This patch is to use doctest v0.6.
In my environment, this patch works well. But this is just a sample implementation. Please review this carefully.
What I want is to use doctest v0.6. So, it's nice even if you support doctest v0.6 by yourself and reject this patch.
Using doctest v0.6.
@kazu-yamamoto it is important to restrict the version of doctest to < 0.7.
The next version of Doctest will print source locations on failing tests. This is an awesome feature (IMO), but it will sadly break the API again.
@sol thanks for the heads up. @kazu-yamamoto your change seemed ok, I did a bit of tuning on top of that and will upload this to hackage.