let-bail.lisp

(defmacro let-bail (bindings &rest body)
  (if (null bindings)
    `(progn ,@body)
    (destructuring-bind ((&whole binding symbol value &optional return-value)
                         &rest more-bindings)
        bindings
      (if (eql symbol 'bail-when)
        `(if ,value ,return-value (let-bail ,more-bindings ,@body))
        `(let (,binding) (let-bail ,more-bindings ,@body))))))

(let-bail ((x (random 100))
           (bail-when (oddp x) 'what)
           (y (1+ x)))
   (list x y))