Re: [sage-devel] Re: On scientific computing, Python and Julia
> In my code I actually have
>
> myfun{T <: Ring}(a::Poly{T}, b::Poly{T})
>
> a lot. Is there a shorthand for this?
I don't think so. According to
https://github.com/JuliaLang/julia/issues/6984, it may be possible to
have the following in the future:
myfun{P<:Poly{<:Ring}}(a::P, b::P)
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Re: [sage-devel] Re: On scientific computing, Python and Julia
> or to constrain argument types, e.g.
> myfun{T}(a::Poly{T}, b::Poly{T}) = a+b # a and b must be Polys of the same
> type
which is better expressed as :
myfun{P<:Poly}(a::P, b::P) = a+b
So a better example:
myfun{T}(a::Poly{T}, b::Monomial{T}) = ...
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Re: [sage-devel] Re: On scientific computing, Python and Julia
> Sorry, I had some errors in this next bit.
>> myfun(a :: Union(EuclideanPoly, Poly))
> It should have been
> myfun{T <: Union(EuclideanPoly, Poly)}(a :: T)
The first version is perfectly ok and more idiomatic in this case. You
said earlier:
> So typically function signatures will look like
> fnname{T <: Z}(a :: T)
> where we have:
> a is a value
> T is a type
> Z is a typeclass
Function signatures typically look like this only when T (a type
variable) is used in the function definition, e.g.
myfun{T}(::Poly{T}) = T
or to constrain argument types, e.g.
myfun{T}(a::Poly{T}, b::Poly{T}) = a+b # a and b must be Polys of the same type
or to constrain the type variable, e.g.
myfun{T<:Field}(a::Poly{T}) = 1/coeff(a)[1] # method of myfun working
only with Polys over fields (and "myfun(a::Poly{<:Field})" is
envisioned)
Otherwise, "fname(a :: Z)" is the way, even if Z is abstract
(typeclass). And even then, the concrete type of "a" can be referred
to via "typeof(a)". And fname will be compiled separately for each
concrete type it is called on.
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