elm-bridge/README.md

Elm Bridge
=====

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## Intro

Hackage: [elm-bridge](http://hackage.haskell.org/package/elm-bridge)

Building the bridge from [Haskell](http://haskell.org) to [Elm](http://elm-lang.org) and back. Define types once, use on both sides and enjoy easy (de)serialisation. Cheers!

This version of the package only supports Elm 0.19. Version 0.5.2 supports Elm 0.18, and Version 0.3.0.2 supports Elm 0.16 and Elm 0.17.

Note that the [bartavelle/json-helpers](http://package.elm-lang.org/packages/bartavelle/json-helpers/latest/) package, with version >= 1.2.0, is expected by the generated Elm modules.

## Usage

```haskell
{-# LANGUAGE TemplateHaskell #-}
import Elm.Derive
import Elm.Module

import Data.Proxy

data Foo
   = Foo
   { f_name :: String
   , f_blablub :: Int
   } deriving (Show, Eq)

deriveBoth defaultOptions ''Foo

main :: IO ()
main =
    putStrLn $ makeElmModule "Foo"
    [ DefineElm (Proxy :: Proxy Foo)
    ]

```

Output will be:

```elm
module Foo where

import Json.Decode
import Json.Decode exposing ((:=))
import Json.Encode
import Json.Helpers exposing (..)


type alias Foo  =
   { f_name: String
   , f_blablub: Int
   }

jsonDecFoo : Json.Decode.Decoder ( Foo )
jsonDecFoo =
   ("f_name" := Json.Decode.string) `Json.Decode.andThen` \pf_name ->
   ("f_blablub" := Json.Decode.int) `Json.Decode.andThen` \pf_blablub ->
   Json.Decode.succeed {f_name = pf_name, f_blablub = pf_blablub}

jsonEncFoo : Foo -> Value
jsonEncFoo  val =
   Json.Encode.object
   [ ("f_name", Json.Encode.string val.f_name)
   , ("f_blablub", Json.Encode.int val.f_blablub)
   ]
```

Also, there are functions `Elm.Json.stringSerForSimpleAdt` and `Elm.Json.stringParserForSimpleAdt` to generate functions for your non-JSON ADT types.

For more usage examples check the tests or the examples dir.

## Install

### Haskell

* Using cabal: `cabal install elm-bridge`
* From Source: `git clone https://github.com/agrafix/elm-bridge.git && cd elm-bridge && cabal install`

### Elm

* `elm package install bartavelle/json-helpers`

or, for Elm 0.19:

* `elm install bartavelle/json-helpers`

## Contribute

Pull requests are welcome! Please consider creating an issue beforehand, so we can discuss what you would like to do. Code should be written in a consistent style throughout the project. Avoid whitespace that is sensible to conflicts. (E.g. alignment of `=` signs in functions definitions) Note that by sending a pull request you agree that your contribution can be released under the BSD3 License as part of the `elm-bridge` package or related packages.