diff-path.janet

(defn diff-path
  [left right]
  (var i 0)
  (var done false)
  (def [shorter longer]
    (if (<= (length left) (length right))
      [left right]
      [right left]))
  (for j 0 (length shorter)
    (when (not= (get left j) (get right j))
      (set done true)
      (set i j)
      (break)))
  (cond
    (not done)
    [shorter (string/slice longer (length shorter))]
    #
    (= 0 i)
    ["" nil]
    #
    [(string/slice shorter 0 i) ""]))

(comment

  (diff-path "/usr/include"
             "/usr/include/fstab.h")
  # =>
  ["/usr/include" "/fstab.h"]

  (diff-path "/tmp" "hello")
  # =>
  ["" nil]

  (diff-path "/etc/motd" "/etc/issue")
  # =>
  ["/etc/" ""]

  )