Scala IDE Beta 2 Seems to Work!
In the last year or so I've been working to Scala. Initally when I came across Scala, there was an Eclipse plug-in that was supposed to be the development environment for Scala. Back then, I tried it and it worked, but only for very trivial cases. It was in its infancy. Surprisingly, as the language matured, the IDE seemed move in the wrong direction, progressively getting worse and worse. In fact, the last time I remember taking it for a spin, I couldn't even create an empty Scala project. Nothing worked. I since then have been working with emacs ENSIME and sbt. I've been satisfied with that environment, but I'm always wanting more.
A few (maybe a dozen or so) months have passed since I've looked at the Eclipse environment for Scala, so I figured I'd give it a try today.
I downloaded a fresh copy of Helios, installed the plugin and off I went. Very surprisingly, it worked. Well, the following file did.
It's a trivial example to be sure, but this much code never worked for me in any of the previous releases. This is fantastic news, because one of the things that will help with Scala adoption, and particularily in adoption from Java developers who are already on the JVM, is a development environment that the community is comfortable with.
Kudos to the Scala IDE team.
Here's the code from the demo if you want to try it yourself.
package euler
import scala.actors.Actor
import Actor._
object Euler011 extends Actor {
type Matrix = Seq[Seq[Int]]
case class CalculateMaxRequest(matrix: Matrix, from: Actor)
case class CalculateMaxReply(matrix: Matrix, max: Int)
var count = 0
def execute() {
val input = "08 02 22 97 38 15 00 40 00 75 04 05 07 78 52 12 50 77 91 " +
"08 49 49 99 40 17 81 18 57 60 87 17 40 98 43 69 48 04 56 " +
"62 00 81 49 31 73 55 79 14 29 93 71 40 67 53 88 30 03 49 " +
"13 36 65 52 70 95 23 04 60 11 42 69 24 68 56 01 32 56 71 " +
"37 02 36 91 22 31 16 71 51 67 63 89 41 92 36 54 22 40 40 " +
"28 66 33 13 80 24 47 32 60 99 03 45 02 44 75 33 53 78 36 " +
"84 20 35 17 12 50 32 98 81 28 64 23 67 10 26 38 40 67 59 " +
"54 70 66 18 38 64 70 67 26 20 68 02 62 12 20 95 63 94 39 " +
"63 08 40 91 66 49 94 21 24 55 58 05 66 73 99 26 97 17 78 " +
"78 96 83 14 88 34 89 63 72 21 36 23 09 75 00 76 44 20 45 " +
"35 14 00 61 33 97 34 31 33 95 78 17 53 28 22 75 31 67 15 " +
"94 03 80 04 62 16 14 09 53 56 92 16 39 05 42 96 35 31 47 " +
"55 58 88 24 00 17 54 24 36 29 85 57 86 56 00 48 35 71 89 " +
"07 05 44 44 37 44 60 21 58 51 54 17 58 19 80 81 68 05 94 " +
"47 69 28 73 92 13 86 52 17 77 04 89 55 40 04 52 08 83 97 " +
"35 99 16 07 97 57 32 16 26 26 79 33 27 98 66 88 36 68 87 " +
"57 62 20 72 03 46 33 67 46 55 12 32 63 93 53 69 04 42 16 " +
"73 38 25 39 11 24 94 72 18 08 46 29 32 40 62 76 36 20 69 " +
"36 41 72 30 23 88 34 62 99 69 82 67 59 85 74 04 36 16 20 " +
"73 35 29 78 31 90 01 74 31 49 71 48 86 81 16 23 57 05 54 " +
"01 70 54 71 83 51 54 69 16 92 33 48 61 43 52 01 89 19 67 " +
"48"
val intArray = input split " " map (_.toInt) toList
val array2D = (intArray grouped 20 toList)
val sliced = array2D.map(row => row.sliding(4, 1).toList).sliding(4, 1).toList
val matrices: List[Matrix] = sliced flatMap (_.transpose)
count = matrices.size
println("We have " + count + " matrices to process, each using an actor")
for (matrix <- matrices) {
val calculator = new MaxProductCalculator
calculator.start()
calculator ! CalculateMaxRequest(matrix, this)
}
}
var max = 0
override def act() = loop {
react {
case CalculateMaxReply(matrix, maxProduct) =>
max = if (maxProduct > max) maxProduct else max
count -= 1
if (count == 0) {
println("Found it. The answer is " + max)
exit()
}
}
}
class MaxProductCalculator extends Actor {
override def act() = loop {
react {
case CalculateMaxRequest(matrix, actor) =>
actor ! CalculateMaxReply(matrix, calculateMax(matrix))
exit()
}
}
def calculateMax(matrix: Matrix) = {
def calculateDiagonals(matrix: Matrix) = {
var leftTotal = 1
var rightTotal = 1
val end = matrix.size - 1
for (i <- 0 to end) {
leftTotal = leftTotal * matrix(i)(i)
rightTotal = rightTotal * matrix(end - i)(i)
}
(leftTotal, rightTotal)
}
val horizontal = matrix.map(_ product).max
val vertical = matrix.transpose.map(_ product).max
val (left, right) = calculateDiagonals(matrix)
val products = horizontal :: vertical :: left :: right :: Nil
products max
}
}
}
object Runner extends Application {
Euler011.start
Euler011.execute
}