList :: YamlParser [Int8]

YamlSchema Int16

Defined in YamlParse.Applicative.Class

Methods

yamlSchema :: YamlParser Int16

yamlSchemaList :: YamlParser [Int16]

YamlSchema Int32

Defined in YamlParse.Applicative.Class

Methods

yamlSchema :: YamlParser Int32

yamlSchemaList :: YamlParser [Int32]

YamlSchema Int64

Defined in YamlParse.Applicative.Class

Methods

yamlSchema :: YamlParser Int64

yamlSchemaList :: YamlParser [Int64]

YamlSchema Word

Defined in YamlParse.Applicative.Class

Methods

yamlSchema :: YamlParser Word

yamlSchemaList :: YamlParser [Word]

YamlSchema Word8

Defined in YamlParse.Applicative.Class

Methods

yamlSchema :: YamlParser Word8

yamlSchemaList :: YamlParser [Word8]

YamlSchema Word16

Defined in YamlParse.Applicative.Class

Methods

yamlSchema :: YamlParser Word16

yamlSchemaList :: YamlParser [Word16]

YamlSchema Word32

Defined in YamlParse.Applicative.Class

Methods

yamlSchema :: YamlParser Word32

yamlSchemaList :: YamlParser [Word32]

YamlSchema Word64

Defined in YamlParse.Applicative.Class

Methods

yamlSchema :: YamlParser Word64

yamlSchemaList :: YamlParser [Word64]

YamlSchema ()

Defined in YamlParse.Applicative.Class

Methods

yamlSchema :: YamlParser ()

yamlSchemaList :: YamlParser [()]

YamlSchema Scientific

Defined in YamlParse.Applicative.Class

Methods

yamlSchema :: YamlParser Scientific

yamlSchemaList :: YamlParser [Scientific]

YamlSchema Text

Defined in YamlParse.Applicative.Class

Methods

yamlSchema :: YamlParser Text

yamlSchemaList :: YamlParser [Text]

YamlSchema Value

Defined in YamlParse.Applicative.Class

Methods

yamlSchema :: YamlParser Value

yamlSchemaList :: YamlParser [Value]

YamlSchema a => YamlSchema [a]

Defined in YamlParse.Applicative.Class

Methods

yamlSchema :: YamlParser [a]

yamlSchemaList :: YamlParser [[a]]

YamlSchema a => YamlSchema (Maybe a)

Defined in YamlParse.Applicative.Class

Methods

yamlSchema :: YamlParser (Maybe a)

yamlSchemaList :: YamlParser [Maybe a]

YamlSchema v => YamlSchema (KeyMap v)

There is no instance using YamlKeySchema k yet. Ideally there wouldn't be one for HashMap Text either because it's insecure, but the yaml arrives in a HashMap anyway so we might as well expose this.

Defined in YamlParse.Applicative.Class

Methods

yamlSchema :: YamlParser (KeyMap v)

yamlSchemaList :: YamlParser [KeyMap v]

YamlSchema a => YamlSchema (NonEmpty a)

Defined in YamlParse.Applicative.Class

Methods

yamlSchema :: YamlParser (NonEmpty a)

yamlSchemaList :: YamlParser [NonEmpty a]

(Ord a, YamlSchema a) => YamlSchema (Set a)

Defined in YamlParse.Applicative.Class

Methods

yamlSchema :: YamlParser (Set a)

yamlSchemaList :: YamlParser [Set a]

YamlSchema a => YamlSchema (Vector a)

Defined in YamlParse.Applicative.Class

Methods

yamlSchema :: YamlParser (Vector a)

yamlSchemaList :: YamlParser [Vector a]

(Ord k, YamlKeySchema k, YamlSchema v) => YamlSchema (Map k v)

Defined in YamlParse.Applicative.Class

Methods

yamlSchema :: YamlParser (Map k v)

yamlSchemaList :: YamlParser [Map k v]

YamlSchema (Path Abs File)

Defined in YamlParse.Applicative.Class

Methods

yamlSchema :: YamlParser (Path Abs File)

yamlSchemaList :: YamlParser [Path Abs File]

YamlSchema (Path Abs Dir)

Defined in YamlParse.Applicative.Class

Methods

yamlSchema :: YamlParser (Path Abs Dir)

yamlSchemaList :: YamlParser [Path Abs Dir]

YamlSchema (Path Rel File)

Defined in YamlParse.Applicative.Class

Methods

yamlSchema :: YamlParser (Path Rel File)

yamlSchemaList :: YamlParser [Path Rel File]

YamlSchema (Path Rel Dir)

Defined in YamlParse.Applicative.Class

Methods

yamlSchema :: YamlParser (Path Rel Dir)

yamlSchemaList :: YamlParser [Path Rel Dir]

class YamlKeySchema a where

A class of types for which a schema for keys is defined.

Methods

yamlKeySchema :: KeyParser a

Instances

YamlKeySchema String

Defined in YamlParse.Applicative.Class

Methods

yamlKeySchema :: KeyParser String

YamlKeySchema Text

Defined in YamlParse.Applicative.Class

Methods

yamlKeySchema :: KeyParser Text

Implementing YamlSchema instances

objectParser :: Text -> ObjectParser o -> YamlParser o

Declare a parser of a named object

unnamedObjectParser :: ObjectParser o -> YamlParser o

Declare a parser of an unnamed object

Prefer objectParser if you can.

maybeParser :: Show o => (o -> Maybe u) -> Parser i o -> Parser i u

Make a parser that parses a value using the given extra parsing function

You can use this to make a parser for a type with a smart constructor. Prefer eitherParser if you can so you get better error messages.

Example:

parseUsername :: Text -> Maybe Username

instance YamlSchema Username where
  yamlSchema = maybeParser parseUsername yamlSchema

eitherParser :: Show o => (o -> Either String u) -> Parser i o -> Parser i u

Make a parser that parses a value using the given extra parsing function

You can use this to make a parser for a type with a smart constructor. If you don't have a Show instance for your o, then you can use extraParser instead.

Example:

parseUsername :: Text -> Either String Username

instance YamlSchema Username where
  yamlSchema = eitherParser parseUsername yamlSchema

extraParser :: (o -> Parser u) -> Parser i o -> Parser i u

Make a parser that parses a value using the given extra parsing function

You can use this to make a parser for a type with a smart constructor. Prefer eitherParser if you can, use this if you don't have a Show instance for your o.

(<?>) :: Parser i a -> Text -> Parser i a

Add a comment to a parser

This info will be used in the schema for documentation.

For example:

data Result = Error | Ok
instance YamlSchema Result where
  yamlSchema = alternatives
    [ Error <$ literalString "Error" <?> "An error"
    , Ok <$ literalString "Ok" <?> "Oll Klear"
    ]

(<??>) :: Parser i a -> [Text] -> Parser i a

Add a list of lines of comments to a parser

This info will be used in the schema for documentation.

For example:

data Result = Error | Ok
instance YamlSchema Result where
  yamlSchema = alternatives
    [ Error <$ literalString "Error" <??> ["Just an error", "but I've got a lot to say about this"]
    , Ok <$ literalString "Ok" <??> ["Oll Klear", "I really don't know where 'OK' comes from?!"]
    ]

requiredField :: YamlSchema a => Text -> Text -> ObjectParser a

A parser for a required field in an object at a given key

requiredField' :: YamlSchema a => Text -> ObjectParser a

A parser for a required field in an object at a given key without a help text

requiredFieldWith :: Text -> Text -> YamlParser a -> ObjectParser a

A parser for a required field at a given key with a parser for what is found at that key

requiredFieldWith' :: Text -> YamlParser a -> ObjectParser a

A parser for a required field at a given key with a parser for what is found at that key without a help text

optionalField :: YamlSchema a => Text -> Text -> ObjectParser (Maybe a)

A parser for an optional field in an object at a given key

optionalField' :: YamlSchema a => Text -> ObjectParser (Maybe a)

A parser for an optional field in an object at a given key without a help text

optionalFieldWith :: Text -> Text -> YamlParser a -> ObjectParser (Maybe a)

A parser for an optional field at a given key with a parser for what is found at that key

optionalFieldWith' :: Text -> YamlParser a -> ObjectParser (Maybe a)

A parser for an optional field at a given key with a parser for what is found at that key without a help text

optionalFieldWithDefault :: (Show a, YamlSchema a) => Text -> a -> Text -> ObjectParser a

A parser for an optional field in an object at a given key with a default value

optionalFieldWithDefault' :: (Show a, YamlSchema a) => Text -> a -> ObjectParser a

A parser for an optional field in an object at a given key with a default value without a help text

optionalFieldWithDefaultWith :: Show a => Text -> a -> Text -> YamlParser a -> ObjectParser a

A parser for an optional field at a given key with a default value and a parser for what is found at that key

For the sake of documentation, the default value needs to be showable.

optionalFieldWithDefaultWith' :: Show a => Text -> a -> YamlParser a -> ObjectParser a

A parser for an optional field at a given key with a default value and a parser for what is found at that key without a help text

For the sake of documentation, the default value needs to be showable.

viaRead :: Read a => YamlParser a

Parse a string-like thing by Read-ing it

You probably don't want to use Read.

literalString :: Text -> YamlParser Text

Declare a parser for an exact string.

You can use this to parse a constructor in an enum for example:

data Fruit = Apple | Banana

instance YamlSchema Fruit where
  yamlSchema = Apple <$ literalString "Apple" <|> Banana <$ literalString "Banana"

literalValue :: ToJSON a => a -> YamlParser a

Declare a parser for a value using its show instance

Note that no value is read. The parsed string is just compared to the shown given value.

You can use this to parse a constructor in an enum when it has a ToJSON instance.

For example

data Fruit = Apple | Banana | Melon
  deriving (Eq, Generic)

instance ToJSON Fruit

instance YamlSchema Fruit where
  yamlSchema = alternatives
     [ literalValue Apple
     , literalValue Banana
     , literalValue Melon
     ]

literalShowValue :: Show a => a -> YamlParser a

Declare a parser for a value using its show instance

Note that no value is read. The parsed string is just compared to the shown given value.

You can use this to parse a constructor in an enum when it has a Show instance.

For example:

data Fruit = Apple | Banana | Melon
  deriving (Show, Eq)

instance YamlSchema Fruit where
  yamlSchema = alternatives
     [ literalShowString Apple
     , literalShowString Banana
     , literalShowString Melon
     ]

alternatives :: [Parser i o] -> Parser i o

Use the first parser of the given list that succeeds

You can use this to parse a constructor in an enum.

For example:

data Fruit = Apple | Banana | Melon

instance YamlSchema Fruit where
  yamlSchema = alternatives
     [ Apple <$ literalString "Apple"
     , Banana <$ literalString "Banana"
     , Melon <$ literalString "Melon"
     ]

Parser

type YamlParser a = Parser Value a

type ObjectParser a = Parser Object a

data Parser i o where

A parser that takes values of type i as input and parses them into values of type o

Note that there is no Monad instance.

Constructors

ParseAny :: Parser i i

Return the input

ParseExtra :: (o -> Parser u) -> Parser i o -> Parser i u

Parse via an extra parsing function

ParseEq

Match an exact value

Fields

• :: (Show o, Eq o)
• => o
• -> Text

  Shown version of the o in the previous argument

• -> Parser i o
• -> Parser i o

ParseNull :: Parser Value ()

Parse null only.

ParseMaybe :: Parser Value o -> Parser Value (Maybe o)

Parse null as Nothing and the rest as Just.

ParseBool :: Maybe Text -> Parser Bool o -> Parser Value o

Parse a boolean value

ParseString

Parse a String value

Fields

• :: Maybe Text

  Extra info about what the string represents This info will be used during parsing for error messages and in the schema for documentation.

• -> Parser Text o
• -> Parser Value o

ParseNumber

Parse a numeric value

Fields

• :: Maybe Text

  Extra info about what the number represents This info will be used during parsing for error messages and in the schema for documentation.

• -> Parser Scientific o
• -> Parser Value o

ParseArray

Parse an array

Fields

• :: Maybe Text

  Extra info about what the array represents This info will be used during parsing for error messages and in the schema for documentation.

• -> Parser Array o
• -> Parser Value o

ParseObject

Parse an object

Fields

• :: Maybe Text

  Extra info about what the object represents This info will be used during parsing for error messages and in the schema for documentation.

• -> Parser Object a
• -> Parser Value a

ParseList :: Parser Value o -> Parser Array (Vector o)

Parse a list of elements all in the same way

ParseMap :: Parser Value v -> Parser Object (KeyMap v)

Parse a map where the keys are the yaml keys

ParseMapKeys :: Ord k => Parser Text k -> Parser Object (KeyMap v) -> Parser Object (Map k v)

Parse a map's keys via a given parser

ParseField

Parse a field of an object

Fields

• :: Text

  The key of the field

• -> FieldParser o
• -> Parser Object o

ParsePure :: a -> Parser i a

A pure value

ParseFmap :: (a -> b) -> Parser i a -> Parser i b

To implement Functor

ParseAp :: Parser i (a -> b) -> Parser i a -> Parser i b

To implement Applicative

ParseAlt :: [Parser i o] -> Parser i o

To implement Alternative

ParseComment :: Text -> Parser i o -> Parser i o

Add comments to the parser. This info will be used in the schema for documentation.

Instances

Functor (Parser i)

Defined in YamlParse.Applicative.Parser

Methods

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

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

Applicative (Parser i)

Defined in YamlParse.Applicative.Parser

Methods

pure :: a -> Parser i a

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

liftA2 :: (a -> b -> c) -> Parser i a -> Parser i b -> Parser i c

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

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

Alternative (Parser i)

Defined in YamlParse.Applicative.Parser

Methods

empty :: Parser i a

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

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

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

data FieldParser o where

Constructors

FieldParserFmap :: (a -> b) -> FieldParser a -> FieldParser b

FieldParserRequired :: YamlParser o -> FieldParser o

FieldParserOptional :: YamlParser o -> FieldParser (Maybe o)

FieldParserOptionalWithDefault :: Show o => YamlParser o -> o -> FieldParser o

Instances

Functor FieldParser

Defined in YamlParse.Applicative.Parser

Methods

fmap :: (a -> b) -> FieldParser a -> FieldParser b

(<$) :: a -> FieldParser b -> FieldParser a

Using a yaml schema

Parsing Yaml via a YamlSchema instance

viaYamlSchema :: YamlSchema a => Value -> Parser a

Helper function to implement FromJSON via YamlSchema

Example:

instance FromJSON Config where
  parseJSON = viaYamlSchema

newtype ViaYamlSchema a

A helper newtype to parse a yaml value using the YamlSchema parser.

Example:

case Data.Yaml.decodeEither' contents of
  Left e -> die $ show e
  Right (ViaYamlSchema res) -> print res

This only helps you when you really don't want to implement a FromJSON instance. See viaYamlSchema if you do.

Constructors

ViaYamlSchema a

Instances

Eq a => Eq (ViaYamlSchema a)

Defined in YamlParse.Applicative.Class

Methods

(==) :: ViaYamlSchema a -> ViaYamlSchema a -> Bool

(/=) :: ViaYamlSchema a -> ViaYamlSchema a -> Bool

Show a => Show (ViaYamlSchema a)

Defined in YamlParse.Applicative.Class

Methods

showsPrec :: Int -> ViaYamlSchema a -> ShowS

show :: ViaYamlSchema a -> String

showList :: [ViaYamlSchema a] -> ShowS

Generic (ViaYamlSchema a)

Defined in YamlParse.Applicative.Class

Associated Types

type Rep (ViaYamlSchema a) :: Type -> Type

Methods

from :: ViaYamlSchema a -> Rep (ViaYamlSchema a) x

to :: Rep (ViaYamlSchema a) x -> ViaYamlSchema a

YamlSchema a => FromJSON (ViaYamlSchema a)

Defined in YamlParse.Applicative.Class

Methods

parseJSON :: Value -> Parser (ViaYamlSchema a)

parseJSONList :: Value -> Parser [ViaYamlSchema a]

type Rep (ViaYamlSchema a)

Defined in YamlParse.Applicative.Class

type Rep (ViaYamlSchema a) = D1 ('MetaData "ViaYamlSchema" "YamlParse.Applicative.Class" "yamlparse-applicative-0.2.0.1-1uPqPozBoBO1cU6nvRn5zo" 'True) (C1 ('MetaCons "ViaYamlSchema" 'PrefixI 'False) (S1 ('MetaSel ('Nothing :: Maybe Symbol) 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 a)))

Getting a parser implemntation from a Parser

implementParser :: Parser i o -> i -> Parser o

Use a Parser to parse a value from Yaml.

A 'Parser i o' corresponds exactly to a 'i -> Yaml.Parser o' and this function servers as evidence for that.

Documentation for a Parser

prettySchemaDoc :: forall a. YamlSchema a => Text

Render pretty documentation about the yamlSchema of a type

This is meant for humans. The output may look like YAML but it is not.

prettyParserDoc :: Parser i o -> Text

Render pretty documentation about a parser

This is meant for humans. The output may look like YAML but it is not.

prettyColourisedSchemaDoc :: forall a. YamlSchema a => Text

Render pretty colourised documentation about the yamlSchema of a type

This is meant for humans. The output may look like YAML but it is not.

prettyColourisedParserDoc :: Parser i o -> Text

Render pretty colourised documentation about a parser

This is meant for humans. The output may look like YAML but it is not.

Parser schemas

explainParser :: Parser i o -> Schema

Use a parser to produce a schema that describes it for documentation.

Nothing means that nothing even needs to be parsed, you just get the a without parsing anything. This is for the pure case.

data Schema

Constructors

EmptySchema

AnySchema

ExactSchema Text

NullSchema

MaybeSchema Schema

BoolSchema (Maybe Text)

NumberSchema (Maybe Text)

StringSchema (Maybe Text)

ArraySchema (Maybe Text) Schema

ObjectSchema (Maybe Text) Schema

FieldSchema Text Bool (Maybe Text) Schema

ListSchema Schema

MapSchema Schema

MapKeysSchema Schema

ApSchema Schema Schema

AltSchema [Schema]

CommentSchema Text Schema

Instances

Eq Schema

Defined in YamlParse.Applicative.Explain

Methods

(==) :: Schema -> Schema -> Bool

(/=) :: Schema -> Schema -> Bool

Show Schema

Defined in YamlParse.Applicative.Explain

Methods

showsPrec :: Int -> Schema -> ShowS

show :: Schema -> String

showList :: [Schema] -> ShowS

Generic Schema

Defined in YamlParse.Applicative.Explain

Associated Types

type Rep Schema :: Type -> Type

Methods

from :: Schema -> Rep Schema x

to :: Rep Schema x -> Schema

Validity Schema

Defined in YamlParse.Applicative.Explain

Methods

validate :: Schema -> Validation

type Rep Schema

Defined in YamlParse.Applicative.Explain

type Rep Schema = D1 ('MetaData "Schema" "YamlParse.Applicative.Explain" "yamlparse-applicative-0.2.0.1-1uPqPozBoBO1cU6nvRn5zo" 'False) ((((C1 ('MetaCons "EmptySchema" 'PrefixI 'False) (U1 :: Type -> Type) :+: C1 ('MetaCons "AnySchema" 'PrefixI 'False) (U1 :: Type -> Type)) :+: (C1 ('MetaCons "ExactSchema" 'PrefixI 'False) (S1 ('MetaSel ('Nothing :: Maybe Symbol) 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 Text)) :+: C1 ('MetaCons "NullSchema" 'PrefixI 'False) (U1 :: Type -> Type))) :+: ((C1 ('MetaCons "MaybeSchema" 'PrefixI 'False) (S1 ('MetaSel ('Nothing :: Maybe Symbol) 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 Schema)) :+: C1 ('MetaCons "BoolSchema" 'PrefixI 'False) (S1 ('MetaSel ('Nothing :: Maybe Symbol) 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 (Maybe Text)))) :+: (C1 ('MetaCons "NumberSchema" 'PrefixI 'False) (S1 ('MetaSel ('Nothing :: Maybe Symbol) 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 (Maybe Text))) :+: C1 ('MetaCons "StringSchema" 'PrefixI 'False) (S1 ('MetaSel ('Nothing :: Maybe Symbol) 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 (Maybe Text)))))) :+: (((C1 ('MetaCons "ArraySchema" 'PrefixI 'False) (S1 ('MetaSel ('Nothing :: Maybe Symbol) 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 (Maybe Text)) :*: S1 ('MetaSel ('Nothing :: Maybe Symbol) 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 Schema)) :+: C1 ('MetaCons "ObjectSchema" 'PrefixI 'False) (S1 ('MetaSel ('Nothing :: Maybe Symbol) 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 (Maybe Text)) :*: S1 ('MetaSel ('Nothing :: Maybe Symbol) 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 Schema))) :+: (C1 ('MetaCons "FieldSchema" 'PrefixI 'False) ((S1 ('MetaSel ('Nothing :: Maybe Symbol) 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 Text) :*: S1 ('MetaSel ('Nothing :: Maybe Symbol) 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 Bool)) :*: (S1 ('MetaSel ('Nothing :: Maybe Symbol) 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 (Maybe Text)) :*: S1 ('MetaSel ('Nothing :: Maybe Symbol) 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 Schema))) :+: C1 ('MetaCons "ListSchema" 'PrefixI 'False) (S1 ('MetaSel ('Nothing :: Maybe Symbol) 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 Schema)))) :+: ((C1 ('MetaCons "MapSchema" 'PrefixI 'False) (S1 ('MetaSel ('Nothing :: Maybe Symbol) 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 Schema)) :+: C1 ('MetaCons "MapKeysSchema" 'PrefixI 'False) (S1 ('MetaSel ('Nothing :: Maybe Symbol) 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 Schema))) :+: (C1 ('MetaCons "ApSchema" 'PrefixI 'False) (S1 ('MetaSel ('Nothing :: Maybe Symbol) 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 Schema) :*: S1 ('MetaSel ('Nothing :: Maybe Symbol) 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 Schema)) :+: (C1 ('MetaCons "AltSchema" 'PrefixI 'False) (S1 ('MetaSel ('Nothing :: Maybe Symbol) 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 [Schema])) :+: C1 ('MetaCons "CommentSchema" 'PrefixI 'False) (S1 ('MetaSel ('Nothing :: Maybe Symbol) 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 Text) :*: S1 ('MetaSel ('Nothing :: Maybe Symbol) 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 Schema)))))))

Showing the schema to the user

prettySchema :: Schema -> Text

Render a schema as pretty text.

This is meant for humans. The output may look like YAML but it is not.

prettyColourisedSchema :: Schema -> Text

Render a schema as pretty and colourised text.

This is meant for humans. The output may look like YAML but it is not.

Interface with 'optparse-applicative'

confDesc :: forall o a. YamlSchema o => InfoMod a

Helper function to add the schema documentation for a YamlSchema parser to the optparse applicative help output

confDescWith :: Parser i o -> InfoMod a

Helper function to add the schema documentation for a given parser to the optparse applicative help output

Parsing a file

readConfigFile :: (YamlSchema a, FromJSON a) => Path r File -> IO (Maybe a)

Helper function to read a config file for a type in YamlSchema

readFirstConfigFile :: forall a r. (FromJSON a, YamlSchema a) => [Path r File] -> IO (Maybe a)

Helper function to read the first in a list of config files