(ns my.project
  (:require [ring.util.validators :refer :all]))

; The functions return validators, so we need to create
; them and then execute them.

((param-exists? :foo) {:params {}}) ; => false

((param-int? :foo) {:params {:foo "123"}}) ; => true

(defn my-handler [req]
  ;; does something incredible, of course
  )

(with-validations 
  #'my-handler
  (param-exists? :foo) "You need to specify a foo"
  (param-int? :bar) "Bar needs to be an integer"
  :on-error
    (fn [message e & args]
      ;; create error response
      ))

(param-exists? :name)
(param-int? :name)
(param-long? :name)