@gen-x/list v2.0.0

@gen-x/list

List handling for gen-x

When GenX handles anything iterable, it will yield each individual item through the pipeline. Here's an example when returning or yielding an array from an operator in the pipeline:

import genX from '@gen-x/core'

const iterate = genX(() => [1, 2, 3, 4])

for await (const x of iterate()) {
  console.info(x)
}

// 1
// 2
// 3
// 4

If you want to return a collection of items without it being iterated on, you could use a List, which is a simple, non-iterable, array structure.

import genX from '@gen-x/core'
import * as list from '@gen-x/list'

const iterate = genX(() => list.create(1, 2, 3, 4))

for await (const x of iterate()) {
  console.info(x)
}

// {Symbol(list items): [1, 2, 3, 4]}

There are also utilities for traversing/manipulating a list, which are named the same as Array.prototype functions

• concat
• every
• filter
• find
• findIndex
• forEach
• from
• includes
• indexOf
• join
• keys
• lastIndexOf
• map
• pop
• push
• reduce
• reverse
• shift
• slice
• some
• sort
• splice
• unshift

Apart from being non-iterable, there are a couple of main differences:

1. Lists are immutable. All functions will return a new list.

2. forEach's iteration can be stopped by returning list.Break

   import * as list from '@gen-x/list'
   const l = list.create(1, 2, 3, 4)
   
   list.forEach(l, (x) => {
     if (x >= 3) {
       return list.Break
     }
     console.info(`${x} is less than 3`)
   })
   
   // 1 is less than 3
   // 2 is less than 3

3. There is a list.toArray() function which will return the list as an array

4. You'll need to use the list.get() function to access a property by index:

   import * as list from '@gen-x/list'
   const l = list.create(1, 2, 3, 4)
   console.info(list.get(l, 1))
   // 2