Macro: WITH-REDUCER

Documentation

Locally bind NAME to a reducing function. The arguments FUNCTION and INITIAL-VALUE are passed directly to MAKE-REDUCER.

Source

(defmacro with-reducer ((name function &optional (initial-value nil))
                        &body body)
  "Locally bind NAME to a reducing function. The arguments
FUNCTION and INITIAL-VALUE are passed directly to MAKE-REDUCER."
  (with-unique-names (reducer)
    `(let ((,reducer (make-reducer ,function ,@(list initial-value))))
       (flet ((,name (&rest items)
                (if items
                    (dolist (i items)
                      (funcall ,reducer i))
                    (funcall ,reducer))))
         ,@body))))