Basically, I want the clojure equivalent of a clisp atom. In clisp, atom is true for everything that is not a cons cell. The closest match I found is creating a macro that returns true for everything that is not a list: clisp:
(atom 1) => true (atom '(1 2 3)) => false I hope that makes things clearer :) Andreas On 09/01/2011, at 10:36 AM, Ken Wesson wrote: > 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 -- “There is a strong correlation between being smart and being a nerd, and an even stronger inverse correlation between being a nerd and being popular” (Paul Graham) -- ********************************************************** Andreas Koestler, Software Engineer Leica Geosystems Pty Ltd 270 Gladstone Road, Dutton Park QLD 4102 Main: +61 7 3891 9772 Direct: +61 7 3117 8808 Fax: +61 7 3891 9336 Email: andreas.koest...@leica-geosystems.com ************www.leica-geosystems.com************* when it has to be right, Leica Geosystems Please consider the environment before printing this email. -- 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
