Imperative way of splitting paired-end FASTA in Scala

import java.io.PrintWriter
import java.io.File

val fileName = args(0)
val p1 = new PrintWriter(new File(fileName + ".1"))
val p2 = new PrintWriter(new File(fileName + ".2"))
var count = 0

for (l <- io.Source.fromFile(fileName).getLines) {
    if (l startsWith ">") count = count + 1
    count % 2 match {
        case 1 => p1 print (l + "\n")
        case 0 => p2 print (l + "\n")
    }
}; p1.close; p2.close
println("Done bro!")
println("Seems to work fine, but concise imperative code is still imperative code :(")