Default instance for Display

[reactormonk]

Would be really convenient to have a default implementation for Display, so deriving (Display) is possible.

[snoyberg]

What sensible default could we have? The only thing I can think of is using Show, but it's not a good option because:

1. It goes via String, which defeats the high-performance goals of this typeclass
2. A Display instance is intended to be human readable, whereas a Show instance is intended to match up with Haskell syntax

[reactormonk]

1. Could be solved by reimplementing the Show logic with Text.
2. Couldn't there be a default on how to display a record of values? It doesn't have to obey any laws anymore, so how it'll look like is arbitrary.

[snoyberg]

It sounds like you're talking about creating a Generic-based implementation using the Utf8Builder type which takes a random stab at making something user-friendly. I'm not sure about that approach tbh, I think it's going to end up encouraging the creation of non-user-friendly instances.