Usage instructions

[alphashuro]

How is this meant to be used? A description or example would be great to add to the docs or README.

[garyb]

It's not really meant to be used as-is, but rather as a base point to build other stuff on top of, but yeah it is lacking in documentation. I'm not too sure how to approach it really as it is very abstract.

https://github.com/garyb/purescript-codec-argonaut and https://github.com/garyb/purescript-codec-json are built on it (both libraries are very similar, just a differently underlying type, with json being the newer type).