Approximate comparison of floating-point numbers for clojure.data/diff.

fuzzy_diff.clj

(ns fuzzy-diff
  "Approximate comparison of floating-point numbers for clojure.data/diff."
  (:require [clojure.data :refer [Diff]]))

(def ^:dynamic *fuzz* 0)

(defn fuzzy-float-diff [a b]
  (if (< (Math/abs (- a b)) *fuzz*) [nil nil a] [a b nil]))

(extend java.lang.Double
  Diff
  {:diff-similar fuzzy-float-diff})

(extend java.lang.Float
  Diff
  {:diff-similar fuzzy-float-diff})

;; examples:
;;
;; (require '[fuzzy-diff :refer [*fuzz*]])
;;
;; user> (diff {:a 1.2} {:a 1.200000001})
;; ({:a 1.2} {:a 1.200000001} nil)
;;
;; user> (binding [*fuzz* 1e-1]
;;         (diff {:a 1.2} {:a 1.200000001}))
;; (nil nil {:a 1.2})