Scala syntax problem

The following code can be compiled

开发者_如何学运维  def isEven(a:Int)=
    if (a%2==0) true else false

  def main(args: Array[String]) {
        List(1, 10) filter isEven foreach println

but if I change to following ( List(1,10) --> List(1 to 10))

def isEven(a:Int)=
    if (a%2==0) true else false

  def main(args: Array[String]) {
        List(1 to 10) filter isEven foreach println
   }

What's difference between List(1,10) and List(1 to 10) ?

List(1, 2) is simply a list with two Int elements: 1 and 2. The expression 1 to 10 creates a Range instance, so List(1 to 10) is a list with one element: a Range.

List(1, 10) is a List[Int] whereas List(1 to 10) is a List[Range]. Observe the types in the following REPL session:

scala> 1 to 10
res3: scala.collection.immutable.Range.Inclusive with scala.collection.immutable.Range.ByOne = Range(1, 2, 3, 4, 5, 6, 7
, 8, 9, 10)

scala> List(1 to 10)
res4: List[scala.collection.immutable.Range.Inclusive with scala.collection.immutable.Range.ByOne] = List(Range(1, 2, 3,
 4, 5, 6, 7, 8, 9, 10))

scala> List(1, 10)
res5: List[Int] = List(1, 10)

missingfaktor is right, so this is just an addition.

If you want a List[Int] with numbers from 1 to 10, you can write

List(1 to 10:_*)

or

1 to 10 toList