No idea how common it is. It's never been my main work language but I've been using it at work for prototyping/scripting/automation/analysis etc for at least ten years now.

It looks like what I've done is most similar to https://www.parsonsmatt.org/2018/03/22/three_layer_haskell_c...

And I think this was the post that proposed tagless-final over free-monads: https://markkarpov.com/post/free-monad-considered-harmful.ht...