Toml.FromValue.Matcher

This type helps to build up computations that can validate a TOML value and compute some application-specific representation.

It supports warning messages which can be used to deprecate old configuration options and to detect unused table keys.

It supports tracking multiple error messages when you have more than one decoding option and all of them have failed.

Use prettyMatchMessage for an easy way to make human readable strings from matcher outputs.

Types

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 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

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

Operations

runMatcher :: Matcher a -> Result MatchMessage a

Run a Matcher with an empty scope.

Since: 1.3.0.0

withScope :: Scope -> Matcher a -> Matcher a

Run a Matcher with a locally extended scope.

Since: 1.3.0.0

getScope :: Matcher [Scope]

Get the current list of scopes.

Since: 1.3.0.0

warning :: String -> Matcher ()

Emit a warning mentioning the current scope.

Scope helpers

data Scope

Scopes for TOML message.

Since: 1.3.0.0

Constructors

ScopeIndex Int

zero-based array index

ScopeKey String

key in a table

Instances

Read Scope

Default instance

Defined in Toml.FromValue.Matcher

Methods

readsPrec :: Int -> ReadS Scope

readList :: ReadS [Scope]

readPrec :: ReadPrec Scope

readListPrec :: ReadPrec [Scope]

Show Scope

Default instance

Defined in Toml.FromValue.Matcher

Methods

showsPrec :: Int -> Scope -> ShowS

show :: Scope -> String

showList :: [Scope] -> ShowS

Eq Scope

Default instance

Defined in Toml.FromValue.Matcher

Methods

(==) :: Scope -> Scope -> Bool

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

Ord Scope

Default instance

Defined in Toml.FromValue.Matcher

Methods

compare :: Scope -> Scope -> Ordering

(<) :: Scope -> Scope -> Bool

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

(>) :: Scope -> Scope -> Bool

(>=) :: Scope -> Scope -> Bool

max :: Scope -> Scope -> Scope

min :: Scope -> Scope -> Scope

inKey :: String -> Matcher a -> Matcher a

Update the scope with the message corresponding to a table key

Since: 1.3.0.0

inIndex :: Int -> Matcher a -> Matcher a

Update the scope with the message corresponding to an array index

Since: 1.3.0.0