What behavior would you expect?

[Chris Angelico]

On Fri, Feb 20, 2015 at 3:54 PM, Dan Sommers <dan at tombstonezero.net> wrote:
> if there are no
> values to return, then return an empty collection.

That one makes sense only if you were going to return a collection
anyway, though. If you were going to return a string, returning an
empty list on failure makes no sense. Hence the notion of returning a
"non-string".

ChrisA