Beginner: Scala type alias in Scala 2.10?

Question

Why does this code fail to compile with the error: not found: value Matrix? From the documentation and some (possibly out of date) code examples this should work?

Answer 1

Matrix denotes a type, but you are using it as a value.

When you do List(1, 2, 3), you are actually calling List.apply, which is a factory method for List.

To fix your compiling error, you can define your own factories for Matrix and Row:

object TestMatrix extends App{  
  type Row = List[Int]
  def Row(xs: Int*) = List(xs: _*)

  type Matrix = List[Row]
  def Matrix(xs: Row*) = List(xs: _*)

  val m = Matrix( Row(1,2,3),
      Row(1,2,3),
      Row(1,2,3)
      )
}