"predicate-based data flow" is something I haven't heard before, what do you have in mind? I agree that clojure.spec2 can probably generate UI ... This gist is where Hyperfiddle DSL is roughly at right now but I think the Datomic schema definitions can be replaced by specs and the pull queries by s/select https://gist.github.com/dustingetz/96c928f755c736d2b525bb61a...