Publish to my blog (weekly)

• 코딩 코리아(Coding Korea): 스칼라의 TypeTag

  • 위에 예제에서 볼수 있듯이 스칼라의 Manifest 는 Path dependent type 을 정확하게 확인할수 없는  결함을 갖고있다(스칼라에서 Path dependent type 은 같은 타입의 클라스라도 exact path 에 따라 instance 들이 틀리다고 명제되어있다. 그러므로 위의 경우에서도 둘다 Foo.Bar 이지만 path 가 틀리기 때문에 두 클라스의 Manifest 는 동일하지 않아야한다.)
  • Manifest 처럼 TypeTag 의외도 ClassTypeTag 과 WeakTypeTag 이 있다. ClassTag 은 ClassManfiest 처럼 가장 위의 레벨에 있는 class type 만 생성한다.
  • // ClassTag 은 Runtime 에서 오직 맨위에 레벨의 class type 만 제공하는것을 볼수있다
  • // 그러므로 Full type information 이 필요하면 TypeTag 을 써야한다
  • WeakTypeTag 은 주로 Macro 를 사용할때 같이 사용하게 된다.
  • scala> def foo[T: TypeTag] = implicitly[TypeTag[T]]
  • foo[Int]
  • def bar[T] = foo[T]
  • scala> def foo[T: WeakTypeTag] = implicitly[WeakTypeTag[T]]
  • foo[Int]
  • def bar[T] = foo[T]

• Relevant Search.pdf

• Scala: Multiple type parameters for implicit class - Stack Overflow

  •   down vote     accepted  

             

     

    Implicit classes don't work that way. They are a shorthand for implicit conversions. For instance implicit class Foo(i: Int) is equal to class Foo(i: Int); implicit def Foo(i: Int) = new Foo(i)

• A Scala 2.10 implicit class example (how to add new functionality to closed classes) | alvinalexander.com

  • A class
  •  
    • An object
     
    • A package object
  • SIP-13, Implicit Classes, “An implicit class must be defined in a scope where method definitions are allowed (not at the top level).”
  • Putting Common Code in Package Objects,
  • you can add new functionality to closed classes by writing implicit conversions and bringing them into scope when you need them.
  • there’s no need to create a new class named MyString that extends String, and then use MyString throughout your code instead of String; instead, you define the behavior you want, and then add that behavior to all String objects in the current scope when you add the import statement.
  • how this works:
  • The compiler sees a string literal HAL.
  • The compiler sees that you’re attempting to invoke a method named increment on the String.
  • Because the compiler can’t find that method on the String class, it begins looking around for implicit conversion methods that are in scope that accept a String argument.
  • This leads the compiler to the StringImprovements class, where it finds the increment method.
  • : String
  • : String
  • : String

• Rust: A Scala Engineer's Perspective - BeachApe.

  • Rust’s memory/ownership model is, to me, its main killer feature;

Posted from Diigo. The rest of my favorite links are here.