closures capture lexical scope, binding creates dynamic scope. lexical scope is where a closure is defined, dynamic is when it is called.
because filter is lazy, the closure is called outside the dynamic scope created by binding On Jul 14, 1:07 pm, Aaron Cohen <remled...@gmail.com> wrote: > I'm a little unclear on why this happens still. > #(= % a) is a closure, correct? My understanding is that this should > capture the environment when it is defined. Why does "the environment" not > include the current bindings? > > -- Aaron > > On Tue, Jul 14, 2009 at 4:03 PM, Mark Engelberg > <mark.engelb...@gmail.com>wrote: > > > > > > > On Tue, Jul 14, 2009 at 12:40 PM, Jarkko Oranen<chous...@gmail.com> wrote: > > > This is a common gotcha. It's actually a laziness issue: the seq > > > produced by filter is realised only after it exits the binding scope, > > > thus producing '(1). You need to use "doall" to force the seq if you > > > want the binding to apply. > > > Yeah, but more and more I'm finding that with complex code, it can be > > rather difficult to identify the parts that are lazy and the parts > > that aren't. Which makes using binding rather risky. I've started to > > refactor most of my code to avoid dynamic binding, because I'm tired > > of getting burned by this gotcha. Which is a shame. --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
