Ah, got ya. Did not think of that :) Thanks for the insight!
Cheers, Leonardo Borges www.leonardoborges.com On Wed, Sep 14, 2011 at 11:29 PM, Chouser <chou...@gmail.com> wrote: > On Wed, Sep 14, 2011 at 8:58 AM, Leonardo Borges > <leonardoborges...@gmail.com> wrote: >> Hi Guys, >> I'm pretty new to clojure and to the list as well - this being my 1st >> message - so hello everyone :) >> I'm going through the book The Joy of Clojure which, pardon the pun, >> I'm enJOYing a lot and stumbled upon this function to find neighbors >> of a location in a 2D matrix: > > Glad you like the book [careful avoidance of pun intended]! > >> (defn neighbors >> ([size yx] (neighbors [[-1 0] [1 0] [0 -1] [0 1]] size yx)) >> ([deltas size yx] >> (filter (fn [new-yx] >> (every? #(< -1 % size) new-yx)) >> (map #(map + yx %) deltas)))) >> >> This syntax made me scratch my head since I believe it was the first >> time I saw it. However, upon closer analysis it seems it could be >> rewritten like this, yielding the same result: >> >> (defn neighbors-1 [size yx] >> (let [deltas [[-1 0] [1 0] [0 -1] [0 1]]] >> (filter (fn [new-yx] >> (every? #(< -1 % size) new-yx)) >> (map #(map + yx %) deltas)))) >> >> The second version feels a lot easier on my eyes. Am I missing >> something or they are really equivalent? And if so, why is the first >> syntax supported or better yet, when is it best to use it? > > The main difference is that the first version allows you to pass in > your own deltas. This could be useful if you wanted to include > diagonals as neighbors. We don't think we take advantage of the > flexibility anywhere in the book, so perhaps your version would indeed > be better. > > --Chouser > > -- > 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 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
