http4s/http4s — pull request #113 by rossabaker (2014-12-08 19:45:27+00:00)
Title: Make EntityEncoder invariant

* Contravariant type classes are scarce both in standard lib and scalaz.
* [This WONTFIX](https://issues.scala-lang.org/browse/SI-2509) and ["the blight of contravariance" discussion](https://groups.google.com/forum/#!topic/scala-language/ZE83TvSWpT4) shed light on why not.
* It didn't really hurt at all to make them invariant.