clojure.spec received significant attention at Clojure/conj 2016 including:

• Halloway's example for ETL,
• Rohner's Spectrum,
• Composing music with clojure.spec,
• Normand's drawing examples, and
• underpinings in Hickey's keynote.

Background on the rationale of clojure.spec is noted at https://clojure.org/about/spec . As noted it provices composability of entities with definitions similar to

• Swagger definitions, or
• normalizr schema

Since 1.9 is still fairly current so some of the examples are being pulled directly from the Clojure/conj conference slides.