Adding a list of variable values to a list in Lisp

Question

This is my first post so I apologize if I'm too vague or haven't done this correctly!

So I have an empty list L1 and two variables x and y which can be anything.

Say for example x = 10 and y = 20.

I would like the list L1 to start with x, and then I have a WHEN loop that add's y to the list every time it loops but I can't seem to get the list in the format I would like.

I currently have:

(let ((L1 x)))                  ; Adds x to the list

(loop

  (when (> n 10) (return))      ; While n < 10, add's y to the list.

  (setq L1 (list L1 y))

  (incf n)))

Which returns:

(10 20)
((10 20) 20)
(((10 20) 20) 20)
((((10 20) 20) 20) 20)
(((((10 20) 20) 20) 20) 20) ...

However I would like it to return:

( (10) (20) )
( (10) (20) (20) )
( (10) (20) (20) (20) )
( (10) (20) (20) (20) (20) )
( (10) (20) (20) (20) (20) (20) ) ...

Any ideas how I could do this?

Any help would be much appreciated!

uselpa · Accepted Answer · 2014-01-01 14:48:23Z

2

For example:

(defun test ()
  (let ((x 10) (y 20) (n 10))
    (cons (list x)
          (loop 
            for i from 1 to n
            collect (list y)))))

then

(test)
=> ((10) (20) (20) (20) (20) (20) (20) (20) (20) (20) (20))

or

(defun test ()
  (let ((x 10) (y 20) (n 10))
    (cons (list x) (make-list n :initial-element (list y)))))

answered Jan 1, 2014 at 14:48

uselpa

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2 Comments

user3151321 Over a year ago

Okay great, thanks! How do I set the list in your first example to L1?

uselpa Over a year ago

(setq L1 (test)) or (setq L1 (cons (list x) ...).

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