[dwenzek]

I would not say this is incorrect as there is no definition of `a: condition`.

As being declarative is about expectations, one translation could be:

I expect that "either both a and the condition to be true, or b true and the condition false" once the computation done.

      a when: condition

      b when: not condition

[aatd86]

There must still be an assignment somewhere.

This is a definition after all.

c = a if condition else c = b

Whether c is implicit or not doesn't matter too much.

I think the comment you respond to is still correct.

[throwaway290]

You can say that declarative style is only constant assignment. It doesn't make sense to use = though because (unlike imperative style) assignment is all there is, in a way