Comments on: On Lisp -> Clojure (Chapter 4)

By: Nevena

Nevena — Sat, 04 Dec 2010 00:09:10 +0000

flatten function won't work. clojure.core 1.2 has the right one.

By: fogus

fogus — Thu, 23 Jul 2009 18:36:42 +0000

@Kunjan,

One thing to be aware of with these posts -- they are hopelessly out of date. My use of lazy-cons is actually no longer legal Clojure code. At the time of this writing it was the way to cons an element onto the head of a sequence in a lazy way. By lazy I mean that the elements of the sequence are not calculated until accessed. Clojure is now mostly lazy and therefore it makes lazy-cons unnecessary. The more appropriate way to do this now is to use lazy-seq like so:

(def foo (cons (do (println "hi there") 'x) '()))  ;; you will see "hi there" printed... non-lazy
foo   ;;  you will see (x)

(def foo (lazy-seq (cons (do (println "fff") 'x) '())))  ;; nothing is printed, until...
foo
;; now you will see "hi there" printed during the lookup of foo

Hopefully, that clarifies matters.

-m

By: Kunjan

Kunjan — Thu, 23 Jul 2009 00:25:50 +0000

Hi, I am learning clojure. And your posts are very very helpful. Could you tell me why you use lazy to add to the list. I have seen a lot of lazy-cons and lazy-cat. What is the advantage of these?

Thanks.

By: David Siegel

David Siegel — Sun, 14 Dec 2008 09:06:56 +0000

Shouldn't (most) be:

(defn most [f xs] (let [x (reduce #(if (> (f %1) (f %2)) %1 %2) xs)] [x (f x)]))