Detects if two strings are one edit away

one-edit-away.clj

(ns slifin.tdd2
  (:require [hyperfiddle.rcf :refer [tests]]))

(defn one-edit-away? [a b]
  (cond (= a b) true
        (> (Math/abs (- (count a) (count b))) 1) false
        (= (first a) (first b)) (recur (subs a 1) (subs b 1))
        (and (= (count a) (count b))
             (= a (str (first a) (subs b 1)))) true
        (and (> (count a) (count b))
             (= a (str (first a) b))) true
        (and (< (count a) (count b))
             (= a (subs b 1))) true
        :else false))

(tests
  (one-edit-away? "" "") := true
  (one-edit-away? "a" "") := true
  (one-edit-away? "" "a") := true
  (one-edit-away? "aa" "") := false
  (one-edit-away? "" "aa") := false
  (one-edit-away? "rasp" "rap") := true
  (one-edit-away? "aa" "aaa") := true
  (one-edit-away? "snap" "snip") := true
  (one-edit-away? "sni" "snap") := false)