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

[ bsd3, json, library ] [ Propose Tags ]

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

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Modules

[Index]

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

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aeson-gadt-th-0.1.2.0.tar.gz [browse] (Cabal source package)
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Maintainer's Corner

Package maintainers

CaleGibbard, JohnEricson, RyanTrinkle, abrar, alexfmpe, maralorn, ymeister

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Candidates

0.1.0.0, 0.1.2.1, 0.2.0.0, 0.2.2, 0.2.3

Versions [RSS]	0.1.0.0, 0.1.1.0, 0.1.2.0, 0.1.2.1, 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, 0.2.5.2 (info)
Dependencies	aeson, aeson-gadt-th, base (>=4.11 && <4.13), dependent-sum (<0.6.2.2), markdown-unlit, template-haskell, transformers [details]
License	BSD-3-Clause
Copyright	2019 Obsidian Systems LLC
Author	Obsidian Systems LLC
Maintainer	maintainer@obsidian.systems
Revised	Revision 2 made by abrar at 2020-10-05T17:56:30Z
Category	JSON
Source repo	head: git clone git://github.com/obsidiansystems/aeson-gadt-th.git
Uploaded	by abrar at 2019-01-25T22:35:24Z
Distributions	NixOS:0.2.5.2
Reverse Dependencies	2 direct, 0 indirect [details]
Executables	readme
Downloads	5236 total (23 in the last 30 days)
Rating	2.0 (votes: 1) [estimated by Bayesian average]
Your Rating	λ λ λ
Status	Docs uploaded by user Build status unknown [no reports yet]

Readme for aeson-gadt-th-0.1.2.0

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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