On Sat, Jan 8, 2011 at 7:25 PM, Andreas Kostler <andreas.koestler.le...@gmail.com> wrote: > Ken, > Thanks for your reply. Is that about what you mean? > > (defmacro literal? [form] > (list 'if `(not (list? ~form)) true false))
Sort of, but that isn't quite going to work. It will expand to (if (clojure.core/not (clojure.core/list? <the-form>)) true false) That's not especially efficient; you can dispense with the if entirely and just use `(not (list? ~form)) and get the same results. But the results also won't be what you're hoping for. Put in (literal? (+ 2 3)) and you'll get true! That's because it will expand to (not (list? (+ 2 3))) which will evaluate to (not (list? 5)) and then (not false) and then true. 5 is not a list. The problem is that the list? test is happening at run time, not macroexpansion time. You'd need (defmacro literal? [form] (not (list? form))) which will simply evaluate to true or false depending. (literal? (+ 2 3)) will now expand to false, and that will evaluate to false. I'm not sure what use this is, though. I suppose you want to know if an argument to some more complex macro is literal or not, in which case (not (list? arg)) (OUTSIDE of your syntax-quotes, or unquoted) will do nicely, depending on your requirements. But do you want [1 2] and [(- 3 2) (+ 1 1)] to both count as literal, or only the former? What about [(count my-seq) (reduce + (map parse-int (line-seq rdr)))]? Do you want (quote (1 2 3)) to count as literal? -- You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
