Hey Olaf, This is not an answer to your question, but I was reminded of Grace[0], which is a language with a "browser"[1] that allows you to type in terms and get back webpages based on those terms "automagically", which sounds like exactly what you need. I don't know how it's implemented, so I don't know if it is actually relevant to you, but it is worth noting that Grace itself is implemented in Haskell. Cheers, Georgi [0] https://github.com/Gabriella439/grace [1] https://trygrace.dev/ On 3/2/23 12:54, Olaf Klinke wrote:
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
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