concatenate_datasets for iterable datasets
CONTRIBUTOR
It is probably worth noting here that the [documentation](https://huggingface.co/docs/datasets/process#concatenate) is misleading (indicating that it does work for IterableDatasets):

> You can also mix several datasets together by taking alternating examples from each one to create a new dataset. This is known as interleaving, and you can use it with [interleave_datasets()](https://huggingface.co/docs/datasets/v2.2.1/en/package_reference/main_classes#datasets.interleave_datasets). **Both [interleave_datasets()](https://huggingface.co/docs/datasets/v2.2.1/en/package_reference/main_classes#datasets.interleave_datasets) and [concatenate_datasets()](https://huggingface.co/docs/datasets/v2.2.1/en/package_reference/main_classes#datasets.concatenate_datasets) will work with regular [Dataset](https://huggingface.co/docs/datasets/v2.2.1/en/package_reference/main_classes#datasets.Dataset) and [IterableDataset](https://huggingface.co/docs/datasets/v2.2.1/en/package_reference/main_classes#datasets.IterableDataset) objects**. Refer to the [Stream](https://huggingface.co/docs/datasets/stream#interleave) section for an example of how it’s used. 
2022-05-15T12:33:18Z
https://github.com/huggingface/datasets/issues/2564#issuecomment-1126929387
https://api.github.com/repos/huggingface/datasets/issues/2564
IC_kwDODunzps5DK5Pr
https://api.github.com/repos/huggingface/datasets/issues/comments/1126929387/reactions
2022-05-15T12:33:18Z
https://api.github.com/repos/huggingface/datasets/issues/comments/1126929387
https://avatars.githubusercontent.com/u/23721977?v=4
https://api.github.com/users/KennethEnevoldsen/events{/privacy}
https://api.github.com/users/KennethEnevoldsen/followers
https://api.github.com/users/KennethEnevoldsen/following{/other_user}
https://api.github.com/users/KennethEnevoldsen/gists{/gist_id}
https://github.com/KennethEnevoldsen
KennethEnevoldsen
MDQ6VXNlcjIzNzIxOTc3
https://api.github.com/users/KennethEnevoldsen/orgs
https://api.github.com/users/KennethEnevoldsen/received_events
https://api.github.com/users/KennethEnevoldsen/repos
https://api.github.com/users/KennethEnevoldsen/starred{/owner}{/repo}
https://api.github.com/users/KennethEnevoldsen/subscriptions
User
https://api.github.com/users/KennethEnevoldsen
public
MEMBER
Thanks for the heads up, I'll fix that
2022-05-16T16:19:57Z
https://github.com/huggingface/datasets/issues/2564#issuecomment-1127873372
https://api.github.com/repos/huggingface/datasets/issues/2564
IC_kwDODunzps5DOftc
https://api.github.com/repos/huggingface/datasets/issues/comments/1127873372/reactions
2022-05-16T16:19:57Z
https://api.github.com/repos/huggingface/datasets/issues/comments/1127873372
https://avatars.githubusercontent.com/u/42851186?v=4
https://api.github.com/users/lhoestq/events{/privacy}
https://api.github.com/users/lhoestq/followers
https://api.github.com/users/lhoestq/following{/other_user}
https://api.github.com/users/lhoestq/gists{/gist_id}
https://github.com/lhoestq
lhoestq
MDQ6VXNlcjQyODUxMTg2
https://api.github.com/users/lhoestq/orgs
https://api.github.com/users/lhoestq/received_events
https://api.github.com/users/lhoestq/repos
https://api.github.com/users/lhoestq/starred{/owner}{/repo}
https://api.github.com/users/lhoestq/subscriptions
User
https://api.github.com/users/lhoestq
public
Currently `concatenate_datasets` only works for map-style `Dataset`.

It would be nice to have it work for `IterableDataset` objects as well.

It would simply chain the iterables of the iterable datasets.