New to LISP

Hi all, I am very new to lisp. I have this function (adopted from vacuum agent problem)

(defun find-closest-in-grid (radar type pos-x pos-y)
(labels ((distance (x y)
(+ (abs (- x pos-x))
(abs (- y pos-y)))))
(destructuring-bind (width height)
(array-dimensions radar)
(let ((best nil)
((best-distance (+ width height))))
(loop for x from 0 below width
do (loop for y from 0 below height
do (loop for element in (aref radar x y)
do (when (eql (type-of element) type)
(when (<= (distance x y) best-distance)
(setf best (list x y))
(setf best-distance (distance x y))))))))
best)))


But i wish to convert to (defun find-closest-in-grid (radar type ) with only two parameters while keeping the remaining function the same. How should go about doing it

You mean you want the position to be global variables instead of parameters?

Yes David. Thanks for the great help.

Or you can take more functional approach and return a lambda function so instead of:

(defun find-closest-in-grid (radar type pos-x pos-y)
  (labels ((distance (x y) 
             (+ (abs (- x pos-x)) 
                (abs (- y pos-y)))))
    (destructuring-bind (width height) (array-dimensions radar)
      (let ((best nil)
            ((best-distance (+ width height))))
        (loop for x from 0 below width
              do (loop for y from 0 below height
                       do (loop for element in (aref radar x y)
                                do (when (eql (type-of element) type)
                                     (when (<= (distance x y) best-distance)
                                       (setf best (list x y))
                                       (setf best-distance (distance x y)))))))
        best))))

you write:

(defun get-find-closest-in-grid (pos-x pos-y)
  (lambda (radar type)
    (labels ((distance (x y) 
               (+ (abs (- x pos-x)) 
                  (abs (- y pos-y)))))
      (destructuring-bind (width height) (array-dimensions radar)
        (let ((best nil)
              ((best-distance (+ width height))))
          (loop for x from 0 below width
                do (loop for y from 0 below height
                         do (loop for element in (aref radar x y)
                                  do (when (eql (type-of element) type)
                                       (when (<= (distance x y) best-distance)
                                         (setf best (list x y))
                                         (setf best-distance (distance x y)))))))
          best)))))