with_index_vs_each_with_index.rb

# This code is based on the code at blow:
# https://github.com/fastruby/fast-ruby/tree/main/code/enumerable
require "benchmark/ips"

ARRAY = [*1..100]

def fast
  ARRAY.each.with_index(1) do |number, index|
    index
  end
end

def slow
  ARRAY.each_with_index do |number, index|
    index + 1
  end
end

Benchmark.ips do |x|
  x.report("each.with_index") { fast }
  x.report("each_with_index") { slow }
  x.compare!
end

# ruby 3.2.2 (2023-03-30 revision e51014f9c0) [x86_64-darwin22]
# Warming up --------------------------------------
#      each.with_index    11.362k i/100ms
#      each_with_index    10.486k i/100ms
# Calculating -------------------------------------
#      each.with_index    114.349k (± 0.7%) i/s -    579.462k in   5.067760s
#      each_with_index    105.667k (± 0.5%) i/s -    534.786k in   5.061186s
# 
# Comparison:
#      each.with_index:   114348.7 i/s
#      each_with_index:   105666.7 i/s - 1.08x  slower
#