Scala vs Ruby

1. no ; at the end of lines

2. base operate

scala:

val list = Array(1,2,3,4)  

list.filter( _ % 2 == 0)
list.filter{e: Int => (e % 2 == 0)}

ruby:

list = [1,2,3,4]
list.select{|x| x % 2 == 0}

3. staic types

scala:

import scala.collection.mutable.HashMap
var hash =new HashMap[Int, String]
hash += (1 -> "hello")
hash += (3) #error: type mismatch; 

ruby:

hash = Hash.new
hash = 3 #3

4. Dynamic calls

scala:

import scala.language.dynamics

class Animal extends Dynamic {
  def selectDynamic(name: String) {
    println("Animal wants to " + name)
  }

  def applyDynamic(name: String)(args: Any*) {
    println("Animal wants to " + name + args.mkString(","))
  }
}

scala> var a = new Animal
scala> a.say
Animal wants to say
scala> a.say("hello")
Animal wants to say hello

ruby:

class Animal
  def method_missing name,*args
    if args.empty?
      puts "Animal says " + name.to_s
    else
      puts "Animal wants to " + name.to_s + args.join(",")
    end
    self
  end
end

2.2.1 :020 > animal = Animal.new
2.2.1 :020 > animal.qualk
Animal says qualk
2.2.1 :021 > animal.say("hello")
Animal wants to say hello

5. minxin

scala:

trait MyClass {
  def my_method = println("my method")
}
class IncludeTrait extends MyClass
scala> (new IncludeTrait).my_method
my method

ruby:

module MyModule
  def my_method
    puts "my_method"
  end
end

class IncludeModule
  include MyModule
end

2.2.1 :032 >IncludeModule.new.my_method
my_method

6. duck type

scala:

class Duck{
  def quack = { println("duck quack..")}
  def walk = { println("duck walk..")}
}


class Platypus{
  def quack = { println("platypus quack..")}
  def walk = { println("platypus walk..")}
}

def ActAsADuck(a: {def quack; def walk}) = {
  a.quack
  a.walk
}

val duck  = new Duck
val paltypus = new Platypus
ActAsADuck(duck)
ActAsADuck(platypus)

ruby:

class Duck
  def quack; end
  def walk; end
end

class Platypus
  def quack; end
  def walk; end
end

def act_as_a_duck(animal)
  animal.quack
  animal.walk
end

duck = Duck.new
platypus = Platypus.new

act_as_a_duck(duck)
act_as_a_duck(platypus)

7. unit test

scala:

@Test def myTest(){
  val array = List(1,2,3)
  assert(array(0) === 1)
}

ruby:

test "my test" do 
  array = [1,2,3]
  assert_equal 1, array.first
end

8. spec test

scala:

describe("Get of List"){
  it("(0) returns the first element")  {
    val array = List(1,2,3)
    array(0) should be 1
  }
}

ruby :

describe "Get of Array" do 
 it "first returns the first element" do 
   array = [1,2,3]
   array.first.should == 1
  end
end

9. web platform

scala:

Play 是一个开源高性能 Web 框架，能够基于 Java 或 Scala 编写可扩展可伸缩的应用系统，它能自动刷新源码的变动从而具有快速开发产品的能力，它还是一个无态非堵塞的框架，易于横向扩展。Play! 框架有如下特点：高开发效率：Java EE 和 Spring 框架并不适合快速原型开发，Play 框架参考动态语言的快速开发能力，它支持热重载所有的 Java 代码和模板等，让你更快地迭代。基于 Netty 构建非堵塞异步机制。RESTJSON 支持：非常容易编写 RESTful 应用，非常适合支持 HTTP 路由。

Akka 是一个用 Scala 编写的库，用于简化编写容错的、高可伸缩性的 Java 和 Scala 的 Actor 模型应用。它已经成功运用在电信行业。系统几乎不会宕机（高可用性 99.9999999% 一年只有 31ms 宕机

ruby: Ruby on Rails 是一个用于开发数据库驱动的网络应用程序的完整框架。Rails 基于 MVC 设计模式。从视图中的 Ajax 应用，到控制器中的访问请求和反馈，到封装数据库的模型，Rails 为你提供一个纯 Ruby 的开发环境。发布网站时，你只需要一个数据库和一个网络服务器即可。

10. performance

http://www.slideshare.net/El_Picador/scala-vs-ruby