Postwalk expansion would break macros that inspect their argument forms for e.g. writing special-purpose queries, if they *also* adopt the symbols "and" and "or" for conjunction or disjunction. Korma's "where", for instance, does this; one can write
(select my-table (where (and (...) (...)))) And the "where" detects the "and". Arguably this is wrongheaded behavior from the get-go (it can be somewhat confusing and makes it necessary to use something like clojure.core/and within "where" if you want normal clojure-land "and" semantics), but it's a style of non-anaphoric macro that relies on receiving an unexpanded form. On Wed, Sep 4, 2013 at 9:27 AM, Zach Tellman <ztell...@gmail.com> wrote: > So "complete recursive expansion" is postwalk macroexpansion? It seems > like that could break anaphoric macros, and likely others. A macro has the > option of calling macroexpand-all on its own contents if it wants only > special forms, but it shouldn't be forced to take only special forms. > > Also, here's a sketch of how you could do symbol macros using Riddley: > https://gist.github.com/ztellman/6439318. Please let me know if I'm > missing something w.r.t. how symbol macros are done in tools.macros. > > Zach > > > On Wed, Sep 4, 2013 at 2:16 AM, Konrad Hinsen < > googlegro...@khinsen.fastmail.net> wrote: > >> ** >> On Wed, Sep 4, 2013, at 09:25 AM, Zach Tellman wrote: >> >> I'm not sure what you mean by "complete recursive expansion". Could >> you expand >> on that? >> >> Completely ;-) >> >> By complete recursive expansion I mean that you get a form that is fully >> reduced to >> the core language, i.e. it contains no more macro applications at any >> level. >> >> If you leave macro expansion to the compiler, it does it when it arrives >> at the >> macro during evaluation. Then it does a plain non-recursive macroexpand >> and goes on >> evaluating. Any macro thus has access to the unexpanded contents of its >> form, but >> not to what it eventually expands to. For many applications that's just >> fine, which >> is why this approach has been the default in the Lisp world for a long >> time. >> >> As for replicating the behavior of the compiler, I'd assert that >> unless &env is >> precisely what it would be without ahead of time macroexpansion, the >> compiler's >> behavior isn't being replicated. >> >> I agree. tools.macro predates &env, which is why it is not supported. >> Since I have >> never need &env support and nobody ever asked for it (before now), it's >> not there. >> I don't see any reason why it couldn't be supported. >> >> 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 >> --- >> You received this message because you are subscribed to a topic in the >> Google Groups "Clojure" group. >> To unsubscribe from this topic, visit >> https://groups.google.com/d/topic/clojure/a68aThpvP4o/unsubscribe. >> To unsubscribe from this group and all its topics, send an email to >> clojure+unsubscr...@googlegroups.com. >> >> For more options, visit https://groups.google.com/groups/opt_out. >> > > -- > -- > 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. > -- 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.
