| Copyright | (c) Dong Han 2019 |
|---|---|
| License | BSD |
| Maintainer | winterland1989@gmail.com |
| Stability | experimental |
| Portability | non-portable |
| Safe Haskell | None |
| Language | Haskell2010 |
Z.Data.JSON.Converter
Description
This module provides tools for converting protocol IR (e.g. Value) to Haskell ADTs:
Synopsis
- convert :: (a -> Converter r) -> a -> Either ConvertError r
- data PathElement
- data ConvertError = ConvertError {
- errPath :: [PathElement]
- errMsg :: Text
- newtype Converter a = Converter {
- runConverter :: forall r. ([PathElement] -> Text -> r) -> (a -> r) -> r
- fail' :: Text -> Converter a
- (<?>) :: Converter a -> PathElement -> Converter a
- prependContext :: Text -> Converter a -> Converter a
Documentation
convert :: (a -> Converter r) -> a -> Either ConvertError r Source #
Run a Converter with input value.
data PathElement Source #
Elements of a (JSON) Value path used to describe the location of an error.
Constructors
| Key !Text | Path element of a key into an object, "object.key". |
| Index !Int | Path element of an index into an array, "array[index]". |
| Embedded | path of a embedded (JSON) String |
Instances
data ConvertError Source #
Error info with (JSON) Path info.
Constructors
| ConvertError | |
Fields
| |
Instances
Converter provides a monadic interface to convert protocol IR (e.g.Value) to Haskell ADT.
Constructors
| Converter | |
Fields
| |
(<?>) :: Converter a -> PathElement -> Converter a infixl 9 Source #
Add (JSON) Path context to a converter
When converting a complex structure, it helps to annotate (sub)converters with context, so that if an error occurs, you can find its location.
withFlatMapR "Person" $ \o ->
Person
<$> o .: "name" <?> Key "name"
<*> o .: "age" <?> Key "age"(Standard methods like (.:) already do this.)
With such annotations, if an error occurs, you will get a (JSON) Path location of that error.