Why separate the recursive and non-recursive constructors?

[andrejbauer]

What is the purpose of separating the recursive and nonrecursive constructors? This should not be necessary. Also, where is the notion of "nonrecursive" and "recursive" constructor defined?

[nmvdw]

In hindsight it wasn't necessary. When I first thought of the construction, I separated them in order to prevent duplicates of the nonrecursive constructors. But in hindsight I needed to add coherencies anyway, and by doing that also for the nonrecursive constructors, I think it can be simplified.