Draft of a proposal for an Explicit Ownership Syntax

[JOTSR]

@mhofman

I don't see how you could introduce linear types in JS without requiring a new variable declaration to implement those semantics (let's call it linearLet). And that only solves the problem for holding an object reference.

It is more for the Explicit Reference Syntax but for declaration with the & (read write ref) sigil you can declare an exclusive reference:

let &exclusive = new Object()
let otherRef = &exclusive //ref error, value has already a mutable refrence
let @readOnlyRef = &ref //ref error, can't ref a reference (in the same scope, you can pass it as arg)

With clone/move you can limit scope access

let obj = /* any */
let obj2 = /* any */
function(clone obj, move obj2) {
 //obj is a clone and can be released with function
 //obj2 is moved and can be released with function
}

If you mix the 2 syntax you can clone the referenced value (clone &exclusive clone the value, not the reference to it).

@mhofman

How do you prevent duplicating a reference to the property of an object held in a linearLet?

It already was discuss in the reference topic but if it what you said, you can't return a reference since is need a cast to a non ref type (du to return keyword) which is forbidden by the syntax. If you return a moved object, it is like a new object you've got from the function call since the original object is dereferenced.

@mhofman

And how do you allow method calls on these objects (after-all methods are just function values held in the object's property)? Even if you somehow can get the method and invoke it, does the method call have access to the object as this?

As the object is cloned, there is no problem to call method, it is like a new declared object, the same for moved object but I don't see the issue since the object is not re-referenced in another scope. It has no influence on the lifetime.