xrange
Python-esque iterator for number ranges
`xrange` is a function based on Python 3's [`range`](https://docs.python.org/3/library/stdtypes.html?highlight=range#ranges) class (or Python 2's [`xrange`](https://docs.python.org/2.7/library/functions.html#xrange) class). Like the one in Python, `xrange` creates virtual arrays (see [Iterators](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Iteration_protocols)) which allows getting values lazily. This prevents over-the-top memory consumption when using large numbers, and opens the possibility to create never-ending, infinite lists.
Created with create-package-typescript
## [Examples](https://github.com/parzh/xrange/tree/main/docs/examples)
Simple iteration:
```ts
for (const number of xrange(5))
console.log(number); // 0, 1, 2, 3, 4
```
#### Creation of arrays:
```ts
[ ...xrange(5) ];
// [ 0, 1, 2, 3, 4 ]
```
#### Infinite and backward iteration:
```ts
xrange(0, Infinity);
// 0, 1, 2, 3, … (never ends)
```
```ts
xrange(10, 0, -1);
// 10, 9, 8, 7, 6, 5, 4, 3, 2, 1
```
#### Complex number sequences:
```ts
xrange(1, (next) => next < 100, ([ last, prelast = 0 ]) => last + prelast);
// 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89
```
```ts
xrange(0, () => true, ([ last ]) => last ? 0 : 1);
// 0, 1, 0, 1, 0, 1, … (never ends)
```
#### Iteration with methods (see [#14](https://github.com/parzh/xrange/issues/14)):
```ts
xrange(17, 42, 5).forEach(number => {
console.log(number); // 17, 22, 27, 32, 37
});
```
> See more in [/docs/examples](https://github.com/parzh/xrange/tree/main/docs/examples)
## `range` vs `xrange`
> Looking for less functionality in a smaller bundle? Check out [`@xrange/core`](https://npmjs.org/package/@xrange/core) and [`@xrange/func`](https://npmjs.org/package/@xrange/func)
The main difference of `xrange` from [`range`](https://npmjs.org/package/range) is that `xrange` is an iterator, not an array constructor, — it yields numbers on demand, leaving array creation decision to user, which can always be done using the [`...` spread operator](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Spread_syntax) or [`Array.from`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/from).
While also having a larger bundle, `xrange` delegates the actual iteration to [`@xrange/core`](https://npmjs.org/package/@xrange/core), which is vastly smaller, and can be used on its own (in some cases the usage is different though).
While `@xrange/core` provides numeric iterator, [`@xrange/func`](https://npmjs.org/package/@xrange/func) implements predicated iteration, provided as a separate smaller package. It also has less error correction, but the functionality is quite similar to `xrange`, since `xrange` uses `@xrange/func` under the hood.