Pattern matching not matching given variable

Question

I have made an implementation of the pascal's triangle but something is wrong with it since when col match { case row => ...} it doesn't correctly match the col with the row:

def main(args: Array[String]) {
println("Pascal's Triangle")
for (row <- 0 to 10) {
  for (col <- 0 to row) {
    val res: Int = pascal(col, row)
    print(res + " ")
  }
  println()
}

def pascal(col: Int, row: Int): Int = {
    col match {
      case 0 => 1
      case row => 1
      case _ => pascal(col-1, row-1) + pascal(col, row-1)
    }
}

Answer 1

Your row match is shadowing the method parameter. To achieve what you want, you could try to use so called guards for your pattern match, e.g.

case n if n == row => 1

With this, you have 3 cases, the 0 case, the case when n is equal to given row parameter and the default case. Otherwise, the row match would match all remaining numbers not equal to 0, which will leave the _ match at the end never be triggered.