Help writing an emacs/lisp function Write a function that takes one parameter that is a list of numbers and returns true (t) if all the elements of the list are multiples of the first one and nil otherwise. This said, a list generated by the function make-multiples could be passed to this new function and the result should be true. On the other hand, show an example of a list that could not have been generated by the first function for which the result is still true.
Help writing an emacs/lisp function
Write a function that takes one parameter that is a list of numbers and returns true (t) if all the elements of the list are multiples of the first one and nil otherwise. This said, a list generated by the function make-multiples could be passed to this new function and the result should be true. On the other hand, show an example of a list that could not have been generated by the first function for which the result is still true.
Here's an Emacs Lisp function that takes a list of numbers as input and returns t if all elements of the list are multiples of the first element, and nil otherwise:
Code:
(defun all-multiples (lst)
"Return t if all elements in the list LST are multiples of the first element, and nil otherwise."
(let ((first (car lst)))
(every (lambda (x) (zerop (mod x first))) (cdr lst))))
The function first extracts the first element of the list and then uses every function to check whether all the remaining elements are multiples of this first element. The lambda function passed to every check, whether the remainder of the element divided by the first element, is zero, which is equivalent to checking whether the element is a multiple of the first element. The zerop function is used to test whether the result of the mod function is zero, which means that there is no remainder.
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