(defun diff-strings (string1 string2)
  (uiop:with-temporary-file (:pathname path1 :directory "/tmp")
    (uiop:with-temporary-file (:pathname path2 :directory "/tmp")
      (alexandria:write-string-into-file string1 path1 :if-exists :supersede)
      (alexandria:write-string-into-file string2 path2 :if-exists :supersede)
      (let ((program (list "/usr/bin/diff"
                           (uiop:native-namestring path1)
                           (uiop:native-namestring path2))))
        (uiop:run-program program
                          :output :string
                          :ignore-error-status t)))))