pass-by-name

Given this Scala code: object test { def byval(a: Int) = println("Int") def byval(a: Long) = println("Long") def byname(a: => Int) = println("=> Int") def byname(a: => Long) = println("=> Long") def main(args: Array[String]) { byval(5) byname(5) } } the call byval(5) compiles correctly, but byname fails to compile: ambiguous reference to overloaded definition Why? I would expect to observe the same behavior for by-value and by-name parameters with respect to overloading… How can it be fixed? That's because JVM does not support a "by-name" parameter, so Scala has to implement it in another way.

In python we can do this: def myFun1(one = '1', two = '2'): ... Then we can call the function and pass the arguments by their name: myFun1(two = 'two', one = 'one') Also, we can do this: def myFun2(**kwargs): print kwargs.get('one', 'nothing here') myFun2(one='one') So I was wondering if it is possible to combine both methods like: def myFun3(name, lname, **other_info): ... myFun3(lname='Someone', name='myName', city='cityName', otherInfo='blah') In general what combinations can we do? Thanks and sorry for my silly question. The general idea is: def func(arg1, arg2, ..., kwarg1=default, kwarg2

I am going through the book "Functional Programming in Scala" and have run across an example that I don't fully understand. In the chapter on strictness/laziness the authors describe the construction of Streams and have code like this: sealed trait Stream[+A] case object Empty extends Stream[Nothing] case class Cons[+A](h: () => A, t: () => Stream[A]) extends Stream[A] object Stream { def cons[A](hd: => A, tl: => Stream[A]) : Stream[A] = { lazy val head = hd lazy val tail = tl Cons(() => head, () => tail) } ... } The question I have is in the smart constructor ( cons ) where it calls the