Type Definition tlist::IsEmpty

pub type IsEmpty<List> = <List as TList>::IsEmpty;

Available on crate feature typenum only.

Type-level ‘function’ returning typenum::B1 when the list is empty; typenum::B0 otherwise.

You can turn the result into a bool using IsEmpty<List>::BOOL or IsEmpty<List>::to_bool().

(See typenum::Bit for more on this.)

use tlist::*;
use typenum::{B0, B1, Bit};
use static_assertions::assert_type_eq_all as assert_type_eq;

assert_type_eq!(IsEmpty<TList![]>, B1);
assert_type_eq!(IsEmpty<TList![i32]>, B0);
assert_type_eq!(IsEmpty<TList![u32, i64]>, B0);

assert_eq!(IsEmpty::<TList![]>::BOOL, true);
assert_eq!(IsEmpty::<TList![&'static str]>::BOOL, false);

IsEmpty is a type-level function that works for any TList, returning a type-level boolean. If you want to constrain what kind of TList is allowed for a certain operation, use the Empty or NonEmpty constraining traits.