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Comment by throwaway290 | Hacker News Reader

You can represent this

    if condition: a else: b

declaratively as

    a: condition
    b: not condition

This rephrasing does not work if "do" is in the picture, and turing-incomplete parsing becomes difficult.

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This is incorrect. You are not defining a or b. You are defining c as either a or b.

Declarative way: c = condition ? a : b

Imperative way:

    c = null
    if condition:
        c = a
    else:
        c = b

But in many imperative languages you would equally use a ternary operator? c = condition ? a : b

And in Python at least, it would be:

    if condition:
      c = a
    else:
      c = b

(i.e. no upfront declaration of c)

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

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.

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

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