The question of how vars work comes up enough that I recently wrote a blog post on the subject. Maybe it will be useful to you. http://blog.cognitect.com/blog/2016/9/15/works-on-my-machine-understanding-var-bindings-and-roots
Timothy On Fri, Dec 2, 2016 at 2:44 PM Paul Gowder <paul.gow...@gmail.com> wrote: > Thanks Bobby, Francis, Walter! Now trying to wrap my head around the idea > of def as a ref... > > On Friday, December 2, 2016 at 2:57:13 PM UTC-6, Francis Avila wrote: > > Let bindings are immutable bindings, not refs. They must act as if their > value could be substituted at the moment they are referenced. Def (i.e. a > ref) is a mutable container whose contents is examined when it is used (not > when referenced), which is why your second example works. > > > Why doesn't let work how you expect? Well, how would the following code > work if let worked as you intend? > > (let [a 1 > a (+ a 2)] > (= a 3)) > > However, fn accepts an optional name binding, so you can do this: > > (let [fib (fn fib [...] (fib ...))] fib) > > The inner fib reference is bound by the fn form, but the outer fib > reference is still bound by let. > > Or you can use letfn instead of let, which is the same as above with less > typing AND the bindings can all see one another simultaneously. It's best > for groups of closed-over but mutually recursive functions. > > (letfn [(fib [...] (fib ...))] (fib ...)) > > -- > 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. > -- 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.
