RUBY

ruby array of symbols shorthand

2.4.2 :001 > a = 1
2.4.2 :002 > %i{one two #{a}+three} # Interpolation is ignored
 => [:one, :two, :"#{a}+three"]
2.4.2 :003 > %I{one two #{a}+three} # Interpolation works
 => [:one, :two, :"1+three"]

ruby array of symbols

# Array of symbols
%i[address city state post_code country]
=> [:address, :city, :state, :post_code, :country]

# Array of strings
 %w[address city state postal country]
=> ["address", "city", "state", "postal", "country"]

# Array of interpolated symbols
postal_label = 'zip'
%I[address city state #{postal_label} country]
=> [:address, :city, :state, :zip, :country]

# Array of interpolated strings
%W[address city state #{postal_label} country]
=> ["address", "city", "state", "zip", "country"]
# Instead of %i[] you may use %i{} or %i() or %i!!