gistfile1.txt

#!/usr/bin/env ruby
# frozen_string_literal: true

require 'benchmark/ips'

def num
  @num ||= 2**18
end

def foo
  @foo ||= Array.new(num) { nil }.compact.any?
end

def bar
  return @bar if defined? @bar

  (@bar = Array.new(num) { nil }.compact.any?)
end

Benchmark.ips do |benchmark|
  benchmark.config(time: 5, warmup: 5)
  benchmark.report('foo') { foo }
  benchmark.report('bar') { bar }
  benchmark.compare!
end

# Warming up --------------------------------------
#                  foo     5.000  i/100ms
#                  bar   246.574k i/100ms
# Calculating -------------------------------------
#                  foo     59.063  (± 3.4%) i/s -    295.000  in   5.000007s
#                  bar      7.013M (± 2.9%) i/s -     35.260M in   5.032246s

# Comparison:
#                  bar:  7013241.0 i/s
#                  foo:       59.1 i/s - 118741.56x  slower