I see it mainly as an answer to static types. Clojure (like most Lisps) places emphasis on dynamic types, for some valid reasons (https://lispcast.com/clojure-a

I see it mainly as an answer to static types. Clojure (like most Lisps) places emphasis on dynamic types, for some valid reasons (https://lispcast.com/clojure-and-types/ https://lispcast.com/clojure-and-types/). But there are certain undeniable benefits of static typing that you miss out on: documentation, and IDE hints. Spec, the way I see it, is a way to reclaim some of those benefits without giving up the dynamic paradigm. It also has some advantages over static type systems; most notably you can describe any arbitrary assertion, which makes it more expressive than regular types. You can also check things at runtime, which can be useful for validating foreign inputs that aren't available at build time. Personally I'm still a static-types person, but I get it. And if I used Clojure regularly, I'd be all over Spec.