snoyberg/mono-traversable — pull request #23 by snoyberg (2014-02-02 08:11:55+00:00)
Title: Minlen

Here's the basic idea of having a `newtype` wrapping with type-level naturals tagging the minimum known length of the contained data structure. I then expressed the current NonNull API in terms of this new module. I'm not convinced that this is worth the added complexity, but it's at least worth considering IMO.