On Aug 13, 2009, at 3:35 PM, Bradbev wrote:
> > What is the main point of reader macros? Is it so you can define your > own short-hand syntax, or is it the ability to get more direct access > to the reader? > If it is the first point, then I'd be happy to not have them - to me > shorthand doesn't buy much. > If it is the second point then why not simply have the reader pipe raw > text into a reader macro? > Ie, usage would be like > (def-reader-macro pass-through [raw-string] > (read-string raw-string)) > > Usage would be (pass-through (+ 1 2)). The pass-through call would be > given "(+ 1 2)" in the raw-string argument and must return a value > that can be eval'd. > > More complex "reader" macros could be (infix x + y + z / 3). I think you can already do that with regular macros. I'm under the impression reader macros usually have to be prefixed with #, like #(foo %) which expands to (fn [x] (foo x)) or something like that. I can't find the common lisp units package I was talking about, but if it were perfect it would have worked something like Frink: http://futureboy.us/frinkdocs/ So you could do something like (+ 1m 2m) and have it give you back 3m, and if you did (/ 10m 5s) it would give you back 2m/s, and blow up if you tried to do (+ 1m 2m^2). It would be difficult to do such a thing unobtrusively without a reader macro. The other project I had experience with, CL-SQL, I think having a reader macro was sort of an abuse; it doesn't matter much if you have to put a call around your SQL or even stick it in quotes. Especially because it's unclear to me what value you should get from reading an SQL expression other than a string, unless it's going to blow up when you have a syntax error at compile time, but as an abstraction layer it certainly didn't have enough information to do that correctly at compile time. — Daniel Lyons --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
