impl Default for RepeatN
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impl Default for RepeatN
#139690
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This creates an empty iterator, like `repeat_n(value, 0)` but without needing any such value at hand. There's precedent in many other iterators that the `Default` is empty, like `slice::Iter`. I found myself wanting this for rayon's `RepeatN` as it lowers to a sequential iterator [here][1]. Since rayon is also optimizing to avoid extra clones, it may end up with parallel splits that have count 0 and no item value. Calling `std::iter::repeat_n(x, 0)` just drops that value, but there's no way to construct the same result without a value yet. This would be straightforward with an empty `Default`. [1]: https://github.com/rayon-rs/rayon/blob/ae07384e3e0b238cea89f0c14891f351c65a5cee/src/iter/repeat.rs#L201-L202
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This creates an empty iterator, like
repeat_n(value, 0)but withoutneeding any such value at hand. There's precedent in many other
iterators that the
Defaultis empty, likeslice::Iter.I found myself wanting this for rayon's
RepeatNas it lowers to asequential iterator here. Since rayon is also optimizing to avoid
extra clones, it may end up with parallel splits that have count 0 and
no item value. Calling
std::iter::repeat_n(x, 0)just drops thatvalue, but there's no way to construct the same result without a value
yet. This would be straightforward with an empty
Default.r? libs-api (insta-stable)