A simple prefix on FormAction

[yixe]

is there a simpler way to achieve a prefix on a simple form field?

viewStore.binding(keyPath: \.username, send: Profile.form)

i'd link to add a simple .prefix(10) to this field

[tgrapperon]

If I understand correctly, you can use a computed property if you want to continue using a binding reducer:

var userName10: String {
  get { username.prefix(10) }
  set { username = newValue.prefix(10) }
}

and use \.username10 in your binding.
I would personally implement this validation logic in a reducer though, but it's mostly a matter of taste and it depends on the complexity of your domain. I guess doing the validation in the accessor is OK in this simple case.