Scala 2 vs. 3 optional control syntax changes.

scala2-3-controls.scala

for (i <- 0 until 5) println(i)   // Original syntax
for i <- 0 until 5 do println(i)  // New syntax
for i <- 0 until 5 yield 2*i
for i <- 0 until 10
  if i%2 == 0
  ii = 2*i
yield ii

val i = 10
if (i < 10) println("yes")        // Original syntax
else println("no")
if i < 10 then println("yes")     // New syntax
else println("no")