Crate num_lazy 

num-lazy helps you write numbers for generic-typed functions.

It is recommended to use num-lazy along with numeric-literals. Use num-lazy to access macros for constants and special values, while using numeric_literals for parsing floats or numeric literals.

use num_lazy::declare_nums;
use numeric_literals::replace_numeric_literals;
use num_traits::Float;

declare_nums!{@constant T}
declare_nums!{@special T}
// declare_nums!{@literal T} // Recommend using `numeric_literals` instead

// Or use this to declare all macros:
// declare_nums!{T}

#[replace_numeric_literals(T::from(literal).unwrap())]
fn circumference<T: Float>(radius: T) -> T {
    2 * pi!() * radius
}

See what numbers are declared in declare_nums.

If you declare_nums!() in the root of your crate, you don’t even need to import the macros to submodules. This will not re-export the macros to the public crate.

lib.rs or main.rs

use num_lazy::declare_nums;
declare_nums!{T}

// My submodules
pub mod generic_math;

generic_math.rs

pub fn circle_area<T: Float>(radius: T) -> T {
    pi!() * radius * radius
}

If you want to declare the numbers in the root of your crate but keep the macro contained in a module, you can simply:

lib.rs or main.rs

mod generics {
    use num_lazy::declare_nums;
    declare_nums!{T}
}

generic_math.rs

use crate::generics::*;

pub fn circle_area<T: Float>(radius: T) -> T {
    pi!() * radius * radius
}

Macros

declare_nums

Declare commonly used num generics.