This is actually a really good question. I found myself wondering the same
thing the other day.
On Monday, February 24, 2014 1:54:59 PM UTC+2, andrew cooke wrote:
>
> Working on the finite field code I found myself asking "what is a Number?".
>
> One answer is:
>
> julia> Base.subtypetree(Number)
> (Number,{(Complex{Float16},{}),(Complex{Float32},{}),(Complex{Float64
> },{}),(Complex{T<:Real},{}),(Real,{(FloatingPoint,{(BigFloat,{}),(Float16
> ,{}),(Float32,{}),(Float64,{})}),(Integer,{(BigInt,{}),(Bool,{}),(Char
> ,{}),(Signed,{(Int128,{}),(Int16,{}),(Int32,{}),(Int64,{}),(Int8,{})}),(
> Unsigned,{(Uint128,{}),(Uint16,{}),(Uint32,{}),(Uint64,{}),(Uint8
> ,{})})}),(MathConst{sym},{}),(Rational{T<:Integer},{})})})
>
> but that doesn't help so much. What I really wanted to know is - what
> methods are assumed to exist for something that is a subtype of Number?
>
> And I don't know how to answer that.
>
> Maybe (I don't think so) Julia needs some kind of concept like abstract
> methods, where you can name methods for Number that any subtype must
> implement?
>
> Maybe there needs to be some kind of tool that introspects the code base
> and says "90% of subtypes define real and abs"?
>
> Maybe this has already been discussed or is clearly not an issue?
>
> Andrew
>
