Safe Haskell	None
Language	Haskell2010

Data.Configurator

Contents

Types
Low-level parsing
High-level parsing
- Value parsers
- Configuration parsers

Description

A simplified library for reading configuration files in the format of configurator-ng.

Synopsis

type Key = Text
data Value
- = Bool Bool
- | String Text
- | Number Scientific
- | List [Value]
type Config = Map Key Value
load :: FilePath -> IO Config
newtype ParseError = ParseError Text
data Parser a b
runParser :: Parser a b -> a -> Either Text b
bool :: Parser Value Bool
int :: Parser Value Int
string :: Parser Value Text
value :: Parser Value Value
list :: Parser Value a -> Parser Value [a]
optional :: Key -> Parser Value a -> Parser Config (Maybe a)
required :: Key -> Parser Value a -> Parser Config a
subassocs :: Key -> Parser Value a -> Parser Config [(Key, a)]

Types

type Key = Text Source #

The left-hand side of a configuration binding.

data Value Source #

A general right-hand side value of a configuration binding.

Constructors

Bool Bool	A Boolean. Represented in a configuration file as `on` or `off`, `true` or `false` (case sensitive).
String Text	A Unicode string. Represented in a configuration file as text surrounded by double quotes. Escape sequences: `\n` - newline `\r` - carriage return `\t` - horizontal tab `\\` - backslash `\"` - quotes `\u`xxxx - Unicode character, encoded as four hexadecimal digits `\u`xxxx`\u`xxxx - Unicode character (as two UTF-16 surrogates)
Number Scientific	A number.
List [Value]	A heterogeneous list. Represented in a configuration file as an opening square bracket "`[`", followed by a comma-separated series of values, ending with a closing square bracket "`]`".

Instances

Eq Value Source #
Instance details Defined in Data.Configurator.Types Methods (==) :: Value -> Value -> Bool # (/=) :: Value -> Value -> Bool #
Show Value Source #
Instance details Defined in Data.Configurator.Types Methods showsPrec :: Int -> Value -> ShowS # show :: Value -> String # showList :: [Value] -> ShowS #

type Config = Map Key Value Source #

An evaluated configuation.

Low-level parsing

load :: FilePath -> IO Config Source #

Read and parse a configuration file.

This may cause IO exceptions for reading this file or imported files, and ParseError if there is a problem with parsing or evaluating the file.

newtype ParseError Source #

An error that occurred during the low-level parsing of a configuration file.

Constructors

ParseError Text

Instances

Show ParseError Source #
Instance details Defined in Data.Configurator.Types Methods showsPrec :: Int -> ParseError -> ShowS # show :: ParseError -> String # showList :: [ParseError] -> ShowS #
Exception ParseError Source #
Instance details Defined in Data.Configurator.Types Methods toException :: ParseError -> SomeException # fromException :: SomeException -> Maybe ParseError # displayException :: ParseError -> String #

High-level parsing

data Parser a b Source #

A generic parser.

A Parser a b knows how to extract a b from an a. Typical instances are Parser Value a, which handles the parsing of individual configuration values, and Parser Config a, which handles extracting data from a full keyed configuration file.

Instances

Monad (Parser a) Source #
Instance details Defined in Data.Configurator.Parser Methods (>>=) :: Parser a a0 -> (a0 -> Parser a b) -> Parser a b # (>>) :: Parser a a0 -> Parser a b -> Parser a b # return :: a0 -> Parser a a0 # fail :: String -> Parser a a0 #
Functor (Parser a) Source #
Instance details Defined in Data.Configurator.Parser Methods fmap :: (a0 -> b) -> Parser a a0 -> Parser a b # (<$) :: a0 -> Parser a b -> Parser a a0 #
Applicative (Parser a) Source #
Instance details Defined in Data.Configurator.Parser Methods pure :: a0 -> Parser a a0 # (<>) :: Parser a (a0 -> b) -> Parser a a0 -> Parser a b # liftA2 :: (a0 -> b -> c) -> Parser a a0 -> Parser a b -> Parser a c # (>) :: Parser a a0 -> Parser a b -> Parser a b # (<*) :: Parser a a0 -> Parser a b -> Parser a a0 #

runParser :: Parser a b -> a -> Either Text b Source #

Run a parser.

runParser p x runs the parser p on the input x, returning a value Right v on success, or Left err on error.

Value parsers

bool :: Parser Value Bool Source #

Extract a boolean value.

bool expects the given value to be boolean.

int :: Parser Value Int Source #

Extract an integer value.

int expects the given value to be an Int.

string :: Parser Value Text Source #

Extract a string value.

string expects the given value to be a string.

value :: Parser Value Value Source #

Extract a raw value.

value returns a configuration value in its raw form.

list :: Parser Value a -> Parser Value [a] Source #

Parse a list of values.

list p expects a list value, and parses each entry with p.

Configuration parsers

optional :: Key -> Parser Value a -> Parser Config (Maybe a) Source #

Parse an optional configuration field.

optional key p returns Nothing if the field key is not present. Otherwise it returns Just v, where v is the result of parsing the field value with p.

required :: Key -> Parser Value a -> Parser Config a Source #

Parse a required configuration field.

required key p expects the field key to be present, and parses its value with p.

subassocs :: Key -> Parser Value a -> Parser Config [(Key, a)] Source #

Parse a set of fields with a shared prefix.

subassocs prefix p extracts all configuration keys one level below prefix, and collects pairs of the full keys and the corresponding field values parsed with p.