There is nothing which would require me to use Clojure to check those things. For example... one can easily express all that in Common Lisp: https://www.lispw

There is nothing which would require me to use Clojure to check those things. For example... one can easily express all that in Common Lisp: https://www.lispworks.com/documentation/HyperSpec/Body/04_b.htm https://www.lispworks.com/documentation/HyperSpec/Body/04_b.... CL-USER 9 > (defun non-empty-string-p (string) (and (stringp string) (plusp (length string)))) NON-EMPTY-STRING-P CL-USER 10 > (deftype name-type () `(and string (satisfies non-empty-string-p))) NAME-TYPE CL-USER 11 > (deftype age-type () `(integer 18 120)) AGE-TYPE CL-USER 12 > (defun foo (age name) (declare (type age-type age) (type name-type name)) (print (list age name))) FOO also, avoiding SATISFIES: CL-USER 4 > (deftype name-type () `(and string (not (string 0)))) NAME-TYPE CL-USER 5 > (typep "hello" 'name-type) T CL-USER 6 > (typep "" 'name-type) NIL It then has assertions integrated with the condition system, which makes this easily checkable at runtime. SBCL has this extended with type declarations as assertions: http://sbcl.org/manual/index.html#Handling-of-Types http://sbcl.org/manual/index.html#Handling-of-Types Eiffel had promoted Design by Contract for a long time. > Cisco built their cybersecurity platform using Clojure. Cisco uses a lot of software. Your Clojure marketing attempts are getting silly.