-scala: while -> recursive

WhileLoop.scala

def `while`(condition: => Boolean)(command: => Unit): Unit = if (condition) {
  command
  `while`(condition)(command)
}

var i = 10

`while`{ i = i - 1; i > 0 } { println(i) }

Make your own while loop via recursion.

Please note that you need to call expression in the second parentheses by name, otherwise you evaluate it only once.

Not a lazy expression

command: Unit

Since (command: => Unit) we could do not pass an expression into the while

`while` { i = i - 1; i > 0 } {}

Compiler will add a Unit literal () implicitly to { () }. And it is just fine.