[R] Support dplyr::mutate()

[asfimport]

Reporter: Neal Richardson / @nealrichardson
Assignee: Neal Richardson / @nealrichardson

Related issues:

• [R] Support dplyr verb transmute() (fixes)
• [R] Wire up dplyr::mutate() for datasets (is depended upon by)

PRs and other links:

• GitHub Pull Request #9521

_{Note: This issue was originally created as ARROW-11683. Please see the migration documentation for further details.}

[asfimport]

Neal Richardson / @nealrichardson:
Issue resolved by pull request 9521
#9521