Ben, Thanks for the feedback... and I'm sorry it to so long to say thanks (I've been traveling).
In terms of the lack of being hygienic, I discuss that in the next paragraph in the blog post the OP took the macro from. But I really appreciate your thoughts on error messages. As I develop macros, I'll work hard to make sure the end users (who may not be me) get better feedback. Rock on. David On Fri, Jun 7, 2013 at 4:43 PM, Ben Wolfson <wolf...@gmail.com> wrote: > On Fri, Jun 7, 2013 at 12:30 PM, David Pollak < > feeder.of.the.be...@gmail.com> wrote: > >> >> >> >> On Fri, Jun 7, 2013 at 11:14 AM, Ben Wolfson <wolf...@gmail.com> wrote: >> >>> >>> >>> The macro (which IMO is terrible and shouldn't be emulated) >>> >> >> Why do you think the macro is terrible? >> > > It's unnecessarily unhygienic: > > user> (require '[clojure.core.match :refer [match]]) > nil > user> (defmacro match-func [& body] `(fn [~'x] (match [~'x] ~@body))) > #'user/match-func > user> ((match-func [s] x) 1) > 1 > user> ((match-func [[q s]] [q s]) [1 2]) > [1 2] > user> ((match-func [[q x]] [q x]) [1 2]) > nil > user> > > Proper use requires knowing how it's implemented, and its error messages > are opaque: > > user> (match-func [a s] s) > CompilerException java.lang.AssertionError: Pattern row 1: Pattern row has > differing number of patterns. [a s] has 2 pattern/s, expecting 1 for > occurrences [x], compiling:(NO_SOURCE_PATH:1) > > It wouldn't be hard to catch that error and alert the user before passing > it on to core.match/match. (Though, to be fair, lots of clojure macros seem > to take the view that enforcement of proper syntax is someone else's > problem.) > > (I also favor More Parens for grouping purposes; I think it's ugly and > hard to read when you write (match-func pattern1 action1 pattern2 action2) > and have them all mixed up together like that. But that also applies to > core.match itself, so. I will say that insofar as this is a macro for > defining functions, it would be better if the actions to be taken on > successful matches were wrapped in implicit dos, which is something that's > only possible if the pattern row/action pairs are themselves delimited by > parens or something paren-like.) > > -- > Ben Wolfson > "Human kind has used its intelligence to vary the flavour of drinks, which > may be sweet, aromatic, fermented or spirit-based. ... Family and social > life also offer numerous other occasions to consume drinks for pleasure." > [Larousse, "Drink" entry] > > -- > -- > 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 > --- > You received this message because you are subscribed to the Google Groups > "Clojure" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to clojure+unsubscr...@googlegroups.com. > For more options, visit https://groups.google.com/groups/opt_out. > > > -- Telegram, Simply Beautiful CMS https://telegr.am Lift, the simply functional web framework http://liftweb.net Follow me: http://twitter.com/dpp Blog: http://goodstuff.im -- -- 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 --- You received this message because you are subscribed to the Google Groups "Clojure" group. To unsubscribe from this group and stop receiving emails from it, send an email to clojure+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/groups/opt_out.
