Transfrom enums for js

1

How can I transform enums to object for js?
For example:

type action = Add(int) | Reset | Divide(float)

I need to convert JS object like:

const action = {
  type: 'Add',
  payload: 10,
}

This needs for redux.

2

Hi @snatvb it sounds like you are using interop with Redux?

Would something like this work for you?

type action = Add(int) | Reset | Divide(float)

external asJson: 'a => Js.Json.t = "%identity"

let toReduxAction = (action: action) =>
  switch action {
  | Add(value) => {"type": "Add", "payload": value}->asJson
  | Reset => {"type": "Reset"}->asJson
  | Divide(value) => {"type": "Divide", "payload": value}->asJson
  }

let reduxAction = toReduxAction(Add(10))
// { type: 'Add', payload: 10 }
2 Likes
4

Hey @kevanstannard, how can I reduce this then?
My reduces contain in ReScript.

5

If your reducer is written in ReScript then you could send a variant as an action.

6

I can’t (look at redux documentation, that action must be an object and contains “type” field)

7

image
image972×1120 335 KB

An exmaple

8

Oh yeah. I have used useReducer and thought redux would also accept actions as any type.

9

https://github.com/a-c-sreedhar-reddy/rescript-redux-react/

type _type = Increment | Decrement | Update(int)
type action = {"type": _type}
let reducer = (~state=1, ~action: action) =>
  switch action["type"] {
  | Increment => state + 1
  | Decrement => state - 1
  | Update(int) => int
  }

Would this work?

10

Thanks, I’ll check and give feedback to you

11

So. I thank that type must be a string, so I did toReduxAction function what transform re-script action to redux action. Where re-script action is payload.

type reduxAction = {
  @as("type") _type: string,
  payload: action,
}
let toReduxAction = action => {_type: "ReReduxAction", payload: action}

But I still think that ReScript should have deriver decorator for configure transformation to JS.
Rust has library – serde for serialization. There is good decision for that.