Roots of a function

func f(x) {
    x*x*x - 3*x*x + 2*x
}

var step = 0.001
var start = -1
var stop = 3

for x in range(start+step, stop, step) {
    static sign = false
    given (var value = f(x)) {
        when (0) {
            say "Root found at #{x}"
        }
        case (sign && ((value > 0) != sign)) {
            say "Root found near #{x}"
        }
    }
    sign = value>0
}

Output:

Root found at 0
Root found at 1
Root found at 2