// Take x, return a function that adds x to its argument
fun makeAdder(x: int): (int) -> int =
    fun (y: int) ->
        x + y; // x is captured from the surrounding scope

let add1: (int) -> int = makeAdder(1);
let add2: (int) -> int = makeAdder(2);

// These assertions succeed in the interpreter, but fail in code generation!
assert(add1(40) = 41);
assert(add2(40) = 42)