lazily-async

Implements common array methods in a lazy manner. Nothing more.

There's a synchronous version of this library as well, called lazily.
See https://github.com/isotropy/lazily

Installation

``
npm install lazily-async
`

Create a sequence

`javascript
import { Seq } from "lazily-async";

const seq = Seq.of([1, 2, 3])
for await (const i of seq) {
console.log(i)
}
`

It's lazy

Sequences are lazy. For example, in the following example only one map() action is performed irrespective of the length of the sequence.

`javascript
const seq = await Seq.of([1, 2, 3])
.map(async x => x * 2)
.first();
`

toArray()


`javascript
await Seq.of([1, 2, 3])
.toArray()
// [1, 2, 3]
`

map(fn)

`javascript
await Seq.of([1, 2, 3])
.map(async x => x * 2)
.toArray()
// [2, 4, 6]
`

flatMap(fn)

`javascript
await Seq.of([1, 2, 3])
.flatMap(async x => [x10, x20])
.toArray()
// [11, 21, 12, 22, 13, 23]
`

filter(predicate)

`javascript
await Seq.of([1, 2, 3, 4])
.filter(async x => x > 2)
.toArray()
//[3, 4]
`

exit(predicate)

`javascript
await Seq.of([1, 2, 3, 4, 5])
.exit(async x => x > 3)
.toArray()
// [1, 2, 3]
`

exitAfter(predicate)

`javascript
await Seq.of([1, 2, 3, 4, 5])
.exitAfter(async x => x > 3)
.toArray()
// [1, 2, 3, 4]
`

find(predicate)

`javascript
await Seq.of([1, 2, 3, 4, 5])
.find(x => x * 10 === 30)
// 3
`

reduce(fn)

`javascript
await Seq.of([1, 2, 3, 4, 5])
.reduce(async (acc, x) => acc + x, 0)
// 15
`

short-circuited reduce(fn, initialValue, stopPredicate)

`javascript
await Seq.of([1, 2, 3, 4, 5])
.reduce(async (acc, x) => acc + x, 0, async acc => acc > 6)
// 10
`

first()

`javascript
await Seq.of([1, 2, 3, 4, 5])
.first();
// 1
`

first(predicate)

`javascript
await Seq.of([1, 2, 3, 4, 5])
.first(async x => x > 3);
// 4
`

last()

`javascript
await Seq.of([1, 2, 3, 4, 5])
.last();
// 5
`

last(predicate)

`javascript
await Seq.of([1, 2, 3, 4, 5])
.last(async x => x < 3);
// 2
`

every(predicate)

`javascript
await Seq.of([1, 2, 3, 4, 5])
.every(async x => x <= 5);
// true
`

some(predicate)

`javascript
await Seq.of([1, 2, 3, 4, 5])
.some(x => x === 3);
// true
`

includes(item)

`javascript
await Seq.of([1, 2, 3, 4, 5])
.includes(3);
// true
`

concat(seq)

`javascript
await Seq.of([1, 2, 3, 4, 5])
.concat(Seq.of([6, 7, 8)]))
.toArray();
// [1, 2, 3, 4, 5, 6, 7, 8]
`

reverse()

`javascript
await Seq.of([1, 2, 3, 4, 5])
.reverse()
.toArray();
// [5, 4, 3, 2, 1]
`

slice(begin, end)

`javascript
await Seq.of([1, 2, 3, 4, 5])
.slice(2, 4)
.toArray();
// [3, 4, 5]
``