Why does not ; equivalent to the eol?

Question

Here is the code that compiles as intended

  def coarse_grained: Int = {
    def fib: Int = List(1,2) sum ;
    fib
  }

and one which does not

  def coarse_grained: Int = {
    def fib: Int = List(1,2) sum
    fib
  }

The only difference is ; after the sum.

Answer 1

As you know, List(2,6,9).drop(1) can also be written as List(2,6,9) drop 1. In fact, it can also be written like this.

List(2,6,9) drop
1

The compiler keeps looking for the final argument, even past a newline. So if you want to do this List(1,2).sum like this List(1,2) sum, you'll need to use the semicolon ; to tell the compiler to stop looking for the final argument. It's not coming.