halt return type gets in the way

[phrodo00]

Since halt doesn't return, it should return Nothing. This can be accomplished by throwing the result of java's halt (it won't actually get thrown because java's halt will do it first).

This will let us use halt inside of when and the like without affecting the type of the expression. (right now, since halt returns the exception, a when statement will change its type to Any for no good reason)

[Mee42]

On another note, could we have HaltException extend Exception instead of RuntimeException, so the compiler can smart-cast T? objects to non-nullable T objects in some places

ex:

val x :Int? = null
if(x == null)
    halt(400,"x is null")
x.toString()//and other methods, because x is of type Int not Int?```