Hi, how would I give a list back to a command substitution?

Example:

function blah
    set -l output
    set -a output foo
    set -a output bar
    set -a output baz
    # echo $output[1] <-- prints 'foo' :)
    # echo $output[2] <-- prints 'bar' :)
    # echo $output[3] <-- prints 'baz' :)
    echo $output # <-- prints 'foo bar baz' :)
end

function blargh
    set -l blahOutput (blah)
    echo $blahOutput[2] # :( prints 'foo bar baz', I'd like it to print 'bar'
end