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On 2015-05-31, at 8:48 AM, Roberto Ierusalimschy <> wrote:
> A key point of '#' is this:
>  t[#t + 1] = v    -- add v to the end of the list
>  t[#t]            -- gives you the last element in the list
>  t[#t] = nil      -- removes the last element of the list
> Before proposting any other semantics for #, think whether it supports
> these basic list-manipulation operations (insertion, deletion, access
> to last), and whether it can *build* lists containing nils using those
> operations. If not, the new semantics is not solving the problem.

I am quoting this for two reasons:

1) This is a very concise and useful set of statements about #. I wish it could fit in the manual. I will settle for giving it Google juice in the archives.

2) Because these are fundamental operations, I would wish again for this delicious (and perhaps unhealthy) sugar:[#+1] = 7 ==>

  local _temp
  _temp =
  _temp[#_temp + 1] = 7

We had this in MOO, under the name t[$].