[julia-users] Re: Why does adding type assertion to field slow down this example?

[Jason Merrill]

On Thursday, June 9, 2016 at 6:36:35 PM UTC-4, Arch Robison wrote
>
> Yes, I know if I declare x with a concrete type such as Int, the code will 
> do blazingly fast.  But I was poking around to see if declaring it with an 
> abstract type narrower than Any would help.
>

I think the other piece of standard advice in situations like these is to 
make a parametric type instead of a single type with abstract fields, so

type NotAsSlow{T<:Unsigned}
  x::T
end


for i=1:3
    @time flog(NotAsSlow(UInt64(42)))
end

0.014765 seconds (8.38 k allocations: 342.502 KB)
0.000945 seconds (6 allocations: 192 bytes)
0.001423 seconds (6 allocations: 192 bytes)