test.rb

require 'benchmark/ips'
require 'securerandom'

test = (0..50).map{ SecureRandom.hex }

Benchmark.ips do |b|
  b.report("map") do |i|
    while i > 0
      test.map{|x| -x}
      i -= 1
    end
  end
  b.report("colon") do |i|
    while i > 0
      test.map(&:-@)
      i -= 1
    end
  end
end


# Ruby 2.5.1
# Warming up --------------------------------------
#                  map     9.729k i/100ms
#                colon    11.385k i/100ms
# Calculating -------------------------------------
#                  map    103.892k (± 4.1%) i/s -    525.366k in   5.065502s
#                colon    122.142k (± 3.8%) i/s -    614.790k in   5.040780s