How can I get Clojure :pre & :post to report their failing value?

Question

(defn string-to-string [s1] 
  {:pre  [(string? s1)]
   :post [(string? %)]}
  s1)

I like :pre and :post conditions, they allow me to figure out wh

Answer 1

Something like below where clojure spec is explaining the problem? This will throw an assertion error which you can catch.

 (defn string-to-string [s1] 
  {:pre [ (or (s/valid?  ::ur-spec-or-predicate s1) 
              (s/explain ::ur-spec-or-predicate s1)]}
  s1)