如何在Scala中返回Map

Question

I just started playing with scala and i cross the following issue. I want to simply return a Map with Int as key and List of Tuples for values. That is my method:

  def findOpenTiles(board: Array[Array[Int]]): Map[Int, List[(Int, Int)]]={

    val openTilesMap = Map[Int, List[(Int, Int)]]
    for (x <- 0 until Constant.boardWidth; y <- 0 until Constant.boardHeight) yield {
      if (hasOpenTile(board, x, y)){
        // add to values to openTilesMap 
      }
    }
    openTilesMap
  }

However my IDE shows error as:

Expression of type (Seq[(Int, List[Int, Int])]) => Map[Int, List[(Int, Int)]] doesn't conform to expected type Map[Int, List[(Int, Int)]]

Does it mean that val openTilesMap = Map[Int, List[(Int, Int)]] creates Seq of Tuples (Int, List[Int, Int]) instead of Map? If so, how can i make it return Map?

// edit

I'm trying to write a bot to javascript game. I'm mapping a board of tiles. In the mentioned method I am trying to find all "open tiles" (tiles which are not fully surounded by other tiles, thus can be moved) and in the return i would like to have a Map where key is a tile number with coordinates as values. In next step i want to find if it is possible to find path between "open" tiles with the same number.

Answer 1

I think the problem is the line

val openTilesMap = Map[Int, List[(Int, Int)]]

You should try this:

val openTilesMap: Map[Int, List[(Int, Int)]] = Map()

Your version assigns the type Map[Int, List[(Int, Int)]] to the value openTilesMap .