composable-form | Build type-safe composable forms in Elm | Functional Programming library

The form library doesn't explicitly support what you're trying to do, but we can make it work!

Here's my example of how you can take JSON and create a form: https://ellie-app.com/bJqNh29qnsva1

Form.list is definitely the promising path. You're also exactly right that Form.list requires all of the fields to be of the same type. So let's start there! We can make one data structure that can hold them by making a custom type. In my example, I called it DynamicFormFieldValue. We'll make a variant for each kind of field. I created ones for text, integer, and select list. Each one will need to hold the value of the field and all of the extras (like title and default value) to make it show up nicely. This will be what we decode the JSON into, what the form value is, and what the form output will be. The resulting types looks like this: