On Thu, Sep 22, 2016 at 12:35 PM, אלעזר <elazarg@gmail.com> wrote:

In such a hypothetical future world we might come to allow, e.g. `Sequence[#CustomThing]` where some general lazy facility or indirection is indicated by the '#' (just a placeholder for this comment, not a proposal). But if that comes about, it should be available everywhere, not only in annotations.

I generally agree, but this future world must be very far and has many consequences, whereas the story of annotations is special in that it's not actually an expression, to the reader.

The CPython developers (of whom I'm not one, but I've followed them closely for 18 years) place a high value on simplicity in the parser and interpreter. Adding a new custom type of thing that is an "annotation object" would be a special case with a high burden to show its utility.

My feeling is that this burden is actually lower for a new "delayed eval object" that might conceivably be added at a syntax level. In some sense, this would add just as much complexity as a new annotation object, but it would be something that applies many places and hence perhaps be worth the added complexity.

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