Callbag-to-awaitable NPM | npm.io

1.0.0 • Published 8 years ago

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8 years ago

/**

callbag-to-awaitable
Use the async/await syntax with pullable Callbags! There are actually no
Promises in this package, just async-await syntax on objects with a then
method.
npm install callbag-to-awaitable
Example: on an async pullable callbag source, apply some operators, then
convert to an awaitable and consume it in an async/await function:

const {forEach, take, map, pipe} = require('callbag-basics');

const toAwaitable = require('callbag-to-awaitable');

function pullableAsyncSource(start, sink) {

```
  if (start !== 0) return;
```
```
  let i = 0;
```
```
  sink(0, t => {
```
```
    if (t === 1) {
```

      setTimeout(() => { sink(1, i++) }, 1000);

```
    }
```
```
  });
```
```
}
```
```
const source = pipe(
```

  pullableAsyncSource, // 0, 1, 2, 3, 4, 5, 6, 7...

```
  take(5), // 0, 1, 2, 3, 4
```

  map(x => x / 4) // 0, 0.25, 0.5, 0.75, 1

```
);
```
```
async function main() {
```
```
  const next = toAwaitable(source);
```
```
  try {
```
```
    while (true) {
```
```
      const x = await next;
```
```
      console.log(x);
```
```
    }
```
```
  } catch (end) {
```
```
    console.log('done');
```
```
  }
```
```
}
```
```
main()
```
```
// 0
```
```
// 0.25
```
```
// 0.5
```
```
// 0.75
```
```
// 1
```
```
// done
```
For more inquiries, read or fork the source below: */

function toAwaitable(source) { let talkback; let resolve; let reject; let reason = false; source(0, (t, d) => { if (t === 0) talkback = d; if (t === 1 && resolve) resolve(d); if (t === 2) { reason = d || true; if (reject) reject(reason); } resolve = void 0; reject = void 0; }); return { then: (_resolve, _reject) => { if (reason) _reject(reason); resolve = _resolve; reject = _reject; if (talkback) talkback(1); }, }; }

module.exports = toAwaitable;

@everything-registry/sub-chunk-1288

8 years ago