Empty children and Clojure zippers -


why last expression retruns

{:a :foo, :args [{:id :xx}], :id :xx}

instead of:

{:a :foo, :args [], :id :xx}

(require '[clojure.zip :as zip])  (defn my-zipper [tree]   (zip/zipper     (fn branch? [node]       (:args node))     (fn children [node]       (:args node))     (fn make-node [node children]       (assoc node :args (vec children)))     tree))  (def z (my-zipper {:a :foo :args []}))  (loop [loc z]   (if (zip/end? loc)     (zip/node loc)     (recur       (zip/next           (zip/edit loc #(assoc % :id :xx))))))

it looks problem associated fact traversing zip/next reveals there 2 nodes :

(zip/node (zip/next z))             ;  => nil (zip/node (zip/next (zip/next z)))  ;  => {:a :foo :args []}

why that? there single node empty children there should 1 node, correct?

after looking @ code of clojure.zip/vector-zip conclude lack of node's children should communicated nil. empty sequence doesn't work. children function should be:

(fn children [node]       (seq (:args node)))

Comments

Post a Comment

Popular posts from this blog

PHP and MySQL WP -

i trying accomplish 2 things here code. writing php directly wp page using insert php plugin. 1) query mysql database , return results 1 column 4 columns. 2) make each result own hyperlink directs user new wp page runs new query on page. i able query show results , turn results dynamic hyperlink, cannot formatting down. right returns result 1 column. here have: [insert_php] $servername = "localhost"; $username = "login"; //edited privacy $password = "password"; //edited privacy $database = "database"; //edited privacy // create connection $conn = new mysqli($servername, $username, $password, $database); // check connection if ($conn->connect_error) { die("connection failed: " . $conn->connect_error); } echo "connected successfully"; //get results database $result = mysqli_query($conn,"select mine mines order mine"); $all_property = array(); //declare array saving property //showing proper...
Read more

android - InAppBilling registering BroadcastReceiver in AndroidManifest -

i'm implementing inapp billing in android app. works well, however, i'm trying decouple broadcast receiver activity manifest. suggestion in android's trivialdrive sample: // important: dynamically register broadcast messages updated purchases. // register receiver here instead of <receiver> in manifest // because call getpurchases() @ startup, therefore can ignore // broadcasts sent while app isn't running. // note: registering listener in activity bad idea, done here // because sample. regardless, receiver must registered after // iabhelper setup, before first call getpurchases(). currently there's class extends broadcastreceiver : public class iabbroadcastreceiver extends broadcastreceiver { /** * intent action receiver should filter for. */ public static final string action = "com.android.vending.billing.purchases_updated"; private final iabbroadcastlistener mlistener; public iabbroadcastreceiver(iabbroadcastlistener listener) { m...
Read more

go - golang pprof for c library code -

i have been trying profile golang application pprof, seems details of c code(linked static library) missed in output result. flame graph from frame graph can see c code time consuming reported within "runtime._externalcode", no details @ all. , sure static library compiled debug enable. so there way make pprof details(like stack trace) of 3rd party c code? or there other golang profiling tool this?
Read more