I don't work much with extensible records myself, but maybe an easier solution is to invert it so the item variants are contained in a field: type Item = {

I don't work much with extensible records myself, but maybe an easier solution is to invert it so the item variants are contained in a field: type Item = { name: String, year: Int, kind: Kind } type Kind = Cd { artist: String } | Book { author: String } | Shoes { size: Float } https://ellie-app.com/mSVCN8dQqX8a1 https://ellie-app.com/mSVCN8dQqX8a1 Consider joining the Slack community: https://elmlang.slack.com https://elmlang.slack.com -- The #beginners channel is a great place to ask these kinds of questions.