(apply case '(...))

[Dmi]

Code: Select all

(eval '(case 1 (1 "a"))) => "a"
(apply case '(1 (1 "a"))) => nil

What is the difference?

[Lutz]

You can use 'apply' only on normal functions evaluating their arguments. In 'case' the parenthesized terms are never evaluated but broken up by 'case' directly to access the innerts. In LISP lingo functions which do not evaluate their arguments are called special functions or special forms because they do not follow the normal evaluation rules.

It is the same as doing:

(apply dotimes '((x 10) (print x))) => fails
;or
(apply setq '(x 10)) => fails

Lutz

ps: I realize this should be mentioned in the documentation of 'apply'

[Dmi]

Thanks!