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typewit::methods

Function zip4

Source 
pub const fn zip4<A, B, C, D>(
    wit0: A,
    wit1: B,
    wit2: C,
    wit3: D,
) -> Zip4Out<A, B, C, D>
where
    A: BaseTypeWitness + Zip4<B, C, D>,
    A::L: Sized,
    A::R: Sized,
    B: BaseTypeWitness,
    B::L: Sized,
    B::R: Sized,
    C: BaseTypeWitness,
    C::L: Sized,
    C::R: Sized,
    D: BaseTypeWitness,
Available on crate feature rust_1_65 only.
Expand description

Zips together four BaseTypeWitness types.

§Return type

The return type depends on the types of the arguments:

  • if all arguments are TypeEq, this returns a TypeEq
  • if any argument is a TypeNe, this returns a TypeNe
  • if any argument is a TypeCmp and no argument is a TypeNe, this returns a TypeCmp

§Example

§Basic

This example shows basic usage.

use typewit::{TypeCmp, TypeEq, TypeNe, type_eq, type_ne};
use typewit::methods::zip4;

with::<u8, u8, bool, u16, u32>(
    TypeEq::NEW,
    type_ne!(u8, bool),
    TypeCmp::Ne(type_ne!(u16, u32)),
);

const fn with<A, B, C, D, E>(eq: TypeEq<A, B>, ne: TypeNe<B, C>, cmp: TypeCmp<D, E>) {
    let _: TypeEq<(A, u64, B, i64), (B, u64, A, i64)> = 
        zip4(eq, type_eq(), eq.flip(), type_eq());

    let _: TypeNe<(A, E, B, B), (B, D, A, C)> = zip4(eq, cmp.flip(), eq.flip(), ne);

    let _: TypeCmp<(D, A, B, A), (E, B, A, B)> = zip4(cmp, eq, eq.flip(), eq);
}