Smart pointers instead of GC?

[Frank Bauer]

On Tuesday, 4 February 2014 at 22:30:39 UTC, Walter Bright wrote:
> That's just what I wish to avoid. Consider adding more pointer 
> types - the combinatorics quickly explode. Heck, just have two 
> pointer parameters, and you already have 4 cases.
>
> I wonder how Rust deals with this.

Rust does not have null pointers.

In cases where you want to mark an object of some type as having 
"no value", or being "null", you use a stdlib type Option<T>, 
which is basically a tagged union plus some static compiler 
guarantees:

enum Option<T> {
     Some(T),
     None
}

An Option<T> either contains a T (tagged 'Some' then) or nothing 
(tagged 'None').

If you have a function that takes an Option<T> you can also pass 
it a (pure, non-nullable) T by specifying Some(myT) as the 
parameter.