Compare Monads with Pure Ruby

monads.rb

require 'benchmark/ips'
require 'dry/monads/result'

extend Dry::Monads::Result::Mixin

def pure_square(x)
	value = x ** 2
	
	if value > 50
		return :number_too_large
	else
		return value
	end
end

def mixed_square(x)
	value = x ** 2
	
	if value > 50
		return Failure(:number_too_large)
	else
		return Success(value)
	end
end

# Taken from https://www.morozov.is/2018/09/08/monad-laws-in-ruby.html
def monad_square(x)
	Success(x).bind do |value|
		Success(value ** 2)
	end.bind do |value|
		if value > 50
			Failure(:number_too_large)
		else
			Success(value)
		end
	end
end


require 'benchmark/ips'

Benchmark.ips do |x|
	x.report("pure_square(10)") do |times|
		while (times -= 1) >= 0
			pure_square(10)
		end
	end
	
	x.report("mixed_square(10)") do |times|
		while (times -= 1) >= 0
			mixed_square(10)
		end
	end
	
	x.report("monad_square(10)") do |times|
		while (times -= 1) >= 0
			monad_square(10)
		end
	end
	
	x.compare!
end

# Warming up --------------------------------------
#      pure_square(10)   439.179k i/100ms
#     mixed_square(10)    57.390k i/100ms
#     monad_square(10)    30.903k i/100ms
# Calculating -------------------------------------
#      pure_square(10)     18.275M (± 8.0%) i/s -     90.471M in   4.999792s
#     mixed_square(10)    654.150k (± 9.1%) i/s -      3.271M in   5.050263s
#     monad_square(10)    336.968k (± 5.1%) i/s -      1.700M in   5.058423s
# 
# Comparison:
#      pure_square(10): 18275153.1 i/s
#     mixed_square(10):   654150.0 i/s - 27.94x  slower
#     monad_square(10):   336968.4 i/s - 54.23x  slower