benchmark_results

[1, 0, 2, 1, 0, 2, 1, 0, 2, 1]
[1, 0, 2, 1, 0, 2, 1, 0, 2, 1]
[1, 0, 2, 1, 0, 2, 1, 0, 2, 1]

       user     system      total        real
eager_map  0.370000   0.010000   0.380000 (  0.373325)
lazy_map  1.130000   0.010000   1.140000 (  1.142926)
composed  0.540000   0.000000   0.540000 (  0.545507)

                             user     system      total        real
eager_map x 1            0.000000   0.000000   0.000000 (  0.000013)
eager_map x 10           0.000000   0.000000   0.000000 (  0.000015)
eager_map x 100          0.000000   0.000000   0.000000 (  0.000050)
eager_map x 1000         0.000000   0.000000   0.000000 (  0.000334)
eager_map x 10000        0.000000   0.000000   0.000000 (  0.003235)
eager_map x 100000       0.040000   0.000000   0.040000 (  0.038602)
eager_map x 1000000      0.330000   0.010000   0.340000 (  0.333256)
eager_map x 10000000     3.650000   0.080000   3.730000 (  3.748070)

                             user     system      total        real
lazy_map x 1             0.000000   0.000000   0.000000 (  0.000038)
lazy_map x 10            0.000000   0.000000   0.000000 (  0.000035)
lazy_map x 100           0.000000   0.000000   0.000000 (  0.000114)
lazy_map x 1000          0.000000   0.000000   0.000000 (  0.000887)
lazy_map x 10000         0.030000   0.000000   0.030000 (  0.033165)
lazy_map x 100000        0.100000   0.020000   0.120000 (  0.116230)
lazy_map x 1000000       0.980000   0.000000   0.980000 (  0.980008)
lazy_map x 10000000     10.010000   0.020000  10.030000 ( 10.066494)

                             user     system      total        real
composed x 1             0.000000   0.000000   0.000000 (  0.000023)
composed x 10            0.000000   0.000000   0.000000 (  0.000012)
composed x 100           0.000000   0.000000   0.000000 (  0.000066)
composed x 1000          0.000000   0.000000   0.000000 (  0.000498)
composed x 10000         0.010000   0.000000   0.010000 (  0.004791)
composed x 100000        0.050000   0.000000   0.050000 (  0.048782)
composed x 1000000       0.510000   0.000000   0.510000 (  0.515904)
composed x 10000000      5.410000   0.050000   5.460000 (  5.484562)

func_comp_gen.rb

#!/usr/bin/env ruby

require 'benchmark'

DOUBLE = -> (i) { 2 * i }
ADD_TWO = -> (i) { 2 + i }
MOD_THREE = -> (i) { i % 3 }

COMPOSED = -> (i) do
  MOD_THREE.call(ADD_TWO.call(DOUBLE.call(i)))
end

def get_enumerator count
  i = 0
  Enumerator.new do |y|
    y.yield i while count >= i += 1
  end
end

def demo
  p eager_map(get_enumerator 10).to_a
  p composed(get_enumerator 10).to_a
  p lazy_map(get_enumerator 10).to_a
  puts
end

def eager_map items
  items.map(&DOUBLE).map(&ADD_TWO).map(&MOD_THREE)
end

def lazy_map items
  items.lazy.map(&DOUBLE).map(&ADD_TWO).map(&MOD_THREE)
end

def composed items
  items.map &COMPOSED
end

demo

n = 1_000_000
Benchmark.bm do |x|
  x.report('eager_map') { eager_map(get_enumerator n).count }
  x.report('lazy_map') { lazy_map(get_enumerator n).count }
  x.report('composed') { composed(get_enumerator n).count }
end


[:eager_map, :lazy_map, :composed].each do |method|
  puts

  Benchmark.bm(22) do |x|
    (0..7).each do |e|
      x.report("#{method} x #{10 ** e}") { self.send(method, get_enumerator(10 ** e)).count }
    end
  end
end