Join values from ruby array but keep their type -

i've got array :

a = [27624,      22,      33,      "ema",      "test",      11,      nil]

when a.join(',') 1 bing string values joined. how can same effect strings retain type. output should :

"27624, 22, 33, 'ema', 'test', 11"

a.map{|e| e.is_a?(string) ? "'#{e}'" : e}.join(',')

alternatively: (this may not have desired effect - particularly nil, other types haven't included here)

a.map(&:inspect).join(',')

Live