Dear Cafe, has anyone ever attempted (and maybe succeeded) in building dynamic forms using one of the Haskell web frameworks (Yesod,Servant,...)? By "dynamic" form I mean a form that changes the number of fields based on selections the user makes in other fields of the form. For example, say one has an algebraic data type data T = Number Int | Check Bool T A form for such a type would initially consist of radio buttons or a drop-down list with options "Number" and "Check" that lets the user select the constructor. When "Number" is selected, an <input type="number"> field is shown. When "Check" is selected, an <input type="checkbox"> is displayed next to another form of this kind. In the end, one would use the GHC.Generics machinery to generate forms for a wide range of algebraic data types. I've seen this in the Clean language's iTask library [1] and it's very convenient. Of course this would involve a lot of JavaScript like document.createElement() as well as book-keeping how to re-asseble the fields into a T value upon submission. At least the latter is already handled by libraries such as yesod-form. Olaf [1] https://cloogle.org/src/#itasks/iTasks/UI/Editor/Generic [2] https://github.com/haskell-servant/servant-swagger/issues/80