Copyright	(c) Eric Mertens 2023
License	ISC
Maintainer	emertens@gmail.com
Safe Haskell	Safe-Inferred
Language	Haskell2010

Toml.FromValue.Matcher

Description

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.

Synopsis

data Matcher a
data Result a
- = Failure [String]
- | Success [String] a
runMatcher :: Matcher a -> Result a
withScope :: String -> Matcher a -> Matcher a
getScope :: Matcher [String]
warning :: String -> Matcher ()

Documentation

data Matcher a Source #

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

Instances details

MonadFail Matcher Source #	Fail with an error message annotated to the current location.
Instance details Defined in Toml.FromValue.Matcher Methods fail :: String -> Matcher a #
Alternative Matcher Source #
Instance details 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 Source #
Instance details 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 Source #
Instance details Defined in Toml.FromValue.Matcher Methods fmap :: (a -> b) -> Matcher a -> Matcher b # (<$) :: a -> Matcher b -> Matcher a #
Monad Matcher Source #
Instance details 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 Source #
Instance details Defined in Toml.FromValue.Matcher Methods mzero :: Matcher a # mplus :: Matcher a -> Matcher a -> Matcher a #

data Result a Source #

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.

Constructors

Failure [String]
Success [String] a

Instances

Instances details

Read a => Read (Result a) Source #
Instance details Defined in Toml.FromValue.Matcher Methods readsPrec :: Int -> ReadS (Result a) # readList :: ReadS [Result a] # readPrec :: ReadPrec (Result a) # readListPrec :: ReadPrec [Result a] #
Show a => Show (Result a) Source #
Instance details Defined in Toml.FromValue.Matcher Methods showsPrec :: Int -> Result a -> ShowS # show :: Result a -> String # showList :: [Result a] -> ShowS #
Eq a => Eq (Result a) Source #
Instance details Defined in Toml.FromValue.Matcher Methods (==) :: Result a -> Result a -> Bool # (/=) :: Result a -> Result a -> Bool #
Ord a => Ord (Result a) Source #
Instance details Defined in Toml.FromValue.Matcher Methods compare :: Result a -> Result a -> Ordering # (<) :: Result a -> Result a -> Bool # (<=) :: Result a -> Result a -> Bool # (>) :: Result a -> Result a -> Bool # (>=) :: Result a -> Result a -> Bool # max :: Result a -> Result a -> Result a # min :: Result a -> Result a -> Result a #

runMatcher :: Matcher a -> Result a Source #

Run a Matcher with an empty scope.

withScope :: String -> Matcher a -> Matcher a Source #

Run a Matcher with a locally extended scope.

getScope :: Matcher [String] Source #

Get the current list of scopes.

warning :: String -> Matcher () Source #

Emit a warning mentioning the current scope.