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How to elegantly flatten a list

YCM Jason on October 04, 2017

The problem Given any list xs, where xs could contain other lists or any non-list values, we wish to extract all the values in xs. For e...
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Marko Taponen •

In order to understand recursion one must understand recursion.

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YCM Jason •

my favourite quote of all time!

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Sebastian Rapetti • • Edited

Hi!
PHP do not have native functions for flatten.
Link below, my php functions:
gist.github.com/s3b4stian/0e2e638a...

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Maroun Baydoun • • Edited

What do you think about my solution? Flatten an array in JavaScript

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YCM Jason • • Edited

It is interesting! There are a few points about your solution:

  1. checking array should be done with Array.isArray() (here)
  2. I think it would be better if you take the base case outside your reducer function.

If I were going to define flatten with reduce, I would have written something like the following:

function flatten(xs){
  if(xs.length === 0) return [];
  return xs.reduce((acc, x) => [...acc, ...(Array.isArray(x)? flatten(x):
 [x])], []);
}