The talks* Make Impossible States Impossible from Elm Conf 2016 * Make Data Structures from Elm Europe 2018 * Elm Radio Episode 2: Intro to Opaque Types

Dealing with Impossible States* Building up a "truth table" of possible states (see Evan's guide Types as Sets) * Which rows are invalid? * Create a new type with only the valid ones possible

More references* elm-css * Tereza's line-charts package * Tereza's elm Europe talk * elm-graphql * Gilded rose live stream * Snapshot testing (also called Approval Tests) * Jeremy Fairbank's Boolean Blindness talk