Conferer.FromConfig

Public API module providing FromConfig functionality

Documentation

class FromConfig a where

The typeclass for defining the way to get values from a Config, hiding the Text based nature of the Sources and parse whatever value as the types sees fit

Some of these instances are provided in different packages to avoid the heavy dependencies.

It provides a reasonable default using Generics so most of the time user need not to implement this typeclass.

Minimal complete definition

Nothing

Methods

fromConfig :: Key -> Config -> IO a

This function uses a Config and a scoping Key to get a value.

Some conventions:

• When some Key is missing this function should throw MissingRequiredKey
• For any t it should hold that fetchFromConfig k (config & addDefault k t) == t meaning that a default on the same key with the right type should be used as a default and with no configuration that value should be returned
• Try desconstructing the value in as many keys as possible since is allows easier partial overriding.

default fromConfig :: (Typeable a, Generic a, IntoDefaultsG (Rep a), FromConfigG (Rep a)) => Key -> Config -> IO a

Instances

FromConfig Bool

Defined in Conferer.FromConfig.Internal

Methods

fromConfig :: Key -> Config -> IO Bool

FromConfig Float

Defined in Conferer.FromConfig.Internal

Methods

fromConfig :: Key -> Config -> IO Float

FromConfig Int

Defined in Conferer.FromConfig.Internal

Methods

fromConfig :: Key -> Config -> IO Int

FromConfig Integer

Defined in Conferer.FromConfig.Internal

Methods

fromConfig :: Key -> Config -> IO Integer

FromConfig ()

Defined in Conferer.FromConfig.Internal

Methods

fromConfig :: Key -> Config -> IO ()

Typeable a => FromConfig a

Defined in Conferer.FromConfig.Internal

Methods

fromConfig :: Key -> Config -> IO a

FromConfig String

Defined in Conferer.FromConfig.Internal

Methods

fromConfig :: Key -> Config -> IO String

FromConfig ByteString

Defined in Conferer.FromConfig.Internal

Methods

fromConfig :: Key -> Config -> IO ByteString

FromConfig ByteString

Defined in Conferer.FromConfig.Internal

Methods

fromConfig :: Key -> Config -> IO ByteString

FromConfig Text

Defined in Conferer.FromConfig.Internal

Methods

fromConfig :: Key -> Config -> IO Text

FromConfig File

Defined in Conferer.FromConfig.Internal

Methods

fromConfig :: Key -> Config -> IO File

(Typeable a, FromConfig a) => FromConfig [a]

Defined in Conferer.FromConfig.Internal

Methods

fromConfig :: Key -> Config -> IO [a]

(Typeable a, FromConfig a) => FromConfig (Maybe a)

Defined in Conferer.FromConfig.Internal

Methods

fromConfig :: Key -> Config -> IO (Maybe a)

fetchFromConfig :: forall a. (FromConfig a, Typeable a) => Key -> Config -> IO a

class DefaultConfig a where

Utility only typeclass to smooth the naming differences between default values for external library settings

This typeclass is not used internally it's only here for convinience for users

Methods

configDef :: a

fetchFromConfigWithDefault :: forall a. (Typeable a, FromConfig a) => Config -> Key -> a -> IO a

Same as fetchFromConfig but adding a user defined default before fetchFromConfiging so it doesn't throw a MissingKeyError

fetchFromRootConfig :: forall a. (FromConfig a, Typeable a) => Config -> IO a

Same as fetchFromConfig using the root key

fetchFromRootConfigWithDefault :: forall a. (Typeable a, FromConfig a) => Config -> a -> IO a

Same as fetchFromConfigWithDefault using the root key

fetchFromConfigByIsString :: (Typeable a, IsString a) => Key -> Config -> IO a

Helper function to implement fetchFromConfig using the IsString instance

fetchFromConfigByRead :: (Typeable a, Read a) => Key -> Config -> IO a

Allow the programmer to override this FromConfig instance by providing a special OverrideFromConfig value.

To avoid infinite recursion we remove the Override before calling the value

Helper function to implement fetchFromConfig using the Read instance

fetchFromConfigWith :: forall a. Typeable a => (Text -> Maybe a) -> Key -> Config -> IO a

Helper function to implement fetchFromConfig using some parsing function

addDefaultsAfterDeconstructingToDefaults

Arguments

:: forall a. Typeable a

=> (a -> [(Key, Dynamic)])

Function to deconstruct the value

-> Key

Key where to look for the value

-> Config

The config

-> IO Config

Helper function does the plumbing of desconstructing a default into smaller defaults, which is usefull for nested fetchFromConfig.

data MissingRequiredKey

Exception to show that some non optional Key was missing while trying to fetchFromConfig

Instances

Eq MissingRequiredKey

Defined in Conferer.FromConfig.Internal

Methods

(==) :: MissingRequiredKey -> MissingRequiredKey -> Bool

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

Show MissingRequiredKey

Defined in Conferer.FromConfig.Internal

Methods

showsPrec :: Int -> MissingRequiredKey -> ShowS

show :: MissingRequiredKey -> String

showList :: [MissingRequiredKey] -> ShowS

Exception MissingRequiredKey

Defined in Conferer.FromConfig.Internal

Methods

toException :: MissingRequiredKey -> SomeException

fromException :: SomeException -> Maybe MissingRequiredKey

displayException :: MissingRequiredKey -> String

throwMissingRequiredKey :: forall t a. Typeable t => Key -> IO a

Simplified helper function to throw a MissingRequiredKey

missingRequiredKey :: forall t. Typeable t => Key -> MissingRequiredKey

Simplified helper function to create a MissingRequiredKey

data ConfigParsingError

Exception to show that a value couldn't be parsed properly

Instances

Eq ConfigParsingError

Defined in Conferer.FromConfig.Internal

Methods

(==) :: ConfigParsingError -> ConfigParsingError -> Bool

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

Show ConfigParsingError

Defined in Conferer.FromConfig.Internal

Methods

showsPrec :: Int -> ConfigParsingError -> ShowS

show :: ConfigParsingError -> String

showList :: [ConfigParsingError] -> ShowS

Exception ConfigParsingError

Defined in Conferer.FromConfig.Internal

Methods

toException :: ConfigParsingError -> SomeException

fromException :: SomeException -> Maybe ConfigParsingError

displayException :: ConfigParsingError -> String

throwConfigParsingError :: forall a b. Typeable a => Key -> Text -> IO b

Helper function to throw ConfigParsingError

configParsingError :: forall a. Typeable a => Key -> Text -> ConfigParsingError

Helper function to create a ConfigParsingError

data Key

This type is used extensivelly as a way to point into a Source and in turn into a Config. The intended way to create them is is using mkKey.

It's a list of alphanumeric words and each Source can interpret it as it sees fit.

Instances

Eq Key

Defined in Conferer.Key.Internal

Methods

(==) :: Key -> Key -> Bool

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

Ord Key

Defined in Conferer.Key.Internal

Methods

compare :: Key -> Key -> Ordering

(<) :: Key -> Key -> Bool

(<=) :: Key -> Key -> Bool

(>) :: Key -> Key -> Bool

(>=) :: Key -> Key -> Bool

max :: Key -> Key -> Key

min :: Key -> Key -> Key

Show Key

Defined in Conferer.Key.Internal

Methods

showsPrec :: Int -> Key -> ShowS

show :: Key -> String

showList :: [Key] -> ShowS

IsString Key

Defined in Conferer.Key.Internal

Methods

fromString :: String -> Key

(/.) :: Key -> Key -> Key

Concatenate two keys

newtype File

A newtype wrapper for a FilePath to allow implementing FromConfig with something better than just a String

Constructors

File FilePath

Instances

Eq File

Defined in Conferer.FromConfig.Internal

Methods

(==) :: File -> File -> Bool

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

Ord File

Defined in Conferer.FromConfig.Internal

Methods

compare :: File -> File -> Ordering

(<) :: File -> File -> Bool

(<=) :: File -> File -> Bool

(>) :: File -> File -> Bool

(>=) :: File -> File -> Bool

max :: File -> File -> File

min :: File -> File -> File

Read File

Defined in Conferer.FromConfig.Internal

Methods

readsPrec :: Int -> ReadS File

readList :: ReadS [File]

readPrec :: ReadPrec File

readListPrec :: ReadPrec [File]

Show File

Defined in Conferer.FromConfig.Internal

Methods

showsPrec :: Int -> File -> ShowS

show :: File -> String

showList :: [File] -> ShowS

IsString File

Defined in Conferer.FromConfig.Internal

Methods

fromString :: String -> File

FromConfig File

Defined in Conferer.FromConfig.Internal

Methods

fromConfig :: Key -> Config -> IO File

data KeyLookupResult

Result of a key lookup in a Config

Constructors

MissingKey [Key]

FoundInSources Key Text

FoundInDefaults Key [Dynamic]

Instances

Show KeyLookupResult

Defined in Conferer.Config.Internal.Types

Methods

showsPrec :: Int -> KeyLookupResult -> ShowS

show :: KeyLookupResult -> String

showList :: [KeyLookupResult] -> ShowS

data OverrideFromConfig a

Constructors

OverrideFromConfig (Key -> Config -> IO a)

overrideFetch :: forall a. Typeable a => (Key -> Config -> IO a) -> Dynamic

Helper function to override the fetching function for a certain key.

This function creates a Dynamic that when added to the defaults allows overriding the default FromConfig instance.

fetchFromDefaults :: forall a. Typeable a => Key -> Config -> Maybe a

Fetch from value from the defaults map of a Config or else return a Nothing

fetchRequiredFromDefaults :: forall a. Typeable a => Key -> Config -> IO a

Fetch from value from the defaults map of a Config or else throw