pass by shallow value flaw

// Implicit is the following {..} = import('stdlib');

// I'm assuming that Struct is able to read the last 'frame' and keep the values. Inner(value: Int): Inner = Struct; // I'm going to try to use a postfix reference notation so that T?(pointer to a nullable) // and T? (nullable-pointer) aren't ambiguous. // That is T? = T | null // That's typescript notation but I think I'll keep it. Outer(inner: Inner*, value: Int) = Struct;

// This could be just Mut(o) but that would imply that we could change o.inner, not just the value of *o.inner // Note: I don't think we should copy o to pass it to quack, only to create a new version to modify it, // but that might be an optimisation of COW semantics rather than the default semantics... not sure if it matters. quack(o: Outer): Outer & Mut(o.value) & Mut(o.inner->value) = { o.value += 1; o.inner->value += 1; o }

main(): Int { inner1 = Inner(0); // inner1 = {value: 0} outer1 = Outer(*inner1, 0); // outer1 = {inner: *inner1, value: 0} outer2 = quack(outer1); // outer2 = {inner: *inner1, value: 1}, inner = {value: 1} outer3 = quack(outer2); // outer3 = {inner: *inner1, value: 2}, inner = {value: 2}

println("outer1.value is", outer1.value); println("outer2.value is", outer2.value); println("outer3.value is", outer3.value); println("inner1.value is", inner1.value); 0 }

/* output: outer1.value is 0 outer2.value is 1 outer3.value is 2 inner1.value is 2 */