Hi Alex, I ran into the same issue before and spent an embarrassing amount of time scratching my head before I realized that if
A <: B,
this does not imply that
Vector{A} <: Vector{B}.
It would be interesting to learn why this is the case because I would think it
should be.
To answer your question, try
f{T <: IntOrFloat}(x::Vector{T})
Hope this helps.
