aeson-gadt-th: Derivation of Aeson instances for GADTs

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Warnings:

Packages relying on Cabal 1.12 or later should specify a specific version of the Cabal spec of the form 'cabal-version: x.y'. Use 'cabal-version: 2.0'.

Template Haskell for generating ToJSON and FromJSON instances for GADTs. See README.md for examples.

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Properties

Versions	0.1.0.0, 0.1.1.0, 0.1.2.0, 0.1.2.1, 0.2.0.0, 0.2.0.0, 0.2.1.0, 0.2.1.1, 0.2.1.2, 0.2.2, 0.2.3, 0.2.4, 0.2.5.0, 0.2.5.1
Change log	ChangeLog.md
Dependencies	aeson, aeson-gadt-th, base (>=4.8 && <4.13), dependent-sum, template-haskell, transformers [details]
License	BSD-3-Clause
Copyright	2019 Obsidian Systems LLC
Author	Obsidian Systems LLC
Maintainer	maintainer@obsidian.systems
Category	JSON
Source repo	head: git clone git://github.com/obsidiansystems/aeson-gadt-th.git
Uploaded	by abrar at 2019-03-28T21:00:55Z

Modules

Data
- Aeson
  - GADT
    - Data.Aeson.GADT.TH

Downloads

aeson-gadt-th-0.2.0.0.tar.gz [browse] (Cabal source package)
Package description (as included in the package)

Maintainer's Corner

Package maintainers

CaleGibbard, JohnEricson, abrar

For package maintainers and hackage trustees

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Readme for aeson-gadt-th-0.2.0.0

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aeson-gadt-th

Provides Template Haskell expressions for deriving ToJSON and FromJSON instances for GADTs.

Example Usage:

{-# LANGUAGE GADTs #-}
{-# LANGUAGE KindSignatures #-}
{-# LANGUAGE TemplateHaskell #-}
{-# LANGUAGE FlexibleContexts #-}
{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE MultiParamTypeClasses #-}

import Data.Aeson
import Data.Aeson.GADT.TH

data A :: * -> * where
  A_a :: A a
  A_b :: Int -> A ()

data B c :: * -> * where
  B_a :: c -> A a -> B c a
  B_x :: B c x

deriveJSONGADT ''A
deriveJSONGADT ''B

main :: IO ()
main = return ()

Encoding:

encode A_a
> "[\"A_a\",[]]"

Decoding:

When decoding a JSON-encoded GADT, the result will be wrapped using Data.Some.This.

case (decode $ encode A_a) :: Maybe (Some A) of
  Nothing -> error "Couldn't decode
  Just (This A_a) -> putStrLn "it worked"
  Just (This A_b) -> putStrLn "wat"
> it worked