BTW, could indent of define-peg-rule be changed from 1 to 2:

------------------------------------------------------------
(defmacro define-peg-rule (name args &rest pexs)
  "Define PEG rule NAME as equivalent to PEXS.
The PEG expressions in PEXS are implicitly combined with the
sequencing `and' operator of PEG grammars."
  (declare (indent 1))
                  ^^^ to 2
------------------------------------------------------------

Currently the indentation of define-peg-rule looks strange:

------------------------------------------------------------
(define-peg-rule t--comment ()
		 hello
		 world
		 ...)
------------------------------------------------------------

By using (setf (get 'define-peg-rule 'lisp-indent-function) 2),
It looks better:

------------------------------------------------------------
(define-peg-rule t--comment ()
  hello
  world
  ...)
------------------------------------------------------------