Trait frunk_core::hlist::LiftFrom

pub trait LiftFrom<T, I> {
    // Required method
    fn lift_from(part: T) -> Self;
}

Indexed type conversions of T -> Self with index I. This is a generalized version of From which for example allows the caller to use default values for parts of Self and thus “fill in the blanks”.

LiftFrom is the reciprocal of LiftInto.

use frunk::lift_from;
use frunk::prelude::*;

type H = HList![(), usize, f64, (), bool];

let x = H::lift_from(42.0);
assert_eq!(x, hlist![(), 0, 42.0, (), false]);

let x: H = lift_from(true);
assert_eq!(x, hlist![(), 0, 0.0, (), true]);

Required Methods

fn lift_from(part: T) -> Self

Performs the indexed conversion.

Implementors

impl<Head, Tail, ValAtIx, TailIx> LiftFrom<ValAtIx, There<TailIx>> for HCons<Head, Tail>where Head: Default, Tail: HList + LiftFrom<ValAtIx, TailIx>,

impl<Prefix, Suffix> LiftFrom<Prefix, Suffixed<Suffix>> for <Prefix as Add<Suffix>>::Outputwhere Prefix: HList + Add<Suffix>, Suffix: Default,

impl<T, Tail> LiftFrom<T, Here> for HCons<T, Tail>where Tail: Default + HList,