monad-statement-abstractor.lisp

(define-statement-abstractor (monad m)
  (:rules
    (val ((name expr) rest) `(let ((,name ,expr)) ,rest))
    (get ((name expr) rest) `($ (monad-bind m) ,expr (fn (,name) ,rest)))
    (:else (expr rest)
      (let ((arg (gensym)))
        (if rest
            `($ (monad-bind m) ,expr
                (fn (,arg) (declare (ignore ,arg)) ,rest))
            expr))))
  (:whole (expr)
    `(let ((*monad* m)) ,expr)))