New IterTools Functionality Discussion

[Smoren]

This thread is for discussion new functionality to implement in IterTools. Please reply with suggestions for new functionality.

Here are some of the functions I am considering implementing. Some are more useful than others.

Single

• [ ] #59
• [ ] #60
• [ ] #61

Combinatorics

• [ ] #62

Multi

• [ ] #63

Reduce

• [ ] #64
• [ ] #65
• [ ] #66
• [ ] #67

Summary

• [ ] #68
• [ ] #69
• [ ] #70
• [ ] #71
• [ ] #72

Set

• [ ] #73

Transform

• [ ] #74
• [ ] #75

Random

• [ ] #76
• [ ] #77
• [ ] #78
• [ ] #79
• [ ] #80
• [ ] #81

[zveroboy]

@Smoren First of all, thank you for a wonderful library.

I guess it's pretty hard to implement a FP version of it where functions are curried and parameters are inversed using TS, right?

An example:

const takeWhile = _.curry(function* takeWhile(predicateFn, iterable) {
  for (const item of iterable) {
    if (predicateFn(item)) {
      yield item;
    } else {
      break;
    }
  }
});

const limitAsync = _.curry(async function* limitAsync(count, iterable) {
  if (count < 0) {
    throw new TypeError(`Limit must be ≥ 0. Got ${count}`);
  }

  let i = 0;
  for await (const datum of iterable) {
    if (i >= count) {
      return;
    }
    yield datum;
    ++i;
  }
});

// …
const asyncIterable = httpClient.fetchSomePaginatedDataIterable();

const fetch100ItemsOrLess = _.compose(
  toArrayAsync,
  limitAsync(100),
  flatMapAsync(response => response.data),
);

const result = await fetch100ItemsOrLess(asyncIterable);

[Smoren]

Hi @zveroboy! Thank you for your feedback! I think you can use streams for such tasks.

import { AsyncStream } from 'itertools-ts';

const fetch100ItemsOrLess = async (response) => await AsyncStream.of(response)
  .flatMap(response => response.data)
  .limit(100)
  .toArray();

const result = await fetch100ItemsOrLess(asyncIterable);