sigma_types/
non_negative.rs

1//! Non-negative terms (defined by comparison to zero).
2
3use {
4    crate::{Sigma, Test, Zero},
5    core::{fmt, marker::PhantomData},
6};
7
8/// Non-negative terms (defined by comparison to zero).
9pub type NonNegative<Input> = Sigma<Input, NonNegativeInvariant<Input>>;
10
11/// Non-negative terms (defined by comparison to zero).
12#[derive(Clone, Copy, Debug, Default, Eq, Hash, Ord, PartialEq, PartialOrd)]
13pub struct NonNegativeInvariant<Input: fmt::Debug + PartialOrd + Zero>(PhantomData<Input>);
14
15impl<Input: fmt::Debug + PartialOrd + Zero> Test<Input, 1> for NonNegativeInvariant<Input> {
16    const ADJECTIVE: &str = "non-negative";
17    type Error<'i>
18        = NotNonNegative<'i, Input>
19    where
20        Input: 'i;
21
22    #[inline(always)]
23    fn test([input]: [&Input; 1]) -> Result<(), Self::Error<'_>> {
24        if *input >= Input::ZERO {
25            Ok(())
26        } else {
27            Err(NotNonNegative(input))
28        }
29    }
30}
31
32/// A term expected to be non-negative was, in fact, negative.
33#[derive(Clone, Copy, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)]
34pub struct NotNonNegative<'i, Input: fmt::Debug + PartialOrd + Zero>(&'i Input);
35
36impl<Input: fmt::Debug + PartialOrd + Zero> fmt::Display for NotNonNegative<'_, Input> {
37    #[inline]
38    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
39        #![expect(
40            clippy::use_debug,
41            reason = "Intentional and informative, not just forgotten print-debugging"
42        )]
43
44        let Self(z) = *self;
45        write!(f, "{z:#?} < {:#?}", Input::ZERO)
46    }
47}
sigma_types/non_negative.rs

sigma_types/
non_negative.rs
