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Programming-Idioms

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Idiom #118 List to set

Create the set y from the list x.
x may contain duplicates. y is unordered and has no repeated values.

Turning the list [a,b,c,b] into the set {c,a,b}
local hash = {}
local y = {}
for _,v in ipairs(x) do
   if (not hash[v]) then
       y[#y+1] = v
       hash[v] = true
   end
end
(def y (set x))

New implementation...
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