need some clarification on compile-time type vs. run-time type

[P T Withington]

On 2007-11-11, at 00:57 EST, Brendan Eich wrote:

> There are questions about exactly what strict mode analyses might be
> mandated as normative if an implementation supports strict mode. This
> may be clearer to Graydon and Cormac than to me, so I'd welcome their
> comments. For example:
>
>     function g(a_not_null: T!) ...
>
>     function f(a: T) {
>         if (a !== null)
>             g(a);           // no cast required?
>     }

IMO, mandating that level of analysis violates the spirit of the goal  
of permitting simple compilers.  You should use `type switch` if you  
want to avoid the cast (and guarantee no redundant runtime overhead).