Do statement

do <statement> until(<expression>)

The statement (which can also be a block) is executed until the expression is true. The statement is executed at least once. Be careful with your do loops. You can easily make them loop forever, in which case your game will hang and not react to any user input anymore.

Example
The following program tries to place the current object at a free position (this is about the same as the action to move an object to a random position).

{
  do
  {
    x = random(room_width);
    y = random(room_height);
  }
  until (place_free(x,y))
}