As reference, here is what @bergey explained to me about the Backend architecture
<bergey> The key pieces of writing a Backend are an instance of the Backend
type class and one or more instances of the Renderable type class
[09:31]
<bergey>
http://hackage.haskell.org/package/diagrams-core-1.3.0.6/docs/Diagrams-Core-Types.html#g:16
<bergey> Typically, a Renderable instance for the Path type. [09:32]
<bergey> When writing the Backend instance, you get to pick some types. You
might pick that the Result type of rendering a Diagram is an IO ()
action which draws the Diagram. Or something more flexible, like
GLContext -> IO () [09:36]
The area for backends documentation in the
diagrams-core
explanation is missing.As reference, here is what @bergey explained to me about the
Backend
architecture