Re: minor lua refman grammar points

[David Manura <dm.lua@...>]

On Wed, Jan 19, 2011 at 10:29 PM, David Manura <dm.lua@math2.org> wrote:
> Two minor points about the grammar in the Lua Reference Manual:

Another trivial point:

  -- http://www.lua.org/manual/5.1/manual.html#2.4.5
    for var_1, ···, var_n in explist do block end
  is equivalent to the code:
     do
       local f, s, var = explist
       while true do
         local var_1, ···, var_n = f(s, var)
         var = var_1    --[*]
         if var == nil then break end   --[*]
         block
       end
     end

In actual implementations, there's no reason to set `var` on break, so
the marked [*] lines are swapped:

         if var_1 == nil then break end
         var = var_1