When I first looked at Clojure, I didn't get it (I scanned the docs for 10 - 15 minutes). A few month later, Stu Halloway said to give it a second look and boy am I glad I did. Go read Stu's book, or at least the first couple of chapters online at Manning. Digest for a bit. It'll be an eye opener.
On Fri, Oct 30, 2009 at 4:20 PM, David Nolen <dnolen.li...@gmail.com> wrote: > On Fri, Oct 30, 2009 at 4:42 PM, Chick Corea <chick.zco...@gmail.com> wrote: >> >> Is everything in Clojure immutable? For example, w/ this code-snippet >> >> (let [x nil] >> ;; do something and modify 'x' >> ) >> >> how does one modify the value of 'x' ? >> >> (let [x nil] (def x true)) >> >> this doesn't work. the "def' interns and defines a (dynamic) root- >> binding >> for 'x' which is accessible outside the lexical closure. > > Welcome to functional programming :) Yes defs like that are generally looked > down upon because all defs are top-level anyway. > >> >> So I want to ask, am I in the minority in thinking that read-only >> local bindings limit >> the programmer a lot. The only alternative that I see (w/ my limited >> imagination) >> is to create a "let" scope at the exact place that one needs it. But, >> IMO, that >> sucks - sorry for the vernacular; but it is wildly inconvenient for me >> for many reasons. > > That's the whole point of FP, referential transparency. With assignment you > lose that. Clojure provides a great number of tools for dealing with FP > style programming. If you really need mutability use a reference type- atom, > ref. > (def x (atom 0)) > (reset! x 1) > @x -> 1 > >> >> Do both of these statements intern a symbol? Or does the 2nd set the >> currently >> interned symbol to a new value ? >> >> (def x 1) >> (def x 2) > > I believe this means: > define a new var with the symbol 'x, bind it to the value 1. > bind that var to the value 2. > While it takes some time to get your head around the effect on programming > style, you'll be pleasantly surprised when you decide to add concurrency > into your program. Even if you don't, I think you'll find your programs > generally easier to debug. > > > > -- Howard M. Lewis Ship Creator of Apache Tapestry The source for Tapestry training, mentoring and support. Contact me to learn how I can get you up and productive in Tapestry fast! (971) 678-5210 http://howardlewisship.com --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
