Miles Sabin

Okey doke ... backlogged :-)

@Atry have you tried that alternative definition of `Witness`?

As an aside, a more idiomatic approach to the motivating problem would be something along the lines of, ```scala trait Document { trait Element def createElement(): Element def appendChild(element: Element):...

Could you try modifying the shapeless definition as you suggest and see what (if anything) breaks?

@diesalbla is this causing a problem for your build, other than the report from sbt-missinglink?

It looks to me as though sbt-missing link isn't aware of the internal compiler classes that shapeless uses. Does it have `scala-compiler.jar` on its classpath?

I don't think we have it. I think it would be useful :-)

We worked through a load of similar issues in shapeless 2 on Scala 2, and in the end people came to expect that shapeless's `Generic` would do the right thing...

Possibly related SO [Q&A](http://stackoverflow.com/questions/18468606/extractor-for-a-shapeless-hlist-that-mimics-parser-concatenation/18484716#18484716).

I think the problem is that in `g: G = GInt` the `: G` is treated as an ascription which widens the single type of `GInt` leaving `A` abstract.