https://github.com/minibill/elm-codec

Build JSON encoders and decoders with minimal boilerplate
https://github.com/minibill/elm-codec

Last synced: about 7 hours ago
JSON representation

Build JSON encoders and decoders with minimal boilerplate

• Host: GitHub
• URL: https://github.com/minibill/elm-codec
• Owner: miniBill
• License: mit
• Created: 2019-05-29T19:42:57.000Z (over 5 years ago)
• Default Branch: main
• Last Pushed: 2024-10-28T15:01:10.000Z (10 days ago)
• Last Synced: 2024-10-28T17:34:34.122Z (10 days ago)
• Language: Elm
• Homepage: https://package.elm-lang.org/packages/miniBill/elm-codec/latest
• Size: 117 KB
• Stars: 44
• Watchers: 5
• Forks: 8
• Open Issues: 2
• Metadata Files:
  • Readme: README.md
  • Changelog: CHANGELOG.md
  • License: LICENSE

Awesome Lists containing this project

README

        
# elm-codecs

This package allows you to build pairs of JSON encoders (`a -> Value`) and decoders (`Decoder a`), collectively called a `Codec a`.

It supports all of the basic types, collections, records and even custom types! See an example at the bottom of this document.

## Design Goals

The design goal is to be as type safe as possible while keeping a nice API.

Using this package will greatly reduce the risk of unmatched encoders and decoders.

The packages re-exposes the `Value` and `Decoder` types from `elm/json`, so you don't need to import them too.

## Learning Resources

Ask for help on the [Elm Slack](https://elmlang.herokuapp.com/).

You can also have a look at the `FAQ.md` file.

## Examples

See the `examples` folder for more examples.

### Basic usage

```elm

import Codec exposing (Codec, Value)

codec : Codec (List Int)

codec =

    Codec.list Codec.int

encode : List Int -> Value

encode list =

    Codec.encoder codec list

decodeString : String -> Result Codec.Error (List Int)

decodeString s =

    Codec.decodeString codec s

```

### Custom types

```elm

type Semaphore

    = Red Int String

    | Yellow

    | Green Float

semaphoreCodec : Codec Semaphore

semaphoreCodec =

    Codec.custom

        (\red yellow green value ->

            case value of

                Red i s ->

                    red i s

                Yellow ->

                    yellow

                Green f ->

                    green f

        )

        |> Codec.variant2 "Red" Red Codec.int Codec.string

        |> Codec.variant0 "Yellow" Yellow

        |> Codec.variant1 "Green" Green Codec.float

        |> Codec.buildCustom

```