Field defaults

Record and class fields may provide a default initializer:

public record Settings
    retries: Int = 3
    verbose: Boolean = false
end

When an aggregate is created in a context expecting Settings, omitted fields use their defaults:

function defaults(): Settings
    return {}
end

A caller may override either field:

function verboseSettings(): Settings
    return { verbose = true }
end

Defaults are evaluated at compile time. This guarantees that constructing a value does not hide an arbitrary runtime call and that the default is available consistently wherever the type is used.

The initializer can use literals, constants, and valid compile-time functions. It cannot read runtime state:

function currentRetries(): Int
    return 5
end

public record Invalid
    retries: Int = currentRetries() -- rejected: runtime-only call
end

Defaults do not make a field optional in the type-system sense. After construction, settings.retries is still an Int, not an Int?. A default only lets construction omit that field.

Use defaults for unsurprising values that are valid for every construction. Keep a field required when forcing the caller to choose makes mistakes less likely.