Elminate Illegal States in Reason with Variants

The ability to express multiple options that are exclusive as a data structure is a powerful concept. To leverage it's full power it's requires some rethinking on how to model our data.

We are going use a simple UI example to rethink how to approach representing our state.

This lesson was highly inspired by Yaron Minky's advice to "make illegal states unrepresentable" in his talk Effective ML as well as Richard Feldman's talk Making impossible states impossible with Elm.