You can do something like this:
C:\Users\Ismael
λ julia5
_
_ _ _(_)_ | By greedy hackers for greedy hackers.
(_) | (_) (_) | Documentation: http://docs.julialang.org
_ _ _| |_ __ _ | Type "?help" for help.
| | | | | | |/ _' | |
| | |_| | | | (_| | | Version 0.5.0 (2016-09-19 18:14 UTC)
_/ |\__'_|_|_|\__'_| | Official http://julialang.org/ release
|__/ | x86_64-w64-mingw32
julia> Base.sum{T<:Real, S<:Real}(::Type{T}, xs::Range{S})::T = sum(xs)
julia> r = 1:100; sum(r), sum(Int32, r), sum(Rational{Int16}, r),
sum(Complex{BigInt}, r)
(5050,5050,5050//1,5050 + 0im)
julia> for T ∈ (Int32, Rational{Int16}, Complex{BigInt})
@assert sum(T, 1:100) |> typeof == T
end
julia>
El lunes, 17 de octubre de 2016, 8:19:51 (UTC-5), Ángel de Vicente escribió:
>
> Hi,
>
> probably a very basic question, but I'm just starting to play around
> with Julia types.
>
> I was hoping to improve the performance of a little program I wrote, so
> I decided to try Int32 integers instead of the default Int64, but if I
> try to use sum, it seems that it is expecting Int64 and the result is
> Int64, defeating the purpose of working with Int32 and actually making
> the code much slower than the naive version.
>
> ,----
> | julia> typeof(sum([i for i in Int32(1):Int32(100)]))
>
> |
> | Int64
> `----
>
> Do I have to write down my own Int32::sum function? I assume I'm missing
> something quite obvious?
>
> Thanks,
> --
> Ángel de Vicente
> http://www.iac.es/galeria/angelv/
>
