Python yield syntax in Lua by abusing coroutines.

generators_in_lua.lua

function make_iter(f)
    return function(...)
        local args = ...
        local co = coroutine.create(f)
        return function()
            if coroutine.status(co) == "dead" then
                return nil
            end
            _, result = coroutine.resume(co, args)
            return result
        end
    end
end

local unique = make_iter(function(alist)
    local seen = {}
    for _, x in ipairs(alist) do
        if not seen[x] then
            yield(x)
            seen[x] = true
        end
    end
end)

for x in unique({1, 1, 2, 3, 2}) do
    print(x)
end

lua_example.lua

local unique = function(alist)
    local seen = {}
    return function(last)
        local last, x
        repeat
            last, x = next(alist, last)
        until x == nil or not seen[x]
        if x == nil then
            return nil
        else
            seen[x] = true
            return x
        end
    end
end

python_example.py

def unique(alist):
    seen = set()
    for x in alist:
        if x not in seen:
            yield x
            seen.add(x)

for x in unique([1, 1, 2, 3, 2]):
    print x

abusing?