Wednesday, June 8, 2011

Amazed by Scala

Top stock of 2008 is GOOG closing at price 307,650000 among (AAPL, GOOG, IBM, MSFT). Amazed by simplicity, clarity and beauty of the following code in Scala from this book.



import scala.actors._
import Actor._

val symbols = List( "AAPL", "GOOG", "IBM", "MSFT")
val receiver = self
val year = 2008

symbols.foreach { symbol =>
actor { receiver ! getYearEndClosing(symbol, year) }
}

val (topStock, highestPrice) = getTopStock(symbols.length)

printf("Top stock of %d is %s closing at price %f\n", year,
topStock, highestPrice)

def getYearEndClosing(symbol : String, year : Int) = {
val url = "http://ichart.finance.yahoo.com/table.csv?s="+
symbol + "&a=11&b=01&c=" + year + "&d=11&e=31&f=" + year+
"&g=m"

val data = io.Source.fromURL(url).mkString
val price = data.split("\n")(1).split(",")(4).toDouble
(symbol, price)
}

def getTopStock(count : Int) : (String, Double) = {
(1 to count).foldLeft("", 0.0) { (previousHigh, index) =>
receiveWithin(10000) {
case (symbol : String, price : Double) =>
if (price > previousHigh._2) (symbol, price) else
previousHigh
}
}
}

No comments: