One quick hint, since `intern` is a function with side effects (mutates ns state) I would use `run!` instead of `map` (which is lazy).
Cheers! poniedziałek, 5 października 2020 o 14:02:22 UTC+2 Bost napisał(a): > This is pure gold - your answers! Thanks a lot. So the take outs and key > ideas for me are: > > - The syntax quote '`', unquote '~' and I expect also the unquote splicing > '~@' can be nested. > - A global var doesn't need to be created by the `def` (in macro). Use the > `intern` function directly (and be aware of possible lazy evaluation). > - There's more to `macroexpand` than just the debugging. Think out of the > box!* > > At the first glance I like the "use `intern`" idea at most and I'll give > it a try it the following form: > (defn def-stuff [x] (intern *ns* (symbol x) x)) > (map def-stuff [...]) > This way, I naively hope, I can reason about it the functional-programming > way: > Just create a function and map it over something. No code generation > or expansion trickery involved. > > Again, thank you very much, I consider adding your examples to > https://clojuredocs.org/clojure.core/def > > Bost > > *as always :) > > > Le lun. 5 oct. 2020 à 13:02, Jeremy Heiler <jeremy...@gmail.com> a écrit : > >> Do you know about macroexpand? >> >> user=> (defmacro m1 [v] `(def (symbol ~v))) >> #'user/m1 >> First argument to def must be a Symbol >> user=> (macroexpand '(m1 "foo")) >> (def (clojure.core/symbol "foo")) >> user=> (defmacro m2 [v] `(def ~(symbol v))) >> #'user/m2 >> user=> (macroexpand '(m2 "foo")) >> (def foo) >> >> The trick here is that you need to convert v into a symbol when the macro >> is expanded, not at runtime. >> >> On Oct 2, 2020 at 3:37:52 PM, Rostislav Svoboda <rostisla...@gmail.com> >> wrote: >> >>> I have a problem with `def` in macros. I'd like to create a bunch of >>> following definitions: >>> >>> (def foo "FOO") >>> (def bar "BAR") >>> (def baz "BAZ") >>> >>> So I wrote a macro: >>> >>> user=> (defmacro def-stuff [v] `(def (symbol ~v) >>> (clojure.string/upper-case ~v))) >>> #'user/def-stuff >>> >>> And I'd like to do map this macro over a vector of strings: >>> >>> user=> (map (fn [n] (def-stuff n)) ["foo" "bar" "baz"]) >>> Syntax error compiling def at (REPL:1:14). >>> First argument to def must be a Symbol >>> >>> A little check indicates that everything should be fine: >>> user=> (symbol? (symbol "foo")) >>> true >>> >>> but it is not: >>> user=> (def (symbol "foo") "FOO") >>> Syntax error compiling def at (REPL:1:1). >>> First argument to def must be a Symbol >>> >>> ??? >>> Interestingly enough: >>> >>> user=> (defmacro def-stuff [v] `(def v (clojure.string/upper-case ~v))) >>> #'user/def-stuff >>> user=> (map (fn [n] (def-stuff n)) ["foo" "bar" "baz"]) >>> (#'user/v #'user/v #'user/v) >>> >>> Strangely enough a `v` gets (re)defined. >>> >>> To me it looks like the lexical-binding of macro-parameters is ignored >>> if there's a `(def <macro-param> ...)` inside this macro. >>> >>> Can anybody explain what's going on here please? Thanks. >>> >>> -- >>> You received this message because you are subscribed to the Google >>> Groups "Clojure" group. >>> To post to this group, send email to clo...@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+u...@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+u...@googlegroups.com. >>> To view this discussion on the web visit >>> https://groups.google.com/d/msgid/clojure/CAEtmmex6Kn%3DQ8AZ-AyYoZLpYVu7%2BWnX3u7vQBgydiA%2B1jUt9Rw%40mail.gmail.com >>> >>> <https://groups.google.com/d/msgid/clojure/CAEtmmex6Kn%3DQ8AZ-AyYoZLpYVu7%2BWnX3u7vQBgydiA%2B1jUt9Rw%40mail.gmail.com?utm_medium=email&utm_source=footer> >>> . >>> >> -- >> You received this message because you are subscribed to the Google >> Groups "Clojure" group. >> To post to this group, send email to clo...@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+u...@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+u...@googlegroups.com. >> > To view this discussion on the web visit >> https://groups.google.com/d/msgid/clojure/CAKL9L2kXoG-9psgnbNKtdRBsAW3si_bRCDFpwB50thmM610MKg%40mail.gmail.com >> >> <https://groups.google.com/d/msgid/clojure/CAKL9L2kXoG-9psgnbNKtdRBsAW3si_bRCDFpwB50thmM610MKg%40mail.gmail.com?utm_medium=email&utm_source=footer> >> . >> > -- 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. To view this discussion on the web visit https://groups.google.com/d/msgid/clojure/c5afc190-1bbd-40e6-a452-24012f0b807en%40googlegroups.com.
