Converting a Seq to a list causes RangeError (max call size exceeded)

[phou-patreon]

What happened

Converting a Seq to a list on anything remotely large (even a Seq with 1000 items seems to be enough) causes a max call size exceeded error.

After tracing through the code a bit, it seems to be happening because the implementation of flatDeep is unnecessarily recursive (it iterates recursively in the default case).

How to reproduce

This codesandbox repros the issue: https://codesandbox.io/s/stoic-brook-zlzcs6?file=/src/index.js

[bdurrer]

The documentation and the fact that the sample had to reassign meta = meta.concat(i) suggest that this sample in fact creates 1000 nested sequences, which are lazily linked until toList forces them to materialize.

BTW a better option for bulk operations is withMutation, e.g.

List().withMutations((mutable) => {
  for (let i = 0; i < 10000; ++i) {
    mutable.concat(i);
  }
});

of course, the Seq crashing is bad nonetheless