HTTP and character encodings

[Henning Thielemann]

On Mon, 10 Sep 2012, Ganesh Sittampalam wrote:

> tl;dr: I'd like to remove the String instances from the HTTP package.
>
> The HTTP library is overloaded on the type for request and response
> bodies; there are instances for String and both strict and lazy Bytestrings.

This instance was also kind of broken, because it used 
TypeSynonymInstances without need.