pascal triangle and recursive pascal function done in groovy

pascal.groovy

    def pascal(col, row) {
        assert col >= 0 && row >= 0 && col <= row
        if (col == 0 || row == 1 || col == row)
            return 1
        return pascal(col - 1, row - 1) + pascal(col, row - 1)
    }

    def triangle(rows) {
        assert rows >= 0
        (0..rows).each { row ->
            (0..row).each { col ->
                print(pascal(col, row) + ' ')
            }
            println()
        }
    }