State (write) dry-effect

console.sh

✓ ruby stack.rb 
What do you want to do? (add, remove, see, count)
see
#<Plate:0x0000557c3f0598b0>
What do you want to do? (add, remove, see, count)
add
#<Plate:0x0000557c3f059c20>
#<Plate:0x0000557c3f0598b0>
#<Plate:0x0000557c3f890ce0>
What do you want to do? (add, remove, see, count)
count   
3
What do you want to do? (add, remove, see, count)
see
#<Plate:0x0000557c3f890ce0>
What do you want to do? (add, remove, see, count)
remove
#<Plate:0x0000557c3f059c20>
#<Plate:0x0000557c3f0598b0>
What do you want to do? (add, remove, see, count)
count
2
What do you want to do? (add, remove, see, count)
remove
#<Plate:0x0000557c3f059c20>
Bye!

stack.rb

require 'bundler/inline'

gemfile do
  source 'https://rubygems.org'
  gem 'dry-effects'
end
require 'dry/effects'

class Plate; end
class Stack
  def initialize(size)
    @stack = size.times.map{ |_| Plate.new }
  end

  private attr_reader :stack

  def push(value)
    stack.push(value)
  end

  def pop
    stack.tap(&:pop)
  end

  def peek
    stack.last
  end

  def stock
    stack.size
  end
end

class App
  include Dry::Effects::Handler.State(:stack)


  def initialize
    @stack = Stack.new(2)
  end

  def call
    with_stack(@stack) do
      Machine.new.call
    end
    puts "Bye!"
  end
end

class Machine
  include Dry::Effects.State(:stack)

  def call
    while stack.stock > 1
      puts "What do you want to do? (add, remove, see, count)"
      input = gets.chomp
      case input
        when "add" then puts stack.push(Plate.new)
        when "remove" then puts stack.pop
        when "see" then puts stack.peek
        when "count" then puts stack.stock
        else puts "Wrong input, allowed commands: add, remove, see, count"
      end
    end
  end
end

app = App.new.()