2009/12/20 Mike K <mbk.li...@gmail.com>: > On Dec 19, 8:27 pm, Sean Devlin <francoisdev...@gmail.com> wrote: >> :else was chose because it is simply not nil, and therefor always true. > > I suspected something along these lines soon after I posted. I did > some more experimenting and discovered that :foo will work just as > well as :else. So if I understand correctly, :else is not even > defined in the language anywhere. Like :foo, it springs into > existence when I first mention it, and it evaluates to true by virtue > of being a keyword. Cond exploits this behavior for free.
Right. :else is just a convention. I believe it's borrowed from Scheme. As pointed out by ataggart, anything that's logically true would work just as well. > This is in contrast with, e.g., the ns macro, which presumably would > have to explicitly match against keywords such as :use or :require to > implement the proper semantics. Yes, because the ns macro treats them as tokens in its mini-language instead of just something that's logically true. i.e. their value matters. Not just whether or not they can be treated as "true". -- Michael Wood <esiot...@gmail.com> -- 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
