Clourescript: converting array access

Question

Problem

I am trying to convert the following piece of code: https://github.com/mdn/webgl-examples/blob/gh-pages/tutorial/glUtils.js#L13-L15

The JavaScript code is:

Matrix.Translation = function (v)
{
  // ignore length 2 case for simplicty

  if (v.elements.length == 3) {
    var r = Matrix.I(4);
    r.elements[0][3] = v.elements[0];
    r.elements[1][3] = v.elements[1];
    r.elements[2][3] = v.elements[2];
    return r;
  }

  throw "Invalid length for Translation";
}

Now, I can rewrite it cljs as follows:

(defn translation [x y z]
  (let [r (. js/Matrix I 4)]
     r[0][3] = x ;; how do I write this?
     r[1][3] = y ;; how do I write this?
     r[2][3] = z ;; how do I write this?
  ))

Question

However, how do I write r[0][3] in cljs?

Piotrek Bzdyl · Accepted Answer · 2016-10-29 08:27:34Z

1

You can use aget and aset to work with Javascript arrays:

(def arr (array (array "a1" "a2") (array "b1" "b2") (array "c1" "c2")))

It creates following nested array:

#js [#js ["a1" "a2"] #js ["b1" "b2"] #js ["c1" "c2"]]

You can access nested elements with aget:

(aget arr 1 0)
;; => "b1"

And update with aset:

(aset arr 1 0 "newb1")

updates arr to:

#js [#js ["a1" "a2"] #js ["newb1" "b2"] #js ["c1" "c2"]]

You might want to take a look at other functions related to Javascript arrays: alength, array, make-array, array?.

answered Oct 29, 2016 at 8:27

Piotrek Bzdyl

13.2k1 gold badge36 silver badges51 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

Clourescript: converting array access

Problem

The JavaScript code is:

Now, I can rewrite it cljs as follows:

Question

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

Problem

The JavaScript code is:

Now, I can rewrite it cljs as follows:

Question

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related