On Mon, Nov 10, 2014 at 10:25 AM, Greg Weber
What is the goal of this project? To pretty-print output? Or to be a slightly friendlier version of Show? To put it another way, what happens with more complicated structures? As an example, what should the output be for this type [[String]] ?
I've long used a Pretty class, which outputs a Doc from a pretty printing library. That way it can be flattened into one line or wrapped, depending on context. Most of the readability comes from the layout, and the rest comes from how I can omit "less important" data or use non-haskell syntax (e.g. {k: v} for maps). So for me a Display class that doesn't include layout wouldn't be very useful. I include all data in Show (and usually derive it), which means that it's valid syntax and I automatically parse and then format it with Language.Haskell.Pretty. I don't know if this is applicable to a general purpose Display class, because then it would have to pick a pretty printing library, which means it's making choices about layout and formatting, which means it's not really universal. E.g. I currently use HughesPJ but modified to avoid piling up on the right margin, but having been meaning for a long time to switch to an indentation based formatter that uses Text. Also, I use the showList hack. It works.