Thank you all. I think this thread is pretty much close by now. I understand at least most of your concerns and I will take time to shape my idea.
I wanted to note one last thing, though, regarding my claim that annotations are not actually standard expressions: Guido had once expressed his concerns regarding the performance hit of using cast(), since it is not easily (or at all) optimized away. This performance hit should not be there in the first place, if the distinction between annotations and evaluatable expressions was kept - i.e. by allowing the attachment of annotations to expressions (as I believe was proposed several times). Now, I understand that there are very good reasons not to allow it; keeping the language simple and familiar would be my first guess - but note how the semantics of the "main" language is hindered by the complexities of its specification-related syntactic subset, which is not due, in my opinion. If you want to specify things, the syntactic hit is unavoidable, but the semantic hit is not. (BTW why isn't it written cast[T](exp) ?) Thank you again for this discussion Elazar
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