Learning languages in comparison. How Scala re-introduces what was dropped in C++ to create Java.

An update (30/11/2008): I realize that a title of this post sounds silly. I never tried to say something like "Scala has C++ roots" or so. Scala is "an attempt to come up with a decent statically typed language that is both functional and object-oriented and that interoperates on standard VMs" (Martin Odersky in a comment here). My point is: too much (including some functional features) was dropped when C++ was "simplified" by Java creators. 

Scala allows to pass variable length argument list to a function defined like

def echo(args: String*) =

  for (arg <- args) println(arg)

In "Programming in Scala" authors says that,

'... Thus, the type of args inside the echo function, which is declared as type "String*"  is actually Array[String]'

It immediatelly reminds me C++, which uses similar syntax of passing array arguments. I'm pretty sure Martin Odersky chose asterisk, because it is used in C/C++, although in C/C++ it allows to pass array parameters, not a variable length argument list, and denotes a pointer to a first element of array.

There is definitely a feel, that C++ is more functional language than Java, for example a name of a function is a pointer (reference) variable pointing to a function itself, which allows to pass a function to another function as parameter and return as return value. First-class functions, isn't it?

So, Scala feels partly as a consistent attempt to re-introduce to Java functional features which were dropped when Java creators used C++ to produce new [over?]simplified language.

Personally, I always loved when authors of books described new languages in comparison to existing ones, like Trey Nash is doing in his "Accelerated C# 2008", comparing C# to C++, like David Flanagan is doing in "JavaScript. The Definite Guide", comparing JavaScript to C/C++, and like Bruce Eckel is doing in "Thinking in Java", comparing it to... C++ again. (By the way, Bruce is considering Scala as a next "big" language, which will gradually and partially replace Java the same way Java did to C++.) One fresh and excellent example is "Real World Functional programming in .NET" by Tomas Petricek. This book introduces F# language (a merge of OCaml and .NET platform) and functional concepts in constant comparison to limited functional features of C# 3.0. It helps a lot to understand both F# and functional features of C#. It even helps to understand Scala, because functional concepts are the same in both F# and Scala.

To learn programming languages in comparison is not an easy task. But it is, in my opinion, a most powerful way to obtain real understanding of languages. Footnotes or special text blocks, describing similarities and diffrence between languages make a programming book shine.