Re: [Chicken-users] unbound variable: or

[Michele La Monaca]

On Fri, May 29, 2015 at 3:10 AM, Jinsong Liang <address@hidden> wrote:
> Thank you Michele! This is a nice example.

Nice but maybe not very useful:

(apply-syntax or (#f (+ 1 2) (print "hello")))

is just a longer and more cumbersome version of

(or (#f (+ 1 2) (print "hello")))

A far more valuable macro is the following:

(define-macro apply-any
  (lambda (_ lst)
    (eval `(cons ',_ ,lst))))

(define l '(#f (+ 1 2) (print "hello")))
(apply-any or l)

=> 3

(let ((x 9)) (apply-any or '(#f (+ x 1) (print "hello"))))

=> 10

(apply-any + (list 1 2 3))

=> 6

Regards,
Michele