Option Values

Introduction

This proposal adds a standard Option union type to model values that may be present or absent. It defines the @AnyOption attribute for marking option unions.

Syntax sugar for working with optional values (?., ??, T?) is covered separately in ZE-019 Result and Option Sugar.

Motivation

Zirric currently relies on ad-hoc conventions for missing values. A canonical Option type helps communicate intent and enables tooling to recognize optional flows consistently. By separating the type definitions from the syntax sugar, this proposal focuses on the foundational types.

Proposed Solution

Define an Option union with Some and None variants and a marker attribute.

attr AnyOption {}

@AnyOption()
union Option {
    data Some {
        value
    }

    data None
}

Usage

fn findUser(id: Int) -> Option {
    // returns Some(user) or None
}

const result = findUser(42)
switch result {
case Some(user):
    // use user.value
case None:
    // handle missing
}

Custom option types can be defined for specific domains:

@AnyOption()
union PersonOption {
    Person
    None
}

Detailed Design

@AnyOption

The @AnyOption attribute is a marker applied to union types. It signals that the union represents an optional value — one variant for presence and one for absence. This attribute is used by ZE-019 to enable syntactic sugar.

Option

The standard Option union has two variants:

• Some { value } — the present value, wrapping the inner value.
• None — the absent value, a data type with no fields.

Changes to the Standard Library

Alternatives Considered

• Using null or none literals — makes optional flows implicit and harder to check.
• Reusing Result — conflates absence with failure. Result (ZE-008) is for errors, not absence.

Acknowledgements

• Influenced by Swift’s Optional and Rust’s Option<T>.
• Syntax sugar for option values is defined in ZE-019 Result and Option Sugar.