maybe type about zig HOT 2 CLOSED

Better idea, no null pointer constant.

Instead we have a "maybe" type, perhaps by putting a question mark before another type, like this:

?*mut u8

This represents a tagged union which can either be None or a *mut u8 which is guaranteed to not be null. You could .unwrap() on a maybe type to resolve to a non-null type, or panic.

Also, a ?? operator which the left operand is a maybe type and the right operand is an expression which is of the unwrapped type. So you could for example:

fn func(x : ?bool) {
    let want_the_thing = x ?? true;
}

Now you have an optional boolean that has a default value of true.

Or:

fn create_a_thing() -> error {
    let thing = malloc(...) ?? {
        return Error.OutOfMem;
    };
    things.append(thing);
    return Error.None;
}

The right hand side of the ?? returned unreachable which is also legal.

from zig.

Alternate unpacking syntax ideas:

idea 1:

fn report_error(msg : string, maybe_additional_info : ?string) {
    report(str);
    ifunpack additional_info = maybe_additional_info {
        report(additional_info);
    }
}

idea 2:

fn report_error(msg : string, maybe_additional_info : ?string) {
    report(str);
    if let additional_info ?= maybe_additional_info {
        report(additional_info);
    }
}

from zig.