Polymorphic variants in Ur/Web July 29, 2012
This document explains how polymorphic variants in Ur/Web work. It was written because the official tutorial has no mention of them, the manual only devotes a paragraph to the topic, and there are some useful tricks for dealing with them that I picked up while wrangling with them in Logitext.
What are polymorphic variants?
Polymorphic variants may be familiar to OCaml users: they permit you to use the tags of variants in multiple types, and not just in the original algebraic data type a constructor was defined in. Instead having to keep names unique: