readme.js

November 7, 2018 · View on GitHub

/**

callbag-pipe
Utility function for plugging callbags together in chain. This utility
actually doesn't rely on Callbag specifics, and is really similar to
Ramda's pipe or lodash's flow.
Implementation of callbag-pipe using R.pipe could look like this:
const pipe = (source, ...cbs) => R.pipe(...cbs)(source)
This exists to play nicely with the ecosystem,
and to facilitate the import of the function.
npm install callbag-pipe
Example:
Create a source with pipe, then pass it to a forEach:

const interval = require('callbag-interval');

const forEach = require('callbag-for-each');

const combine = require('callbag-combine');

```
const pipe = require('callbag-pipe');
```
```
const take = require('callbag-take');
```
```
const map = require('callbag-map');
```
```
const source = pipe(
```

  combine(interval(100), interval(350)),

```
  map(([x, y]) => `X${x},Y${y}`),
```
```
  take(10)
```
```
);
```

forEach(x => console.log(x))(source); // X2,Y0

                                      // X3,Y0

                                      // X4,Y0

                                      // X5,Y0

                                      // X6,Y0

                                      // X6,Y1

                                      // X7,Y1

                                      // X8,Y1

                                      // X9,Y1

                                      // X9,Y2

Or use pipe to go all the way from source to sink:

const interval = require('callbag-interval');

const forEach = require('callbag-for-each');

const combine = require('callbag-combine');

```
const pipe = require('callbag-pipe');
```
```
const take = require('callbag-take');
```
```
const map = require('callbag-map');
```
```
pipe(
```

  combine(interval(100), interval(350)),

```
  map(([x, y]) => `X${x},Y${y}`),
```
```
  take(10),
```
```
  forEach(x => console.log(x))
```
```
);
```
```
// X2,Y0
```
```
// X3,Y0
```
```
// X4,Y0
```
```
// X5,Y0
```
```
// X6,Y0
```
```
// X6,Y1
```
```
// X7,Y1
```
```
// X8,Y1
```
```
// X9,Y1
```
```
// X9,Y2
```
Nesting
To use pipe inside another pipe, you need to give the inner pipe an
argument, e.g. s => pipe(s, ...:

const interval = require('callbag-interval');

const forEach = require('callbag-for-each');

const combine = require('callbag-combine');

```
const pipe = require('callbag-pipe');
```
```
const take = require('callbag-take');
```
```
const map = require('callbag-map');
```
```
pipe(
```

  combine(interval(100), interval(350)),

```
  s => pipe(s,
```
```
    map(([x, y]) => `X${x},Y${y}`),
```
```
    take(10)
```
```
  ),
```
```
  forEach(x => console.log(x))
```
```
);
```
This means you can use pipe to create a new operator:
```
const mapThenTake = (f, amount) =>
```
```
  s => pipe(s, map(f), take(amount));
```
```
pipe(
```

  combine(interval(100), interval(350)),

  mapThenTake(([x, y]) => `X${x},Y${y}`, 10),

```
  forEach(x => console.log(x))
```
```
);
```

*/

function pipe(...cbs) { let res = cbs[0]; for (let i = 1, n = cbs.length; i < n; i++) res = cbsi; return res; }

module.exports = pipe;