Eval

local Stack Result in
    Stack={NewStack}
    Result={NewStack}
    for I in {Length L}..1;~1 do
        {Push Stack {Nth L I}}
    end
    for while:{Not {IsEmpty Stack}} do
        local Elt in
            Elt={Pop Stack}
            case Elt of
               '+' then {Push Result {Pop Result}+{Pop Result}}
            [] '*' then {Push Result {Pop Result}*{Pop Result}}
            [] '-' then {Push Result ~{Pop Result}+{Pop Result}}
            [] '/' then
                local X Y in
                    X={Pop Result}
                    Y={Pop Result}
                    {Push Result Y div X}
                end
            else {Push Result Elt} end
        end
    end
    {Pop Result}
end