Elisp: Sequence. some, every (conditional exit)

(seq-some PRED SEQUENCE)

• Apply a function PRED to each sequence element in order.
• Exit loop when PRED return true. Return that value.
• If no result is true, return false.

🟢 tip: This is useful as functional programing style of doing a loop with break, especially when you need to know which element breaks the condition.

;; demo of seq-some
(seq-some
 (lambda (x)
   (if (eq 5 x)
       x
     nil
     ))
 [4 5 6])
;; 5

(seq-every-p PRED SEQUENCE)

• Apply a function PRED to each sequence element in order.
• Exit loop when PRED return false.
• Return true if every result is true, else false.

🟢 tip: This is useful as functional programing style of doing a loop with break, and you do not need to know which element breaks the condition.

;; demo of seq-every-p
(seq-every-p
 (lambda (x)
   (if (eq (mod x 2) 0)
       x
     nil
     ))
 [4 5 6])
;; nil