take non-empty directories in clean-empty-directories-rec

[amtoine]

this is a command introduced in #77.

Note
this is a minor internal question

it basically takes a list of paths to empty directories and removes them and their parents until the parent directories are not empty anymore.
when it's done, the command returns the list of all the deleted empty directories.

i'm wondering if this command should take a list of any kind of file and perform the filtering internally.

# clean all empty directories recursively, starting from a list of target directories
#
# /!\ this command will return sanitized paths /!\
export def clean-empty-directories-up []: list<path> -> list<path> {
    let deleted = unfold $in {|directories|
        let deleted = $directories | each {|it|
            if not ($it | path exists) {
                continue
            }
            if not (ls --all $it | is-empty) {
                continue
            }

            rm --force $it
            $it
        }

        let next = (
            $deleted | each { path dirname | path sanitize } |  where {|it| ls --all $it | is-empty}
        )

        if ($next | is-empty) {
            {out: $deleted}
        } else {
            {out: $deleted, next: $next}
        }
    }

    $deleted | flatten
}