Add docs on how to write a function for both owned arrays and views

[dstansby]

I'm currently trying to write a function that can take either an owned array or a view. I'm currently relying on this stackoverflow post to do something like:

use ndarray::{ArrayBase, RawData, s, array, Ix1};

fn do_something_with_array<S>(a: &ArrayBase<S, Ix1>) where S: RawData{

}

fn main () {
    let a = array![1, 2, 3];
    do_something_with_array(&a);

    let slc = a.slice(s![1..3]);
    do_something_with_array(&slc);
}

I'm not sure if this is the best way though (certainly having to include a type parameter in the function definition seems clunky), so it would be good to get clarification and add a section to the docs explaining how to write these functions.

[nilgoyette]

I had to write several generic functions with ndarray and it was really unclear at first! I agree that we should add more documentation.

having to include a type parameter in the function definition seems clunky

There's no way to avoid the type parameter. In Rust, when you don't know the exact type, you must be generic over a trait. This is exactly what's going on here.