Data.Yaml.Config.Internal

Types

data Config

Type contains config section and path from root.

Constructors

Config [Key] Object

Instances

Eq Config

Show Config

NFData Config

newtype KeyError

This error can be raised if config has not target path.

Constructors

KeyError Key

Instances

Show KeyError

Exception KeyError

type Key = Text

Config or field name

Loading

load :: FilePath -> IO Config

Attempts to load a config from a given YAML file. Fails with InvalidYaml if the file does not exist.

>>> config <- load "example.yaml"

Access functions

keys :: Config -> [Key]

Returns all toplevel keys in a config.

>>> keys config
["section1","section2"]

subconfig

Arguments

:: Monad m

=> Key

Subconfig name

-> Config

(Sub)Config to narrow into

-> m Config

Subconfig

Narrows into a config section corresponding to a given key. Fails with a KeyError if a key doesn't exist at the current level.

>>> :set -XOverloadedStrings
>>> sub <- subconfig "section1" config

lookup

Arguments

:: (Monad m, FromJSON a)

=> Key

Field name

-> Config

Config to query

-> m a

Looked up value

Returns a value for a given key. Fails with a KeyError if the key doesn't exist.

>>> keys sub
["field1","field2"]
>>> putStrLn =<< lookup "field1" sub
value1

lookupDefault

Arguments

:: FromJSON a

=> Key

Field name

-> a

Default value

-> Config

Config to query

-> a

Looked up or default value

Returns a value for a given key or a default value if a key doesn't exist.

>>> lookupDefault "field3" "def" sub
"def"

fullpath :: Config -> Key -> Key

Returns full path from the root to the given key. Levels are separated by dots.

>>> fullpath sub "field1"
"section1.field1"