IterStar

Iter* is a simple lib for providing methods to iterate over array like objects in a generator fashion.

It offers a few similar methods as normal arrays, but may have a few limitations due to logic. The Iter class is a bit slower than a traditional array, but allows you to work with data sets that are a lot larger than an array can be.

If the method on a Iter returns another Iter then it won't actually execute the function provided in unless you call something like .collect() or wait() to force it to iterate through everything. .wait() works just like .collect() except it does not store the returned values. It is meant to be used in instances where you want all the functions to execute but don't want a returned array. This helps if the amount you're trying to iterate through is larger than a normal array can be.

let array = new Iter([0, 1, 2, 3, 4, 5])
  .map((x) => x + Math.floor(Math.random() * 10))
  .collect();

array = new Iter(range(5, 10))
  .filter((x) => x % 2)
  .collect();

const array = await new AsyncIter(await asyncRange(5, 10))
  .filter((x) => x % 2)
  .collect();

Examples

Processing a zipped csv file

import { CsvParseStream } from 'https://deno.land/std/csv/mod.ts'
import { AsyncIter } from 'https://deno.land/x/iterstar/mod.ts'
import { read } from 'https://deno.land/x/streaming_zip/read.ts'

const iter: AsyncIter<string[]> = new AsyncIter(read((await fetch('URL')).body!))
  .filter<{ type: 'file' }>(entry => entry.type === 'file')
  .map(entry => entry.body.stream().pipeThrough(new TextDecoderStream()).pipeThrough(new CsvParseStream()))
  .flat()

const keys: string[] = (await iter.shift())!
iter
  .map(values => values.reduce((obj, value, i) => (obj[keys[i]] = value, obj), {} as Record<string, string>))
  .forEach(row => console.log(row))