I think you’re missing the point, @gregvaughn, that I’m trying to make as I was using an arbitrary example instead of constructing a real list that cannot be rewritten by a mere list comprehension.
The point is to construct lists with several different optional elements, each with its own condition (which occurs in my code base). Right now we either reject nil elements afterwards or flatten the overall list. It’s easy if everyone agrees how to handle optional elements.
My real example is data used describing steps in a protocol tester, which would look more like this:
[ < ... data representing step 1 ...>,
< ... data representing step 2 ...>,
< ... data represening optional step 3 ...>,
< ... data representing step 4 ...>,
< ... data represening optional step 5 ...> |
< ... data representing further test steps ...> ]
|> Enum.reject(&is_nil/1)
Each of these data structures is generated by calling a function to make the respective step.
If there was a way to construct such lists without having to filter or flatten them, it would be a boon in several places, but none of them really offer themselves for a list comprehension unless I missed your point.
