I ran into this today, and am wondering if there's any chance the Writer could work in future versions?
In my case, I need to control the precision of Doubles in a certain data structure, when being output to JSON. I could use the default reader, but now if I need to make a full Format, it brings up the question as to how do I proxy from the Format to the default reader...
Also, since we're working with implicits there's no compiler error when the Writer doesn't kick in. It just doesn't.
So in short: is there hope this would get "fixed" in later Spray-son versions (I'm on 1.3.2).
Link to SO entry discussing this: