Lazy chining

lazy_chaining.rb

require 'benchmark'
require 'benchmark/ips'

NORMAL_ITERATIONS = 100
LONG_ITERATIONS = 2000

def map_to_self(array, iterations)
  iterations.times do
    array = array.map{ |i| i }
  end

  array
end

Benchmark.ips do |x|
  x.report('[n] iterative') {
    map_to_self([1], NORMAL_ITERATIONS).to_a
  }

  x.report('[n] lazy preparation') {
    map_to_self([1].lazy, NORMAL_ITERATIONS)
  }

  x.report('[n] lazy evaluation') {
    map_to_self([1].lazy, NORMAL_ITERATIONS).to_a
  }

  x.report('[l] iterative') {
    map_to_self([1], LONG_ITERATIONS).to_a
  }
end

lazy_long_map = map_to_self([1].lazy, LONG_ITERATIONS)
begin
  lazy_long_map.to_a
rescue SystemStackError
  puts 'Lazy chaining is recursive o_O'
end

output.txt

Calculating -------------------------------------
       [n] iterative     6.764k i/100ms
[n] lazy preparation   380.000  i/100ms
 [n] lazy evaluation   224.000  i/100ms
       [l] iterative   340.000  i/100ms
-------------------------------------------------
       [n] iterative     69.078k (± 2.3%) i/s -    351.728k
[n] lazy preparation      3.760k (± 4.6%) i/s -     19.000k
 [n] lazy evaluation      2.267k (± 2.0%) i/s -     11.424k
       [l] iterative      3.717k (± 1.5%) i/s -     18.700k
Lazy chaining is recursive o_O