local M = {}

--- Capture `fn`'s upvalues and pass to `delegate`
---@param delegate fun(env: table<string, any>, _: ...): ...
---@param fn function
---@return fun(...): ...
function M.new(delegate, fn)
    local upvalues = {}
    for i = 1, debug.getinfo(fn, "u").nups do
        local name, value = debug.getupvalue(fn, i)
        upvalues[name] = value
    end
    return function(...)
        return delegate(upvalues, ...)
    end
end

return setmetatable(M, {
    __call = function(_, ...)
        return M.new(...)
    end,
})