"integer addition... operands are promoted to Int or UInt from narrower integer types" (http://docs.julialang.org/en/latest/manual/integers-and-floating-point-numbers/)
"These catch-all rules first promote all operands to a common type " ( http://docs.julialang.org/en/latest/manual/conversion-and-promotion/#man-conversion-and-promotion ) `Int8` is definitely not a subclass of `Int`, do this two assertions contradict to each other?
