gistfile1.java

object MartelliEstimator {
	def main(args : Array[String]) : Unit = {
		for (bought <- 0 until 5) {
			val result = estimate(List(0.3, 0.7), bought, 4-bought)
			println("b="+bought+", p="+result)
		}
	}
	
	def estimate(priorProbs : List[Double], successes : Int, failures : Int) : Double = {
		val condProbs = priorProbs.map( p => Math.pow(p, successes) * Math.pow(1.0-p, failures))
		val normalize = 1.0 / sum(condProbs)
		val priorMeta = condProbs.map(cp => normalize * cp)
		sum(priorMeta.zip(priorProbs).map({case (a, b) => a*b}))
	}
	
	private def sum (l : List[Double]) : Double = {
			l.foldRight (0.0) (_ + _)
	}
}