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On 28 Jul 2006, at 13:24, Stefan Brantschen wrote:

Newbie question: I ran into the question how to use closures with recursion -- consider this snippet:

local function visited (x)
-- Check and register if a table 'x' has been visited
  local vis = {}
  return function (x)
  for _, v in pairs(vis) do
    if x == v then return true
  v[#v+1] = x
  return false

Other people have answered your closure problem I believe. I have a data structure improvement.

using vis as a characteristic table is way more efficient, simply associate "true" with each visited value:

if vis[x] then return true end
vis[x] = true
return false

I hope I'm not barking up the wrong tree here.