sum_bench.rb

require 'benchmark/ips'

module Enumerable
  def old_sum(identity = 0, &block)
    if block_given?
      map(&block).old_sum(identity)
    else
      inject { |sum, element| sum + element } || identity
    end
  end

  def new_sum(identity = 0, &block)
    if block_given?
      map(&block).new_sum(identity)
    else
      inject(:+) || identity
    end
  end
end

summable = (1..100).to_a # sum is 5050
alphabetable = ("a".."z").to_a # sum is the alphabet

Benchmark.ips do |x|
  x.report("old_sum") { summable.old_sum }
  x.report("new_sum") { summable.new_sum }
  x.compare!
end

# Calculating -------------------------------------
#              old_sum    10.674k i/100ms
#              new_sum    14.542k i/100ms
# -------------------------------------------------
#              old_sum    117.350k (± 7.1%) i/s -    587.070k
#              new_sum    154.712k (± 3.8%) i/s -    785.268k
#
# Comparison:
#              new_sum:   154712.1 i/s
#              old_sum:   117350.0 i/s - 1.32x slower

Benchmark.ips do |x|
  x.report("old_sum string") { alphabetable.old_sum }
  x.report("new_sum string") { alphabetable.new_sum }
  x.compare!
end

# Calculating -------------------------------------
#       old_sum string    16.197k i/100ms
#       new_sum string    16.489k i/100ms
# -------------------------------------------------
#       old_sum string    175.858k (±12.7%) i/s -    874.638k
#       new_sum string    207.072k (±14.4%) i/s -      1.022M
#
# Comparison:
#       new_sum string:   207072.2 i/s
#       old_sum string:   175857.9 i/s - 1.18x slower

Benchmark.ips do |x|
  x.report("old_sum with block") { summable.old_sum { |i| i * 2 } }
  x.report("new_sum with block") { summable.new_sum { |i| i * 2 } }
  x.compare!
end

# Calculating -------------------------------------
#   old_sum with block     5.315k i/100ms
#   new_sum with block     5.984k i/100ms
# -------------------------------------------------
#   old_sum with block     54.726k (± 7.5%) i/s -    276.380k
#   new_sum with block     60.620k (± 6.8%) i/s -    305.184k
#
# Comparison:
#   new_sum with block:    60620.2 i/s
#   old_sum with block:    54726.2 i/s - 1.11x slower

Benchmark.ips do |x|
  x.report("old_sum string with block") { alphabetable.old_sum { |i| i * 2 } }
  x.report("new_sum string with block") { alphabetable.new_sum { |i| i * 2 } }
  x.compare!
end

# Calculating -------------------------------------
# old_sum string with block
#                          6.604k i/100ms
# new_sum string with block
#                          6.790k i/100ms
# -------------------------------------------------
# old_sum string with block
#                          69.845k (±19.3%) i/s -    343.408k
# new_sum string with block
#                          74.767k (±21.1%) i/s -    359.870k
#
# Comparison:
# new_sum string with block:    74767.3 i/s
# old_sum string with block:    69844.7 i/s - 1.07x slower