Yeah, I will try and have a look.  I had posted the patch, because the test looked like a bit of a larger chunk of work ;).

> And I'm surprised that you're surprised :)

:).  I am coming from a completely different angle, probably.  Just if you are curious, I use a from-spec like API (not public yet) in NumPy and dynamic use seemed natural/logical in that use-case, e.g.: https://github.com/numpy/numpy/blob/c92864091e5928d92bc109d1505febe35f3909f1/numpy/core/src/multiarray/convert_datatype.c#L2434

But, I am trying to understand the preference for static better.  There is probably something to learn or even important I am missing.


> And I have some plans to make static specs useful in type checking, since we can assume that types made from the same spec share the memory layout.

(I don't understand how it is useful, unless you reuse slot structs?)
It sounds interesting, but even static does not guarantee constant unless the user indicates it through a flag?
Maybe you could achieve this by figuring it out by inspecting/comparing content rather than using the spec pointer(s)? (More complex, but also more powerful?)