Testing whether lambda expression returns true for any list element
If you already have Common Lisp-derived functions in there, use CL-SOME instead:

(defun executable-in-path-p (executable)
  "Test if EXECUTABLE exists in path."
  (cl-some (lambda (path) (file-exists-p (concat (file-name-as-directory path) executable))) exec-path))


That's of course a little bit different than explicitly checking for t, but you shouldn't be doing that anyway in most cases (everything but nil is already true).