We don’t really use Haskell and PureScript together. Rails backend calls Haskell services on one side and renders PureScirpt UI on the other, but services do not interact with UI directly.As far as using Haskell and PureScript simultaneously and comparing with each other, my experience has been mostly in favour of PureScript. Even though PureScript lacks many advanced features of Haskell (personally, the one I miss the most is type applications), it feels much more self-consistent and “solid”. I found myself enjoying programming in PureScript quite a bit more than in Haskell. Not to mention the glorious extendable ad-hoc records.