Global objects

A global object is declared at module level with some fields:

~ foo { a: f64 }

fn bar() foo {
    println(foo.a)
}
fn baz() mut foo {
    foo.a = 42
}

The global object is created automatically if it doesn't exist already.
A global object outlives any other lifetime.

The globals function returns a list of all global objects:

fn main() {
    println(globals())
}

A global can be destroyed, but it will recreated when calling some function accessing it or using it:

fn main() {
    foo() // Creates global object `foo_object`
    destroy("foo")
    foo() // Recreates global object `foo_object`
}

~ foo_object {}
fn foo() foo_object {}

A global object can inherit from another global object:

~ rect { pos: [vec4], size: [vec4] }
~ button: rect { label: [str] }

When a global object only contains arrays as members, one can use the for-in syntax:

fn foo() mut button {
    for b in button {
         b.label = "click me!"
    }
}

Methods can be declared on global objects that can be used inside for-in syntax:

~ rect {
    pos: [vec4],
    size: [vec4],
    min() = pos
    max() = pos + size
}

fn foo() rect {
    for r in rect {
        println(r.max())
    }
}

Methods can also combine lists and scalar fields:

~ foo {
    a: f64,
    b: [f64],
    bar() = a + b
}

To insert a new item in a global object, one uses push syntax:

~ rect { pos: vec4, size: vec4 }

fn main() {
    foo()
}
fn foo() mut rect {
    push rect { pos: (0, 0), size: (0, 0) }
}

The super function returns the inherited global object of a global object:

fn super(global: str) -> opt[str] { ... }

The methods function returns a list of methods and their types:

fn methods(global: str) -> [{}] { ... }

The glob function converts a global into an ordinary object (read-only):

fn glob(global: str) -> opt[{}] { ... }

The issue provides no file, test, or entry point. First map how Dyon parses declarations, resolves names, manages lifetimes, inheritance, and built-ins, then define tests for the listed global-object behaviors; done means the examples and destruction/recreation semantics work.