syntax sugary switch case in lua

switchcase.lua

local _nil = setmetatable({},{__newindex=function() end}) -- sentinel

local function switch(val)
        if val==nil then val=_nil end
        return function(cases)
                return (cases[val] or cases.default or function() end)()
        end
end

return setmetatable({["_nil"]=_nil,switch=switch},{__call=function(t,...) return switch(...) end})