Hi, Recently encountered a weird issue, A def in if clause declared a var but left it unbound.
I encountered this issue when I was trying to implement something like "define a symbol if it is not defined yet". Naively I tried: (if (nil? (resolve 'foo)) (def foo 42)) ; Cannot use (def foo (if (nil? (resolve 'foo)) foo 42)) because foo might be macro I tried in repl and the result really surprised me: user=> foo CompilerException java.lang.RuntimeException: Unable to resolve symbol: foo in this context, compiling:(/private/var/folders/1h/vhl8yb657mjf3pchm9cbc40m63f2d3/T/form-init8893781347079502941.clj:1:1062) user=> (if (nil? (resolve 'foo)) #_=> (do (def foo 42) (prn "true-branch")) #_=> (prn "false-branch")) "false-branch" nil user=> foo #object[clojure.lang.Var$Unbound 0x6dc69f03 "Unbound: #'user/foo"] Seems once clojure interpreter declares the variable before really evaluate the clause with def. Is this an expected behavior? Should I ever use def in if or fn? Thanks! Kaiming -- 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/d/optout.
