The issue is that [] produces a seq instead of an openarray. I'm pretty sure Araq is aware of those even though it's been a while since the last view/slice/span/range/buffer/iterators discussions see:
* [https://github.com/nim-lang/RFCs/issues/32#issuecomment-373444925](https://github.com/nim-lang/RFCs/issues/32#issuecomment-373444925) * [https://github.com/nim-lang/RFCs/issues/12](https://github.com/nim-lang/RFCs/issues/12) * [https://github.com/nim-lang/RFCs/issues/88](https://github.com/nim-lang/RFCs/issues/88) * [https://github.com/nim-lang/Nim/issues/5437](https://github.com/nim-lang/Nim/issues/5437) * [https://github.com/nim-lang/RFCs/issues/50](https://github.com/nim-lang/RFCs/issues/50) * [https://github.com/nim-lang/RFCs/issues/22](https://github.com/nim-lang/RFCs/issues/22) I guess the sink and lent coming with destructors could help as well to return openarrays in some conservative situations but making openarrays first-class would be the ideal solution in my opinion.
