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Improve generics usability for `Array<T>`

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#264 7 comments 0 reactions 1 assignee View on GitHub

@9prady9 is already working on this.

Since Nov 28, 2020.

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This issue has not been assessed yet.

Description

Enhancement

I encountered difficulty when writing generic functions using Array<T> e.g.

fn test_basic_op<T>(a: &af::Array<T>)
where
    // T: af::Fromf64 + af::HasAfEnum + ???
{
    println!("Element-wise arithmetic");
    let b = af::add(&af::sin(a), &T::fromf64(1.5f64), false);

    let b2 = af::add(&af::sin(a), &af::cos(a), false);

    let b3 = !a;
    af::af_print!("sin(a) + 1.5 => ", b);
    af::af_print!("sin(a) + cos(a) => ", b2);
    af::af_print!("!a => ", b3);

    let a_plus_b = a.clone() + b.clone();
    af::af_print!("a + b", a_plus_b);

    let minus_a = -(a.clone());
    af::af_print!("-a ", minus_a);
}

After long fight with compile error, I found that

fn test_basic_op<T>(a: &af::Array<T>)
where
    T: af::HasAfEnum<UnaryOutType = T>
        + af::Fromf64
        + af::Convertable<OutType = T>
        + af::ImplicitPromote<T, Output = T>,
    af::Array<T>: std::ops::Neg<Output = af::Array<T>>,
{
    ...
}

compiles and it's OK.

However, I feel that:

  • Convertable and ImplicitPromote seems implementation detail and I don't want to write them every time when using Array<T>.
  • T should be Convertable<OutType=T> automatically when T: HasAfEnum (i.e. T is supported in arrayfire).

So I want:

  1. Alias-like trait (e.g. AfScalar: HasAfEnum + ...) which enables us ignoring implementation detail when using Array<T> in generic code
  2. Generic trait implementation (e.g. Convertable), not implementation for f32, f64 and other types individually

What are your thoughts?

Dominant language
Rust
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