Tak, to będzie moje dzieło. Nie rozumiem Pańskiego negatywnego podejścia. Nikt tu nie zamierza „zwalać” z zagranicznych książek. Co więcej, mam nadzieje, że uda mi się zaprezentować świeże podejście do niektórych tematów. To czy książka będzie gniotem, czy nie, to ocenią już czytelnicy.

http://helion.pl/ksiazki/programowanie-w-jezyku-scala-od-podstaw-wojciech-soczynski,prscal.htm

Ach te polaczki zwalają z zagranicznych książek i potem wydają pod swoim nazwiskiem???

Na amazon.com jest książka o Scali napisana przez samych twórców języka więc nie kupie tego gniota z helionu.

Programming in Scala: A Comprehensive Step-by-Step Guide, 2nd Edition
Martin Odersky

Świetny blog!

I dont fight over anything. I just think that these are two different concepts which have a similar effect. It is as a train and a car, both serve to get from point A to point B but work in a different way.

I think were fighting over terminology here.

What do you think polymorphism means?
What do you think duck typing means?

I personally think that duck typing is a polymorphism mechanism, so duck typing -> polymorphism.

Polymorphism has nothing to do with type checking for me.

I wrote a stackoverflow question about what’s „correct” : http://programmers.stackexchange.com/questions/121778/is-duck-typing-a-subset-of-polymorphism

Duck typing is a bit different concept than polymorphism. With duck typing you don’t care about the object type, until it behaves according to some contract (for example defined as a set of unit tests). So in case of Javascript, we could tell, that the language supports duck typing, because you can write an application, that does not check for specific types, and just assumes that some object has some method.

With polymorphism, the only way you can enforce types is via the instanceOf operator or isPrototypeOf function, with the latter checking the whole prototype chain. So I would tell, that Javascript supports some form of prototypal polymorphism, although very different from the class based polymorphism that we know from a classic (java/c++) like oop model.

> polymorphism

Polymorphism simply means that any function which expects type X can take any object which inherits from type X.

So if you have a Person [[Prototype]] and you let FitnessAddict by a [[Prototype]] that inherits from it.

Then any function which expects an argument with [[Prototype]] === Person will work with an argument whoms [[Prototype]] == FitnessAddict.

This ties in with duck typing. We are doing polymorphism by defining an interface (in your head / documentation) that a function accepts. And the fact that as long as an object implements that interface it will work is what it means to do polymorphism