mod identities
{
    use std::ops::{Add};

    pub trait AdditiveIdentity<_AdditiveIdentity = Self> where
        Self: Sized + Add<_AdditiveIdentity, Output = Self>,
        _AdditiveIdentity: Sized + Add<Self, Output = Self>
    {
        const ADDITIVE_IDENTITY: _AdditiveIdentity;
    }

    impl AdditiveIdentity for i32
    {
        const ADDITIVE_IDENTITY: Self = 0;
    }

    impl AdditiveIdentity for f64
    {
        const ADDITIVE_IDENTITY: Self = 0.0;
    }
}

mod vector
{
    use crate::identities::{AdditiveIdentity};

    pub struct Vector<T>
    {
        pub components: T
    }

    impl<T> Vector<T> {
        pub /*const*/ fn additive_identity<U>() -> Vector<[U; 3]> where U: AdditiveIdentity
        {
            const ZERO_VECTOR: Vector<[U; 3]> = Vector{components: [ U::ADDITIVE_IDENTITY,  U::ADDITIVE_IDENTITY,  U::ADDITIVE_IDENTITY]};
            ZERO_VECTOR

            // let f1 = || { Vector{components: [ U::ADDITIVE_IDENTITY,  U::ADDITIVE_IDENTITY,  U::ADDITIVE_IDENTITY]} };
            // let f2 = || { const ZERO_VECTOR: Vector<[U; 3]> = f1(); ZERO_VECTOR };
            // f2()
        }
    }
}

fn main() {
    println!("Hello, world!");
}