Add StreamExt::scan #2044
Merged
Add StreamExt::scan #2044
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
taiki-e
reviewed
Jan 20, 2020
cramertj
reviewed
Jan 21, 2020
| /// ``` | ||
| fn scan<S, B, Fut, F>(self, initial_state: S, f: F) -> Scan<Self, S, Fut, F> | ||
| where | ||
| F: FnMut(&mut S, Self::Item) -> Fut, |
There was a problem hiding this comment.
There isn't a way to fix this at the moment, sadly, but this is subtly the wrong method signature for this function, because it doesn't allow Fut to hold onto &mut S. There's no way to fix this right now due to limitations of HRTBs / GATs, so I don't mind accepting this PR now, but note that this makes this API dramatically less useful than it could be otherwise.
|
Thanks for the PR! If you have time to send a PR to add documentation about the restriction I listed above, that'd be perfect, but no worries if not! |
Merged
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
This PR adds combinator similar to https://doc.rust-lang.org/std/iter/trait.Iterator.html#method.scan.
It may be useful for some cases when it's needed to cut stream or transform one stream into another using some state-based computations.