Language.Libconfig.Encode

Converting from Language.Libconfig.Types structures to native libconfig Configurations.

Documentation

To run these usage examples, you must tell GHC it's allowed to parse string literals as Text values:

>>> :set -XOverloadedStrings

We also pre-define the test Group to be the example from the libconfig manual.

>>> let Just [version, application, window, title, size, w, h, pos, x, y, list, books, author, price, qty, misc, pi, columns, bigint, bitmask] = mapM textToName ["version", "application", "window", "title", "size", "w", "h", "pos", "x", "y", "list", "books", "author", "price", "qty", "misc", "pi", "columns", "bigint", "bitmask"]
>>> let test = [version := Scalar (String "1.0"),application := Group [window := Group [title := Scalar (String "My Application"),size := Group [w := Scalar (Integer 640),h := Scalar (Integer 480)],pos := Group [x := Scalar (Integer 350),y := Scalar (Integer 250)]],list := List [List [Scalar (String "abc"),Scalar (Integer 123),Scalar (Boolean True)],Scalar (Float 1.234),List []],books := List [Group [title := Scalar (String "Treasure Island"),author := Scalar (String "Robert Louis Stevenson"),price := Scalar (Float 29.95),qty := Scalar (Integer 5)],Group [title := Scalar (String "Snow Crash"),author := Scalar (String "Neal Stephenson"),price := Scalar (Float 9.99),qty := Scalar (Integer 8)]],misc := Group [pi := Scalar (Float 3.141592654),bigint := Scalar (Integer64 9223372036854775807),columns := Array [String "Last Name",String "First Name",String "MI"],bitmask := Scalar (Hex 8131)]]]

Encoding libconfig native data

encode :: Group -> IO (Either EncodeError Configuration)

Convert a top-level Group of Settings into a native Configuration. This allocates a new Configuration.

>>> Right conf <- encode test
>>> C.configWriteFile conf "/tmp/encode_output_test.conf"
Just ()

>>> Just newconf <- C.configNew "/tmp/encode_output_test.conf"

encodeAt :: Configuration -> Group -> IO (Either EncodeError ())

Encode a top-level Group of Settings and write them to the specified Configuration.

encodeValue :: Setting -> Value -> IO (Either EncodeError ())

Set the value of the given Setting to the provided Value (recursively). If this Setting is of a collection type, any pre-existing children will be removed.

encodeTo :: Group -> String -> IO (Either EncodeError ())

Convert a top-level Group of Settings into a native libconfig structure and output it to the specified file path.

>>> encodeTo test "/tmp/encode_output_test_2.conf"
Right ()

>>> Just newconf <- C.configNew "/tmp/encode_output_test_2.conf"

Encoding errors

data EncodeError

Any of these problems can occur while encoding a libconfig Configuration.

Constructors

EncoderRoot

No root setting was found (possibly this configuration is invalid?)

TypeMismatch

Fields

encodeErrSetting :: Text

The Haskell structure contained invalid libconfig types for this setting.

FileOutput

Fields

encodeErrFilename :: Text

Failed to open this file

AddSetting

Fields

encodeErrParent :: Text

Failed to create a new Setting

encodeErrValue :: Value

This was the value we were making a spot for

RemoveOldValue

Fields

encodeErrSetting :: Text

The Haskell structure contained invalid libconfig types for this setting.

SetValue

Fields

encodeErrSetting :: Text

The Haskell structure contained invalid libconfig types for this setting.

encodeErrValue :: Value

This was the value we were making a spot for

SetIndex

Fields

encodeErrParent :: Text

Failed to create a new Setting

encodeErrIndex :: Int

This is the index of the element

encodeErrValue :: Value

This was the value we were making a spot for

Instances

Eq EncodeError

Data EncodeError

Ord EncodeError

Read EncodeError

Show EncodeError

Generic EncodeError

NFData EncodeError

Typeable * EncodeError

type Rep EncodeError

Helpers

valueType :: Value -> ConfigType

Compute the ConfigType of a Value

>>> valueType (Scalar (String "butts"))
StringType

>>> valueType (Array [String "butts"])
ArrayType

scalarType :: Scalar -> ConfigType

Compute the ConfigType of a Scalar

>>> scalarType (String "butts")
StringType

>>> scalarType (Boolean False)
BoolType