Example of simple-check output when the input data are functions.

simple-check-fns.clj

(require '[simple-check.core :as sc])
(require '[simple-check.generators :as gen])
(require '[simple-check.properties :as prop])

(def gen-inc
  (gen/bind gen/pos-int #(gen/return (partial + %))))

(def gen-dec
  (gen/bind gen/pos-int #(gen/return (partial - %))))

(def gen-command
  (gen/one-of [gen-inc gen-dec]))

;; Starting at 5, is there a sequence of increments / decrements that
;; causes our value to become negative?
(def prop-always-positive
  (prop/for-all [commands (gen/list gen-command)]
    (let [combined-command (apply comp commands)]      
      (pos? (combined-command 5)))))

(sc/quick-check 100 prop-always-positive)
;; {:result false,
;;  :failing-size 3,
;;  :num-tests 4,
;;  :fail [(#<core$partial$fn__4190 clojure.core$partial$fn__4190@10c3db68>)],
;;  :shrunk {:total-nodes-visited 4,
;;           :depth 1,
;;           :result false,
;;           :smallest [(#<core$partial$fn__4190 clojure.core$partial$fn__4190@2a799171>)]}}

;; I'd love to have a better output than:
;; #<core$partial$fn__4190 clojure.core$partial$fn__4190@10c3db68>
;; Perhaps there is a way to annotate the generator with user-specified data?