| Copyright | Copyright © 2015 PivotCloud, Inc. |
|---|---|
| License | MIT |
| Maintainer | Lars Kuhtz <lkuhtz@pivotmail.com> |
| Stability | experimental |
| Safe Haskell | None |
| Language | Haskell2010 |
Configuration.Utils.ConfigFile
Contents
Description
This module provides tools for defining configuration file
parsers via instances of FromJSON.
Unlike normal FromJSON instances the parsers for configuration
files are expected to yield an update function that takes
a value and updates the value with the settings from the configuration
file.
Assuming that
- all configuration types are nested Haskell records or simple types and
- that there are lenses for all record fields
usually the operators ..: and %.: are all that is needed from this module.
The module Configuration.Utils.Monoid provides tools for the case that
a simple type is a container with a monoid instance, such as List or
HashMap.
The module Configuration.Utils.Maybe explains the usage of optional
Maybe values in configuration types.
- setProperty :: Lens' α β -> Text -> (Value -> Parser β) -> Object -> Parser (α -> α)
- (..:) :: FromJSON β => Lens' α β -> Text -> Object -> Parser (α -> α)
- (!..:) :: FromJSON β => Lens' α β -> Text -> Object -> Parser (α -> α)
- updateProperty :: Lens' α β -> Text -> (Value -> Parser (β -> β)) -> Object -> Parser (α -> α)
- (%.:) :: FromJSON (β -> β) => Lens' α β -> Text -> Object -> Parser (α -> α)
- data ConfigFile
- = ConfigFileRequired {
- getConfigFile :: !Text
- | ConfigFileOptional {
- getConfigFile :: !Text
- = ConfigFileRequired {
- data ConfigFilesConfig = ConfigFilesConfig {}
- cfcHttpsPolicy :: Lens' ConfigFilesConfig HttpsCertPolicy
- defaultConfigFilesConfig :: ConfigFilesConfig
- pConfigFilesConfig :: MParser ConfigFilesConfig
- dropAndUncaml :: Int -> String -> String
- module Data.Aeson
Parsing of Configuration Files with Default Values
Arguments
| :: Lens' α β | a lens into the target that is updated by the parser |
| -> Text | the JSON property name |
| -> (Value -> Parser β) | the JSON |
| -> Object | |
| -> Parser (α -> α) |
A JSON Value parser for a property of a given
Object that updates a setter with the parsed value.
data Auth = Auth
{ _userId ∷ !Int
, _pwd ∷ !String
}
userId ∷ Functor φ ⇒ (Int → φ Int) → Auth → φ Auth
userId f s = (\u → s { _userId = u }) <$> f (_userId s)
pwd ∷ Functor φ ⇒ (String → φ String) → Auth → φ Auth
pwd f s = (\p → s { _pwd = p }) <$> f (_pwd s)
-- or with lenses and TemplateHaskell just:
-- $(makeLenses ''Auth)
instance FromJSON (Auth → Auth) where
parseJSON = withObject "Auth" $ \o → id
<$< setProperty user "user" p o
<*< setProperty pwd "pwd" parseJSON o
where
p = withText "user" $ \case
"alice" → pure (0 ∷ Int)
"bob" → pure 1
e → fail $ "unrecognized user " ⊕ e(..:) :: FromJSON β => Lens' α β -> Text -> Object -> Parser (α -> α) infix 6 Source #
A variant of the setProperty that uses the default parseJSON method from the
FromJSON instance to parse the value of the property. Its usage pattern mimics the
usage pattern of the .: operator from the aeson library.
data Auth = Auth
{ _user ∷ !String
, _pwd ∷ !String
}
user ∷ Functor φ ⇒ (String → φ String) → Auth → φ Auth
user f s = (\u → s { _user = u }) <$> f (_user s)
pwd ∷ Functor φ ⇒ (String → φ String) → Auth → φ Auth
pwd f s = (\p → s { _pwd = p }) <$> f (_pwd s)
-- or with lenses and TemplateHaskell just:
-- $(makeLenses ''Auth)
instance FromJSON (Auth → Auth) where
parseJSON = withObject "Auth" $ \o → id
<$< user ..: "user" × o
<*< pwd ..: "pwd" × o(!..:) :: FromJSON β => Lens' α β -> Text -> Object -> Parser (α -> α) Source #
This operator requires that a value is explicitly provided in a configuration file, thus preventing the default value from being used. Otherwise this operator does the same as '(..:)'.
updateProperty :: Lens' α β -> Text -> (Value -> Parser (β -> β)) -> Object -> Parser (α -> α) Source #
A JSON parser for a function that modifies a property
of a given Object and updates a setter with the parsed
function.
data HttpURL = HttpURL
{ _auth ∷ !Auth
, _domain ∷ !String
}
auth ∷ Functor φ ⇒ (Auth → φ Auth) → HttpURL → φ HttpURL
auth f s = (\u → s { _auth = u }) <$> f (_auth s)
domain ∷ Functor φ ⇒ (String → φ String) → HttpURL → φ HttpURL
domain f s = (\u → s { _domain = u }) <$> f (_domain s)
path ∷ Functor φ ⇒ (String → φ String) → HttpURL → φ HttpURL
path f s = (\u → s { _path = u }) <$> f (_path s)
-- or with lenses and TemplateHaskell just:
-- $(makeLenses ''HttpURL)
instance FromJSON (HttpURL → HttpURL) where
parseJSON = withObject "HttpURL" $ \o → id
<$< auth %.: "auth" × o
<*< domain ..: "domain" × o(%.:) :: FromJSON (β -> β) => Lens' α β -> Text -> Object -> Parser (α -> α) infix 6 Source #
A variant of updateProperty that used the FromJSON instance
for the update function. It mimics the aeson operator .:.
It creates a parser that modifies a setter with a parsed function.
data HttpURL = HttpURL
{ _auth ∷ !Auth
, _domain ∷ !String
}
auth ∷ Functor φ ⇒ (Auth → φ Auth) → HttpURL → φ HttpURL
auth f s = (\u → s { _auth = u }) <$> f (_auth s)
domain ∷ Functor φ ⇒ (String → φ String) → HttpURL → φ HttpURL
domain f s = (\u → s { _domain = u }) <$> f (_domain s)
path ∷ Functor φ ⇒ (String → φ String) → HttpURL → φ HttpURL
path f s = (\u → s { _path = u }) <$> f (_path s)
-- or with lenses and TemplateHaskell just:
-- $(makeLenses ''HttpURL)
instance FromJSON (HttpURL → HttpURL) where
parseJSON = withObject "HttpURL" $ \o → id
<$< auth %.: "auth" × o
<*< domain ..: "domain" × oConfiguration File Parsing Policy
data ConfigFile Source #
Constructors
| ConfigFileRequired | |
Fields
| |
| ConfigFileOptional | |
Fields
| |
Instances
data ConfigFilesConfig Source #
An internal type for the meta configuration that specifies how the configuration files are loaded and parsed.
Constructors
| ConfigFilesConfig | |
Fields | |
Instances
Miscellaneous Utilities
module Data.Aeson