Toml.FromValue

Use FromValue to define a transformation from some Value to an application domain type.

Use ParseTable to help build FromValue instances that match tables. It will make it easy to track which table keys have been used and which are left over.

Warnings can be emitted using warning and warnTable (depending on what) context you're in. These warnings can provide useful feedback about problematic decodings or keys that might be unused now but were perhaps meaningful in an old version of a configuration file.

Toml.FromValue.Generic can be used to derive instances of FromValue automatically for record types.

Deserialization classes

class FromValue a where

Class for types that can be decoded from a TOML value.

Minimal complete definition

fromValue

Methods

fromValue :: Value -> Matcher a

Convert a Value or report an error message

listFromValue :: Value -> Matcher [a]

Used to implement instance for '[]'. Most implementations rely on the default implementation.

Instances

FromValue Int16

Defined in Toml.FromValue

Methods

fromValue :: Value -> Matcher Int16

listFromValue :: Value -> Matcher [Int16]

FromValue Int32

Defined in Toml.FromValue

Methods

fromValue :: Value -> Matcher Int32

listFromValue :: Value -> Matcher [Int32]

FromValue Int64

Defined in Toml.FromValue

Methods

fromValue :: Value -> Matcher Int64

listFromValue :: Value -> Matcher [Int64]

FromValue Int8

Defined in Toml.FromValue

Methods

fromValue :: Value -> Matcher Int8

listFromValue :: Value -> Matcher [Int8]

FromValue Word16

Defined in Toml.FromValue

Methods

fromValue :: Value -> Matcher Word16

listFromValue :: Value -> Matcher [Word16]

FromValue Word32

Defined in Toml.FromValue

Methods

fromValue :: Value -> Matcher Word32

listFromValue :: Value -> Matcher [Word32]

FromValue Word64

Defined in Toml.FromValue

Methods

fromValue :: Value -> Matcher Word64

listFromValue :: Value -> Matcher [Word64]

FromValue Word8

Defined in Toml.FromValue

Methods

fromValue :: Value -> Matcher Word8

listFromValue :: Value -> Matcher [Word8]

FromValue Text

Matches string literals

Since: 1.2.1.0

Defined in Toml.FromValue

Methods

fromValue :: Value -> Matcher Text

listFromValue :: Value -> Matcher [Text]

FromValue Text

Matches string literals

Since: 1.2.1.0

Defined in Toml.FromValue

Methods

fromValue :: Value -> Matcher Text

listFromValue :: Value -> Matcher [Text]

FromValue Day

Matches local date literals

Defined in Toml.FromValue

Methods

fromValue :: Value -> Matcher Day

listFromValue :: Value -> Matcher [Day]

FromValue LocalTime

Matches local date-time literals

Defined in Toml.FromValue

Methods

fromValue :: Value -> Matcher LocalTime

listFromValue :: Value -> Matcher [LocalTime]

FromValue TimeOfDay

Matches local time literals

Defined in Toml.FromValue

Methods

fromValue :: Value -> Matcher TimeOfDay

listFromValue :: Value -> Matcher [TimeOfDay]

FromValue ZonedTime

Matches offset date-time literals

Defined in Toml.FromValue

Methods

fromValue :: Value -> Matcher ZonedTime

listFromValue :: Value -> Matcher [ZonedTime]

FromValue Value

Matches all values, used for pass-through

Defined in Toml.FromValue

Methods

fromValue :: Value -> Matcher Value

listFromValue :: Value -> Matcher [Value]

FromValue Integer

Matches integer values

Defined in Toml.FromValue

Methods

fromValue :: Value -> Matcher Integer

listFromValue :: Value -> Matcher [Integer]

FromValue Natural

Matches non-negative integer values

Defined in Toml.FromValue

Methods

fromValue :: Value -> Matcher Natural

listFromValue :: Value -> Matcher [Natural]

FromValue Bool

Matches true and false

Defined in Toml.FromValue

Methods

fromValue :: Value -> Matcher Bool

listFromValue :: Value -> Matcher [Bool]

FromValue Char

Matches single-character strings with fromValue and arbitrary strings with listFromValue to support String

Defined in Toml.FromValue

Methods

fromValue :: Value -> Matcher Char

listFromValue :: Value -> Matcher [Char]

FromValue Double

Matches floating-point and integer values

Defined in Toml.FromValue

Methods

fromValue :: Value -> Matcher Double

listFromValue :: Value -> Matcher [Double]

FromValue Float

Matches floating-point and integer values

Defined in Toml.FromValue

Methods

fromValue :: Value -> Matcher Float

listFromValue :: Value -> Matcher [Float]

FromValue Int

Defined in Toml.FromValue

Methods

fromValue :: Value -> Matcher Int

listFromValue :: Value -> Matcher [Int]

FromValue Word

Defined in Toml.FromValue

Methods

fromValue :: Value -> Matcher Word

listFromValue :: Value -> Matcher [Word]

FromValue a => FromValue (NonEmpty a)

Matches non-empty arrays or reports an error.

Since: 1.3.0.0

Defined in Toml.FromValue

Methods

fromValue :: Value -> Matcher (NonEmpty a)

listFromValue :: Value -> Matcher [NonEmpty a]

Integral a => FromValue (Ratio a)

Matches floating-point and integer values.

TOML specifies Floats should be implemented as IEEE 754 binary64 values. so note that the given Rational will be converted from a double representation and will often be an approximation rather than the exact value.

Since: 1.3.0.0

Defined in Toml.FromValue

Methods

fromValue :: Value -> Matcher (Ratio a)

listFromValue :: Value -> Matcher [Ratio a]

FromValue a => FromValue (Seq a)

Matches arrays

Since: 1.3.0.0

Defined in Toml.FromValue

Methods

fromValue :: Value -> Matcher (Seq a)

listFromValue :: Value -> Matcher [Seq a]

(Generic a, GFromArray (Rep a)) => FromValue (GenericTomlArray a)

Instance derived using genericFromArray

Defined in Toml.Generic

Methods

fromValue :: Value -> Matcher (GenericTomlArray a)

listFromValue :: Value -> Matcher [GenericTomlArray a]

(Generic a, GParseTable (Rep a)) => FromValue (GenericTomlTable a)

Instance derived using genericParseTable

Defined in Toml.Generic

Methods

fromValue :: Value -> Matcher (GenericTomlTable a)

listFromValue :: Value -> Matcher [GenericTomlTable a]

FromValue a => FromValue [a]

Implemented in terms of listFromValue

Defined in Toml.FromValue

Methods

fromValue :: Value -> Matcher [a]

listFromValue :: Value -> Matcher [[a]]

(Ord k, FromKey k, FromValue v) => FromValue (Map k v)

Defined in Toml.FromValue

Methods

fromValue :: Value -> Matcher (Map k v)

listFromValue :: Value -> Matcher [Map k v]

class FromKey a where

Convert from a table key

Since: 1.3.0.0

Methods

fromKey :: String -> Matcher a

Instances

FromKey Text

Matches all strings

Since: 1.3.0.0

Defined in Toml.FromValue

Methods

fromKey :: String -> Matcher Text

FromKey Text

Matches all strings

Since: 1.3.0.0

Defined in Toml.FromValue

Methods

fromKey :: String -> Matcher Text

a ~ Char => FromKey [a]

Matches all strings

Since: 1.3.0.0

Defined in Toml.FromValue

Methods

fromKey :: String -> Matcher [a]

Matcher

data Matcher a

Computations that result in a Result and which track a list of nested contexts to assist in generating warnings and error messages.

Use withScope to run a Matcher in a new, nested scope.

Instances

MonadFail Matcher

Fail with an error message annotated to the current location.

Defined in Toml.FromValue.Matcher

Methods

fail :: String -> Matcher a

Alternative Matcher

Defined in Toml.FromValue.Matcher

Methods

empty :: Matcher a

(<|>) :: Matcher a -> Matcher a -> Matcher a

some :: Matcher a -> Matcher [a]

many :: Matcher a -> Matcher [a]

Applicative Matcher

Defined in Toml.FromValue.Matcher

Methods

pure :: a -> Matcher a

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

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

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

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

Functor Matcher

Defined in Toml.FromValue.Matcher

Methods

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

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

Monad Matcher

Defined in Toml.FromValue.Matcher

Methods

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

(>>) :: Matcher a -> Matcher b -> Matcher b

return :: a -> Matcher a

MonadPlus Matcher

Defined in Toml.FromValue.Matcher

Methods

mzero :: Matcher a

mplus :: Matcher a -> Matcher a -> Matcher a

data MatchMessage

A message emitted while matching a TOML value. The message is paired with the path to the value that was in focus when the message was generated. These message get used for both warnings and errors.

Since: 1.3.0.0

Constructors

MatchMessage

Fields

• matchPath :: [Scope]

  path to message location

• matchMessage :: String

  error and warning message body

Instances

Read MatchMessage

Default instance

Defined in Toml.FromValue.Matcher

Methods

readsPrec :: Int -> ReadS MatchMessage

readList :: ReadS [MatchMessage]

readPrec :: ReadPrec MatchMessage

readListPrec :: ReadPrec [MatchMessage]

Show MatchMessage

Default instance

Defined in Toml.FromValue.Matcher

Methods

showsPrec :: Int -> MatchMessage -> ShowS

show :: MatchMessage -> String

showList :: [MatchMessage] -> ShowS

Eq MatchMessage

Default instance

Defined in Toml.FromValue.Matcher

Methods

(==) :: MatchMessage -> MatchMessage -> Bool

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

Ord MatchMessage

Default instance

Defined in Toml.FromValue.Matcher

Methods

compare :: MatchMessage -> MatchMessage -> Ordering

(<) :: MatchMessage -> MatchMessage -> Bool

(<=) :: MatchMessage -> MatchMessage -> Bool

(>) :: MatchMessage -> MatchMessage -> Bool

(>=) :: MatchMessage -> MatchMessage -> Bool

max :: MatchMessage -> MatchMessage -> MatchMessage

min :: MatchMessage -> MatchMessage -> MatchMessage

data Result e a

Computation outcome with error and warning messages. Multiple error messages can occur when multiple alternatives all fail. Resolving any one of the error messages could allow the computation to succeed.

Since: 1.3.0.0

Constructors

Failure [e]

error messages

Success [e] a

warning messages and result

Instances

(Read e, Read a) => Read (Result e a)

Default instance

Defined in Toml.FromValue.Matcher

Methods

readsPrec :: Int -> ReadS (Result e a)

readList :: ReadS [Result e a]

readPrec :: ReadPrec (Result e a)

readListPrec :: ReadPrec [Result e a]

(Show e, Show a) => Show (Result e a)

Default instance

Defined in Toml.FromValue.Matcher

Methods

showsPrec :: Int -> Result e a -> ShowS

show :: Result e a -> String

showList :: [Result e a] -> ShowS

(Eq e, Eq a) => Eq (Result e a)

Default instance

Defined in Toml.FromValue.Matcher

Methods

(==) :: Result e a -> Result e a -> Bool

(/=) :: Result e a -> Result e a -> Bool

(Ord e, Ord a) => Ord (Result e a)

Default instance

Defined in Toml.FromValue.Matcher

Methods

compare :: Result e a -> Result e a -> Ordering

(<) :: Result e a -> Result e a -> Bool

(<=) :: Result e a -> Result e a -> Bool

(>) :: Result e a -> Result e a -> Bool

(>=) :: Result e a -> Result e a -> Bool

max :: Result e a -> Result e a -> Result e a

min :: Result e a -> Result e a -> Result e a

warning :: String -> Matcher ()

Emit a warning mentioning the current scope.

Table matching

data ParseTable a

A Matcher that tracks a current set of unmatched key-value pairs from a table.

Use optKey and reqKey to extract keys.

Use getTable and setTable to override the table and implement other primitives.

Instances

MonadFail ParseTable

Implemented in terms of fail on Matcher

Defined in Toml.FromValue.ParseTable

Methods

fail :: String -> ParseTable a

Alternative ParseTable

Defined in Toml.FromValue.ParseTable

Methods

empty :: ParseTable a

(<|>) :: ParseTable a -> ParseTable a -> ParseTable a

some :: ParseTable a -> ParseTable [a]

many :: ParseTable a -> ParseTable [a]

Applicative ParseTable

Defined in Toml.FromValue.ParseTable

Methods

pure :: a -> ParseTable a

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

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

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

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

Functor ParseTable

Defined in Toml.FromValue.ParseTable

Methods

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

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

Monad ParseTable

Defined in Toml.FromValue.ParseTable

Methods

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

(>>) :: ParseTable a -> ParseTable b -> ParseTable b

return :: a -> ParseTable a

MonadPlus ParseTable

Defined in Toml.FromValue.ParseTable

Methods

mzero :: ParseTable a

mplus :: ParseTable a -> ParseTable a -> ParseTable a

runParseTable :: ParseTable a -> Table -> Matcher a

Run a ParseTable computation with a given starting Table. Unused tables will generate a warning. To change this behavior getTable and setTable can be used to discard or generate error messages.

parseTableFromValue :: ParseTable a -> Value -> Matcher a

Used to derive a fromValue implementation from a ParseTable matcher.

reqKey :: FromValue a => String -> ParseTable a

Convenience function for matching a required key with a FromValue instance.

reqKey key = reqKeyOf key fromValue

optKey :: FromValue a => String -> ParseTable (Maybe a)

Convenience function for matching an optional key with a FromValue instance.

optKey key = optKeyOf key fromValue

reqKeyOf

Arguments

:: String

key

-> (Value -> Matcher a)

value matcher

-> ParseTable a

Match a table entry by key or report an error if missing.

See pickKey for more complex cases.

optKeyOf

Arguments

:: String

key

-> (Value -> Matcher a)

value matcher

-> ParseTable (Maybe a)

Match a table entry by key if it exists or return Nothing if not. If the key is defined, it is matched by the given function.

See pickKey for more complex cases.

warnTable :: String -> ParseTable ()

Emit a warning at the current location.

data KeyAlt a

Key and value matching function

Since: 1.2.0.0

Constructors

Key String (Value -> Matcher a)

pick alternative based on key match

Else (Matcher a)

default case when no previous cases matched

pickKey :: [KeyAlt a] -> ParseTable a

Take the first option from a list of table keys and matcher functions. This operation will commit to the first table key that matches. If the associated matcher fails, only that error will be propagated and the other alternatives will not be matched.

If no keys match, an error message is generated explaining which keys would have been accepted.

This is provided as an alternative to chaining multiple reqKey cases together with (<|>) because that will generate one error message for each unmatched alternative as well as the error associate with the matched alternative.

Since: 1.2.0.0

Table matching primitives

getTable :: ParseTable Table

Return the remaining portion of the table being matched.

setTable :: Table -> ParseTable ()

Replace the remaining portion of the table being matched.

liftMatcher :: Matcher a -> ParseTable a

Lift a matcher into the current table parsing context.