Main.scala

%s should %s be balanced".format(s,
                                               if (!expected) "NOT" else ""))
    testBalance("(if (zero? x) max (/ 1 x))")
    testBalance("I told him (that it's not (yet) done)." +
                      "(But he wasn’t listening)")
    testBalance(":-)", expected = false)
    testBalance("())(", expected = false)

  }

  /**
   * Exercise 1
   */
  def pascal(c: Int, r: Int): Int = {
    require(c >= 0 && r >= 0,
            "only positive coord please (%d, %d)".format(c, r))
    require(c <= r,
           ("the number of columns of row %d is exactly %d," +
           "column %d is out sorry (starting from 0)").format(r,r+1,c))
    (c, (r - 1)) match {
      case (_, x) if x < 1 => 1
      case (0, _) => 1
      case (x, y) if x > y => 1
      case (x, y) => pascal(x - 1, y) + pascal(x, y)
    }
  }

  /**
   * Exercise 2