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Update promise docs #409

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30 changes: 25 additions & 5 deletions pages/docs/manual/latest/promise.mdx
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Expand Up @@ -8,9 +8,31 @@ canonical: "/docs/manual/latest/promise"

ReScript's primary mechanism for async programming is the same as JavaScript's (callbacks and promises), since we compile cleanly to JavaScript and would like to avoid dragging in a heavy custom runtime.

However, it is planned for us to introduce a coroutine-like feature in the future; for that reason, we're postponing introducing the keywords `async` and `await` into the language; though our (upcoming) Promise API bindings revamp + [pipe](pipe) will make your async code already look better than otherwise.
There is currently no support for `async` and `await` keywords in ReScript; though our new Promise API bindings revamp + [pipe](pipe) will make your async code already look better than otherwise.

## Promise
## Promise (new)

Our up to date Promise bindings are currently not part of the the standard library. For now, please install them separately:

```sh
npm install @ryyppy/rescript-promise --save
```

In your `bsconfig.json`:

```json
{
"bs-dependencies": ["@ryyppy/rescript-promise"]
}
```

_Alternatively you may vendor the [`Promise.res` / `Promise.resi` files](https://github.com/ryyppy/rescript-promise/tree/master/src) files in your app codebase if you want to have more control._

You can find the APIs and full usage examples [here](https://github.com/ryyppy/rescript-promise#usage).

## Promise (legacy)

> **Note:** The `Js.Promise` bindings are following the outdated data-last convention from a few years ago. We kept those APIs for backwards compatibility, so for now please use [`rescript-promise`](https://github.com/ryyppy/rescript-promise) until we upstream the new bindings to our standard library.

ReScript has built-in support for [JavaScript promises](api/js/promise). The 3 functions you generally need are:

Expand All @@ -32,7 +54,7 @@ Js.Promise.make: (
This type signature means that `make` takes a callback that takes 2 named arguments, `resolve` and `reject`. Both arguments are themselves [uncurried callbacks](
function.md#uncurried-function) (with a dot). `make` returns the created promise.

## Usage
### Usage

Using the [pipe operator](pipe.md):

Expand Down Expand Up @@ -73,5 +95,3 @@ myPromise
```

</CodeTab>