Expand description
This crate provides type-level numbers evaluated at compile time. It depends only on libcore.
The traits defined or used in this crate are used in a typical manner. They can be divided into two categories: marker traits and type operators.
Many of the marker traits have functions defined, but they all do essentially the same thing: convert a type into its runtime counterpart, and are really just there for debugging. For example,
use typenum::{Integer, N4};
assert_eq!(N4::to_i32(), -4);Type operators are traits that behave as functions at the type level. These are the meat of this library. Where possible, traits defined in libcore have been used, but their attached functions have not been implemented.
For example, the Add trait is implemented for both unsigned and signed integers, but the
add function is not. As there are never any objects of the types defined here, it wouldn’t
make sense to implement it. What is important is its associated type Output, which is where
the addition happens.
use std::ops::Add;
use typenum::{Integer, P3, P4};
type X = <P3 as Add<P4>>::Output;
assert_eq!(<X as Integer>::to_i32(), 7);In addition, helper aliases are defined for type operators. For example, the above snippet could be replaced with
use typenum::{Integer, Sum, P3, P4};
type X = Sum<P3, P4>;
assert_eq!(<X as Integer>::to_i32(), 7);Documented in each module is the full list of type operators implemented.
Re-exports
pub use crate::array::ATerm;pub use crate::array::TArr;pub use crate::int::NInt;pub use crate::int::PInt;pub use crate::uint::UInt;pub use crate::uint::UTerm;pub use crate::bit::B0;pub use crate::bit::B1;pub use crate::int::Z0;pub use crate::marker_traits::*;pub use crate::operator_aliases::*;pub use crate::type_operators::*;Modules
op! macro instead.core::ops.Macros
True, aka B1.op! instead.Structs
Cmp, this is the type equivalent to the enum variant
core::cmp::Ordering::Equal.Cmp, this is the type equivalent to the enum variant
core::cmp::Ordering::Greater.Cmp, this is the type equivalent to the enum variant
core::cmp::Ordering::Less.