Visibility

Visibility determines which code may name a declaration or member. Pop provides three implemented levels:

Visibility	Accessible from
public	other Bubbles
internal	the same Bubble
private	the declaring module

For ordinary declarations, omitting a visibility modifier gives internal visibility:

function helper()
    -- available inside this Bubble
end

public function start()
    -- may form part of the Bubble's public surface
end

Use public intentionally for behavior or types that another Bubble should depend on. Keep implementation helpers internal or private so they can change without affecting callers.

Fields and methods on classes use the same visibility words:

public class Account
    private balance: Int = 0

    public function currentBalance(): Int
        return self.balance
    end
end

Here callers can ask for the balance but cannot assign the field directly.

The main entry point is a special case: for a directly built executable, its omitted visibility is accepted as the private program entry. Writing a public or internal main is not a way to expose an alternate entry.

export is recognized as a reserved word in this release but is rejected as a declaration modifier. Use public for source-level visibility.