Doing a safe casting is as simple as using the cast keyword with the syntax cast(variable, Type). Therefore, you can do:

var a : A;
var b : B;
b = cast(a, B);

This will work if a is in fact an instance of B. If it's not, you will get an error at runtime.

You can do an unsafe casting by using the cast keyword in another way. If you just write cast followed by a variable or a value, you can use it as any type. So, for example, the following will compile:

var i : Int;
i = cast "Hello";

Keep in mind that although this code will compile, it is absolutely possible that depending on the target, it will fail at runtime.

It's also possible to completely deactivate type checking in a block of code. To do that, you will use the untyped keyword:

untyped { myVar.doSomething();}

However, keep in mind that although it will compile, it...