Symbol#to_proc's hot cousin. Simple and elegant alternative to using &:method with enumerables. compare: enum = [1.4, 2.4 ,3.4] enum.map {|i| i.floor } #=> [1, 2, 3] enum.map(&:floor) #=> [1, 2, 3] enum.every.floor #=> [1, 2, 3] arguments? sure: %w( axb dxf ).every.gsub(/x/,'y') #=> ['ayb', 'dyf'] %w( axb dxf ).every.gsub(/x/) { 'y' } #=> ['ayb', 'dyf']