@hackage / portray

This provides a single place to describe how a type should be formatted as pseudo-Haskell syntax, independently of the actual pretty-printing library (e.g. "pretty", "ansi-wl-pprint", or "prettyprinter") that will ultimately be used to render it. This means packages can cheaply provide integration with all pretty-printers by providing an instance of this class, without needing to depend on any of them (or their layout algorithms).

Of course, this comes at the cost of targeting a predeclared set of formatting choices. If there are any egregious omissions, we can always add more constructors.

This library is explicitly not intended to provide a way to express all documents; only a particular flavor of pseudo-Haskell syntax representing values and types.