53 Lambdas

A lambda creates a function value at the use site. Its parameter and result types follow the expected function type; its final expression supplies the result.

Integer apply(Integer transform(Integer number), Integer input) {
  return transform(input)
}

main() {
  Function<Integer(Integer)> twice = (number) {
    number * 2
  }
  printLine(twice(5))
  printLine(apply(transform: (number) { number + 3 }, input: 5))
}

Expected output:

10
8

Try it: Change number + 3 to number * 3 and predict the second line.

Precise rules: Reference.