Escalier introduces the idea of mutable references. By default an immutable reference of type T will be equivalent to type Readonly<T>.
An object type T can contain a mix of readonly and mutable fields. A binding mut x: T allows x to mutate all fields except readonly fields and call all methods on T including those with mut self: Self as the receiver. In TS this would mean that Readonly<Set<T>> == ReadonlySet<T>, Readonly<Map<T>> == ReadonlyMap<T>, etc. which currently isn't the case.
Readonly<T> makes all properties readonly and removes all methods with mut self: Self as the receiver. This means that T is assignable to Readonly<T> (aka T is a subtype of Readonly<T>).
Given the binding x: T, i.e. x is not mutable, typeof x should return Readonly<T>.
Escalier introduces the idea of mutable references. By default an immutable reference of type
Twill be equivalent to typeReadonly<T>.An object type
Tcan contain a mix of readonly and mutable fields. A bindingmut x: Tallowsxto mutate all fields except readonly fields and call all methods onTincluding those withmut self: Selfas the receiver. In TS this would mean thatReadonly<Set<T>> == ReadonlySet<T>,Readonly<Map<T>> == ReadonlyMap<T>, etc. which currently isn't the case.Readonly<T>makes all properties readonly and removes all methods withmut self: Selfas the receiver. This means thatTis assignable toReadonly<T>(akaTis a subtype ofReadonly<T>).Given the binding
x: T, i.e.xis not mutable,typeof xshould returnReadonly<T>.