Passing a list of functions as an argument in common Lisp -
say there function f. want pass list of functions argument function f.
function f go through each function in list 1 one , apply each 1 2 integers: x , y respectively.
for example, if list = (plus, minus, plus, divide, times, plus) , x = 6 , y = 2, output this:
8 4 8 3 12 8 how implement in common lisp?
there many possibilities.
cl-user> (defun f (x y functions) (mapcar (lambda (function) (funcall function x y)) functions)) f cl-user> (f 6 2 (list #'+ #'- #'+ #'/ #'* #'+)) (8 4 8 3 12 8) cl-user> (defun f (x y functions) (loop function in functions collect (funcall function x y))) f cl-user> (f 6 2 (list #'+ #'- #'+ #'/ #'* #'+)) (8 4 8 3 12 8) cl-user> (defun f (x y functions) (cond ((null functions) '()) (t (cons (funcall (car functions) x y) (f x y (cdr functions)))))) f cl-user> (f 6 2 (list #'+ #'- #'+ #'/ #'* #'+)) (8 4 8 3 12 8) cl-user> (defun f (x y functions) (labels ((rec (functions acc) (cond ((null functions) acc) (t (rec (cdr functions) (cons (funcall (car functions) x y) acc)))))) (nreverse (rec functions (list))))) f cl-user> (f 6 2 (list #'+ #'- #'+ #'/ #'* #'+)) (8 4 8 3 12 8) cl-user> (defun f (x y functions) (flet ((stepper (function result) (cons (funcall function x y) result))) (reduce #'stepper functions :from-end t :initial-value '()))) f cl-user> (f 6 2 (list #'+ #'- #'+ #'/ #'* #'+)) (8 4 8 3 12 8) and on.
the first 2 readable, third 1 how rookie in first lisp course it, fourth 1 still rookie, after heard tail call optimization, fifth 1 written under cover haskeller.
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