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

• Implement single.shuffle() #59
• Implement single.flip() #60
• Implement single.filterRegEx() #61

Combinatorics

• Implement combinatorics.combinationsWithReplacement() #62

Multi

• Implement multi.unzip() #63

Reduce

• Implement reduce.toRandomValue() #64
• Implement reduce.toNth() #65
• Implement reduce.toFrequencies() #66
• Implement reduce.toString() #67

Summary

• Implement summary.notAllMatch() #68
• Implement summary.isEmpty() #69
• Implement summary.allEqual() #70
• Implement summary.arePermutations() #71
• Implement summary.isPartitioned() #72

Set

• Implement set.difference() #73

Transform

• Implement transform.distribute() #74
• Implement transform.divide() #75

Random

• Implement random.choice() #76
• Implement random.coinFlip() #77
• Implement random.booleans() #78
• Implement random.integers() #79
• Implement random.percentage() #80
• Implement random.rockPaperScissors() #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);