23 Collection if elements

A collection literal can include an element only when a condition holds.

main() {
  Boolean includeExtra = false
  List<String> steps = [
    "read",
    if (includeExtra) "inspect",
    "run"
  ]
  printLine(steps.size())
  printLine(steps[1])
}

Expected output:

2
run

Here includeExtra is false, so inspect contributes no element at all; run becomes index one. This is different from an ordinary if expression that chooses one of two values.

Try it: Set the flag to true and predict the list size and index-one item.

Precise rules: Reference.