Allow lazy implementations to raise from intrinsically eager functions

[cbourjau]

Allow intrinsically eager functions (such as array.__bool__) to raise in lazy implementations. Closes#642

[rgommers]

Thanks @cbourjau. This looks like a good start. I added a few minor comments. Then, I think __complex__ should get the same note, right?

My main suggestion for more context is perhaps something that could go in a short design document on lazy/eager, that could be put under https://data-apis.org/array-api/latest/design_topics/index.html. That also gives us a place to add other future lazy evaluation related topics. I am happy to draft that as a follow-up to this PR; we can get this merged first to clarify things.

[cbourjau]

Thanks for the review! I addressed your comments as suggested.

[cbourjau]

Is there anything missing in this PR before it could be merged?

[rgommers]

Is there anything missing in this PR before it could be merged?

No, there isn't. My array API review bandwidth disappeared for a bit. In it goes, thanks again @cbourjau!

[rgommers]

My main suggestion for more context is perhaps something that could go in a short design document on lazy/eager, that could be put under https://data-apis.org/array-api/latest/design_topics/index.html. That also gives us a place to add other future lazy evaluation related topics. I am happy to draft that as a follow-up to this PR; we can get this merged first to clarify things.

I'll need to do this now.

[rgommers]

Follow-up in gh-708.