Data.Salak

Configuration Loader for Production in Haskell.

How to use this library

| This library default a standard configuration load process. It can load properties from CommandLine, Environment, `JSON value` and Yaml files. They all load to the same format Properties. Earler property source has higher order to load property. For example:

CommandLine:  --package.a.enabled=true
Environment: PACKAGE_A_ENABLED: false

lookup "package.a.enabled" properties => Just True

CommandLine has higher order then Environment, for the former load properties earler then later.

Usage:

data Config = Config
  { name :: Text
  , dir  :: Maybe Text
  , ext  :: Int
  } deriving (Eq, Show)

instance FromJSON Config where
  parseJSON = withObject "Config" $ \v -> Config
        <$> v .:  "name"
        <*> v .:? "dir"
        <*> (fromMaybe 1 <$> v .:? "ext")

main = do
  p <- defaultPropertiesWithFile "salak.yml"
  let Just config = lookup "salak.config" p :: Maybe Config
  print config

Properties Loader

defaultProperties :: IO Properties

Initialize default properties from CommandLine and Environment. CommandLine use default parser.

type ParseCommandLine = [String] -> IO [(String, Property)]

CommandLine parser. Parse command line into property key values.

defaultProperties' :: ParseCommandLine -> IO Properties

Initialize default properties from CommandLine and Environment.

defaultPropertiesWithFile

Arguments

:: FileName

specify default config file name, can reset by config "salak.config.name" from CommandLine or Environment.

-> IO Properties

Initialize default properties from CommandLine, Environment and Yaml files. All these configuration sources has orders, from highest order to lowest order:

1. CommandLine
2. Environment
3. Specified Yaml file(file in "salak.config.dir")
4. Yaml file in current directory
5. Yaml file in home directory

defaultPropertiesWithFile'

Arguments

:: FileName

specify default config file name, can reset by config "salak.config.name" from CommandLine or Environment.

-> ParseCommandLine

parser for command line

-> IO Properties

Initialize default properties from CommandLine, Environment and Yaml files. All these configuration sources has orders, from highest order to lowest order:

1. CommandLine
2. Environment
3. Specified Yaml file(file in "salak.config.dir")
4. Yaml file in current directory
5. Yaml file in home directory

empty :: Properties

The empty Properties

Lookup Properties

lookup :: FromProperties a => Text -> Properties -> Maybe a

Find Properties by key and convert to specific Haskell value. Return Nothing means not found, and throw ErrorCall means convert failed.

lookup' :: FromProperties a => Text -> Properties -> Return a

Find Properties by key and convert to specific Haskell value.

toKeys :: Text -> [Key]

Split origin key by . to sub keys:

"salak.config.name" -> ["salak","config","name"]
"" -> []
"a..b" -> ["a","b"]

Types

data Property

A Property value represented as a Haskell value.

Constructors

PNum !Scientific

Numeric Property

PStr !Text

String Property

PBool !Bool

Bool Property

Instances

Eq Property

Defined in Data.Salak.Types

Methods

(==) :: Property -> Property -> Bool

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

Show Property

Defined in Data.Salak.Types

Methods

showsPrec :: Int -> Property -> ShowS

show :: Property -> String

showList :: [Property] -> ShowS

IsString Property

Defined in Data.Salak.Types

Methods

fromString :: String -> Property

FromProperties Property

Defined in Data.Salak.Types

Methods

fromProperties :: Properties -> Return Property

data Properties

A Property Container to hold all properties

Constructors

Properties [Property] [HashMap Key Properties]

Instances

Eq Properties

Defined in Data.Salak.Types

Methods

(==) :: Properties -> Properties -> Bool

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

Show Properties

Defined in Data.Salak.Types

Methods

showsPrec :: Int -> Properties -> ShowS

show :: Properties -> String

showList :: [Properties] -> ShowS

type Key = Text

Property key

class FromProperties a where

Convert Properties to Haskell value.

Methods

fromProperties :: Properties -> Return a

Instances

FromProperties Bool

Defined in Data.Salak.Types

Methods

fromProperties :: Properties -> Return Bool

FromProperties Char

Defined in Data.Salak.Types

Methods

fromProperties :: Properties -> Return Char

FromProperties Double

Defined in Data.Salak.Types

Methods

fromProperties :: Properties -> Return Double

FromProperties Float

Defined in Data.Salak.Types

Methods

fromProperties :: Properties -> Return Float

FromProperties Int

Defined in Data.Salak.Types

Methods

fromProperties :: Properties -> Return Int

FromProperties Int8

Defined in Data.Salak.Types

Methods

fromProperties :: Properties -> Return Int8

FromProperties Int16

Defined in Data.Salak.Types

Methods

fromProperties :: Properties -> Return Int16

FromProperties Int32

Defined in Data.Salak.Types

Methods

fromProperties :: Properties -> Return Int32

FromProperties Int64

Defined in Data.Salak.Types

Methods

fromProperties :: Properties -> Return Int64

FromProperties Word

Defined in Data.Salak.Types

Methods

fromProperties :: Properties -> Return Word

FromProperties Word8

Defined in Data.Salak.Types

Methods

fromProperties :: Properties -> Return Word8

FromProperties Word16

Defined in Data.Salak.Types

Methods

fromProperties :: Properties -> Return Word16

FromProperties Word32

Defined in Data.Salak.Types

Methods

fromProperties :: Properties -> Return Word32

FromProperties Word64

Defined in Data.Salak.Types

Methods

fromProperties :: Properties -> Return Word64

FromJSON a => FromProperties a

Defined in Data.Salak.Aeson

Methods

fromProperties :: Properties -> Return a

FromProperties Scientific

Defined in Data.Salak.Types

Methods

fromProperties :: Properties -> Return Scientific

FromProperties Text

Defined in Data.Salak.Types

Methods

fromProperties :: Properties -> Return Text

FromProperties Value

Defined in Data.Salak.Aeson

Methods

fromProperties :: Properties -> Return Value

FromProperties String

Defined in Data.Salak.Types

Methods

fromProperties :: Properties -> Return String

FromProperties Property

Defined in Data.Salak.Types

Methods

fromProperties :: Properties -> Return Property

FromProperties a => FromProperties [a]

Defined in Data.Salak.Types

Methods

fromProperties :: Properties -> Return [a]

data Return a

Return of FromProperties

Constructors

Empty

OK a

Fail String

Instances

Monad Return

Defined in Data.Salak.Types

Methods

(>>=) :: Return a -> (a -> Return b) -> Return b

(>>) :: Return a -> Return b -> Return b

return :: a -> Return a

fail :: String -> Return a

Functor Return

Defined in Data.Salak.Types

Methods

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

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

Applicative Return

Defined in Data.Salak.Types

Methods

pure :: a -> Return a

(<*>) :: Return (a -> b) -> Return a -> Return b

liftA2 :: (a -> b -> c) -> Return a -> Return b -> Return c

(*>) :: Return a -> Return b -> Return b

(<*) :: Return a -> Return b -> Return a

Show a => Show (Return a)

Defined in Data.Salak.Types

Methods

showsPrec :: Int -> Return a -> ShowS

show :: Return a -> String

showList :: [Return a] -> ShowS

Properties Loader Helper

insert :: [Key] -> Property -> Properties -> Properties

Insert simple Property into Properties by Key. If the key already have values then the new property will discard.

makePropertiesFromEnvironment :: Properties -> IO Properties

Load Properties from Environment

defaultParseCommandLine :: ParseCommandLine

Default command line parsers. Use format:

--KEY=VALUE

For example:

--salak.config.name=test.yml => ("salak.config.name", PStr "test.yml")

makePropertiesFromCommandLine :: ParseCommandLine -> Properties -> IO Properties

Load Properties from CommandLine

makePropertiesFromJson :: Value -> Properties -> Properties

Load Properties from JSON Value

makePropertiesFromYaml :: FilePath -> Properties -> IO Properties

Load Properties from Yaml file.

type FileName = Text

Yaml file name.