@greenlabs/ppx-spice

Spice

A ReScript PPX, which generates the (polymorphic) variant (de)serializer.

Spice is originated from

• The Spice melange in the novel, Dune
• A flavor for the (polymorphic) variant

This PPX is highly influenced by Decco and developed with forking the source codes of Decco.

Motivation

• Parse the string instead of the array

To parse the JSON data, Decco is heavily used in the projects. There's a restriction to parse the JSON string into a variant. With the Decco, the data should be formed in an array. It is obvious at some point. But generally, we face the string data which needs to be parsed into the variant in most use cases.

• Parse/stringify the Unicode string

There are many cases to parse and stringify the string data against (polymorphic) variants. Furthermore, the Unicode string needs to be handled with a variant. Currently, pattern matching is not working for the Unicode string in ReScript, the Spice is using if ... then ... else to compare the Unicode string.

Example

@spice
type t = | @spice.as(`하나`) One | @spice.as(`second`) Two

// automatically generated
let t_encode = ...

// automatically generated
let t_decode = ...

let encoded = One->t_encode // `하나`

let decoded = `second`->t_decode // Belt.Result.Ok(Two)

Install

yarn add -D @greenlabs/ppx-spice

// bsconfig.json
"ppx-flags": [
  ...,
  "@greenlabs/ppx-spice/ppx"
],

Development

• Install dependencies

cd src
esy install

• Build

(make sure in /src directory)
esy build

• Test

cd test

(install dependencies)
yarn

(build --watch)
yarn res:clean && yarn res:watch

(run test --watch)
yarn test:watch