Cannot use VAR more than once on the same variable (and declaring empty array)

[casson-projects-2020]

First let me say: great project! I was searching for a way to program macros in SVG editors for ever and PSVG solves this problem for me.

I have two things to point out: when I try to execute this example (found in your docs):

  <var data="M 0 0 L 10 10"/>
  <var data="CAT(data,'L',20,10)"/> <!-- adds a new point -->
  <path d="{data}">

Chrome (version 89.0.4389.90) raises an "Identifer data has already been declared" error.

I was able to circumvent the problem, but that end up being kinda ugly :) and is the source of the second point.

I declared the variable just once and then manipulate it using dummy attributes, using javascript inside them (what I believe can be against the philosophy of the language):

  <var incs="0 0 1 1 0 0" />
  <var ps="[ ]" />
  <g style="{ps.shift(),ps.shift()}"></g>
  <for i="0" true="{i<5}">
    <g style="{ps.push((px + w * incs[ i ]) * scale, (py + h * incs[ i + 1 ]) * scale )}"></g>
  </for>

My intention was to declare an empty array and the only way I could manage it was to declare ps="[ ]" (notice that this generates and array, with the 1st element == "[" and the second == "]" :) ) and then use "shift" twice in the next line.

So my second point is: Is there a way to declare empty arrays? I've tried ps="" and then use "push", ps="[]" (but that generates a string, I think), and

  <var ps="" /><g style="{ps=[]}"></g> 

and no one of them worked.

Also it appears to me (but I can be wrong, please point it out if it is the case) that the builtins CAT, NTH and etc cannot be used inside { } in PSVG, hence the use of "push".