Defining a closure is straightforward as it derives from the way a function can be defined:

let adder = |a, b| {
  return a + b
}

At runtime, a closure is an instance of java.lang.invoke.MethodHandle. This means that you can do all the operations that method handles support, such as invoking them or inserting arguments as illustrated in the following example:

let adder = |a, b| {
  return a + b
}
println(adder: invokeWithArguments(1, 2))

let addToTen = adder: bindTo(10)
println(addToTen: invokeWithArguments(2))

As one would expect, this prints 3 and 12.