# non-zero
A macro for creating constant non-zero integers (with type inference).
There are multiple crates that address the issue of initialising non-zero integers.
However, most of them lack type inference.
This is why I created `non_zero!`.
It uses `const` blocks to evaluate the literals at compile time whilst achieving type inference.
The definition is essentially this:
```rust
macro_rules! non_zero {
($n:expr) => {
const {
NonZero::new($n).unwrap()
}
};
}
```
Some things of note:
- `$n:expr` allows for any expression to be passed to the macro, so long as it is evaluable in a `const` context.
- The `const` block is discussed above.
- `NonZero` is the `std` generic non-zero type to which all `NonZero***` are aliased.
The generic argument can be inferred, not only from `$n` but also from the macro's usage.
- `.unwrap()` inside the `const` block will cause a compile-time error, not a runtime one.
The above implementation is somewhat simplified;
the real definition produces prettier errors than `unwrap` and is more hygienic.
## Naming
This crate uses the same name as `std` does for its types.
Namely, with a hyphen between "non" and "zero".
In `snake_case` the hyphen becomes an underscore and in `PascalCase` it creates a word break.
## License
Licensed under either of
* Apache License, Version 2.0
([LICENSE-APACHE](LICENSE-APACHE) or <http://www.apache.org/licenses/LICENSE-2.0>)
* MIT license
([LICENSE-MIT](LICENSE-MIT) or <http://opensource.org/licenses/MIT>)
at your option.
## Contribution
Unless you explicitly state otherwise, any contribution intentionally submitted
for inclusion in the work by you, as defined in the Apache-2.0 license, shall be
dual licensed as above, without any additional terms or conditions.