Hi Meikel, That's what I original thought I might have to do. But it seemed overly complicated. Perhaps there's no way around it.
I have a small question about the "with-bindings" function that you used. That one establishes dynamically scoped variables. Can't there be another Clojure function that provides lexically scoped variables? I actually don't know of any lisp/scheme system that provides a way to introduce lexically scoped variables at runtime. Do you know if there's a fundamental reason against doing so? -Patrick On Feb 10, 9:27 am, Meikel Brandmeyer <m...@kotka.de> wrote: > Hi, > > On 10 Feb., 14:58, CuppoJava <patrickli_2...@hotmail.com> wrote: > > > That's an awesome solution Meikel! > > You are welcome. :) > > > I forgot to specify that I want the bindings to have lexical scope > > only. But I think I can get that to work easily by modifying your > > solution. > > Haha. In fact that was my first impulse. But then I saw the (def a) > and read "bind" and changed my interpretation to dynamic scope. > > Lexical scope is much harder. The only "simple" solution, I see at the > moment, is walking the body of bind-later and do substitution. This is > in general ugly, but the only thing I can think of at the moment. This > is a (very) rough sketch, but you should get the key idea. > > (declare do-bind) > > (defn magic-walk-fn > [form locals db env] > (if (seq? form) > (let [[f & args] form > args (map magic-walk-fn args)] > (if (when-not (contains? env f) > (= #'do-bind (resolve f))) > `((fn [~locals] ~@args) ~db) > `(~f ~@args))) > (else-do-other-walking-magic form))) > > (defmacro bind-later > [bindings & body] > (let [db (gensym "deferred-bindings") > locals (vec (take-nth 2 bindings)) > values (vec (take-nth 2 (next bindings)))] > `(let [~db ~values] > ~@(map #(magic-walk-fn % locals db &env) body)))) > > Note that do-bind is just a dummy to identify the correct forms to > transform. > > Sincerely > Meikel -- 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
