Преобразование массива Ruby в строку

> a = ['12','34','35','231']
> a.map { |i| "'" + i.to_s + "'" }.join(",")
=> "'12','34','35','231'"

> puts "'"+['12','34','35','231']*"','"+"'"
'12','34','35','231'

> puts ['12','34','35','231'].inspect[1...-1].gsub('"',"'")
'12', '34', '35', '231'

array.inspect.inspect.gsub (/ \ [| \] /, "") может помочь

И еще один вариант

a = ['12','34','35','231']
a.to_s.gsub(/\"/, '\'').gsub(/[\[\]]/, '')

irb(main):027:0> puts ['12','34','35','231'].inspect.to_s[1..-2].gsub('"', "'")
'12', '34', '35', '231'
=> nil

irb(main)> varA
=> {0=>["12", "34", "35", "231"]}
irb(main)> varA = Hash[*ex.collect{|a,b| [a,b.join(",")]}.flatten]
...