Sean Barnett

I have written this post as a quick reference to remind me how to handle error unions, optionals, and the combination of an error union with an optional.

Error Union

const blah = try callFunction();

const blah = callFunction() catch 0;

const blah = callFunction() catch |error| switch (error) {
    error.OutOfMemory => return,
    else => 0,
};

if (callFunction()) |value| {
    use(value);
} else |error| {
    handle(error);
}

Optional

const blah = callFunction() orelse 0;

const blah = callFunction() orelse return;

if (callFunction()) |the_value| {
    use(the_value);
} else {
    defaultAction();
}

Combined Error Union with Optional

while (try callFunction()) |the_value| {
    handle(the_value);
} else |the_error| {
   handle(the_value);
}

Note: need to test this wrt the try.

if (callFunction()) |the_value| {
    handle(the_value);
} catch |the_error| {
    handle(the_error);
} else {
    defaultAction();
}

Note: no idea if this works. #Zig