Hi Konrad, many thanks. Thats stuff to ponder ;-)
(map (fn [s v] `(def ~s ~v)) '(a b c) '(1 2 3)) Thats impressive. I'm still, hm, puzzled. Nice example of something that can only be done with syntax-quote, and outside of a macro. (Or can this be done without syntax-quote, and I just dont see it?) Is there any predicate like (macro? my-macro), and, if we are at it (special-form? my-form) ? We could even generalise map with the thing you just described!(?) One more thing. I'm still heavily irritated about the expansion of '`(foo (bar ~a) ~b) >From clojure.org/reader, I learned "For Lists/Vectors/Sets/Maps, syntax-quote establishes a template of the corresponding data structure.", and from that, what I expected was (user/foo (user/bar a) b) Why is this so utterly wrong, and where should I know? Many thanks, alux On 3 Jun., 11:51, Konrad Hinsen <konrad.hin...@fastmail.net> wrote: > On 03.06.2010, at 10:36, alux wrote: > > > 1. I can use syntax-quote in the REPL, outside of a macro-definition. > > Is this of any use? Does this mean the REPL always macroexpands > > everything? > > Macro expansion is part of evaluation, whether at the REPL or elsewhere. > > Syntax quote is not macro expansion. It is a shorhand to write code that, > when executed, returns a specific form. It is more frequently used in macro > definitions, but you can use it anywhere. You can even look at the code it > generates: > > Clojure> '`(foo (bar ~a) ~b) > (clojure.core/seq (clojure.core/concat (clojure.core/list (quote > clojure.core/foo)) (clojure.core/list (clojure.core/seq (clojure.core/concat > (clojure.core/list (quote clojure.core/bar)) (clojure.core/list a)))) > (clojure.core/list b))) > > > 2. maxroexpand and macroexpand-1 dont extend macros in subforms. Is > > there anything that does? > > clojure.contrib.macro-utils/mexpandall > > > 3. Is there a way to use macros in higher order functions? Say along > > the lines of > > > (map def [a b c] [1 2 3]) > > No. Macros are not functions. BTW, def is a special form, not a macro. But > neither can be passed as a function. > > What you can do, however, is this: > > Clojure> (map (fn [s v] `(def ~s ~v)) '(a b c) '(1 2 3)) > ((def a 1) (def b 2) (def c 3)) > > Add a "do" in front, and you can pass it to eval: > > (eval (cons 'do (map (fn [s v] `(def ~s ~v)) '(a b c) '(1 2 3)))) > > > Btw, am I right that this might be possible in a lazy language? > > It's not impossible to imagine such a language, but I don't know of any. > > Konrad. -- 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
