Matt's post below got me thinking about how I would accomplish the same thing in Ruby, turning an array into a string with each element separated by a comma. Here's what I came up with.

array_of_strings = ["foo", "bar", "foobar"]
str = array_of_strings.collect{|a| a + ", "}.to_s.chop.chop
=> "foo, bar, foobar"

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