On Tue, Feb 3, 2009 at 11:26 AM, Mark Volkmann <r.mark.volkm...@gmail.com> wrote: > > Now I remember what I was thinking about. This isn't so much a > difference between macros and functions as it is a rule about > something you cannot do in a macro. Quoting from "Programming Clojure" > ... > > "You cannot write a macro that expands to any of the syntactic sugar > forms ... For example, you cannot write a macro that > expands to (Math/PI)."
Hm... (defmacro pi [] 'Math/PI) ==> #'user/pi (macroexpand '(pi)) ==> Math/PI (pi) ==> 3.141592653589793 (defmacro strlen [s] `(.length ~s)) ==> #'user/strlen (strlen "hello") ==> 5 (defmacro mydoc [s] `(:doc ^#'~s)) ==> #'user/mydoc (macroexpand '(mydoc doc)) ==> (:doc (clojure.core/meta (var doc))) (mydoc doc) ==> "Prints documentation for a var or special form given its name" That's a whole lot of sugar that all seems to work ok. Is there some other syntactic sugar form that does not work? Perhaps he's referring to actually producing reader macro usages, like this: (defmacro mydoc2 [s] `(:doc ~(symbol (str "^#'" s)))) ==> #'user/mydoc2 (macroexpand '(mydoc2 doc)) ==> (:doc ^#'doc) (mydoc2 doc) ==> java.lang.Exception: Unable to resolve symbol: ^#'doc --Chouser --~--~---------~--~----~------------~-------~--~----~ 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 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 -~----------~----~----~----~------~----~------~--~---
