Trait frunk::hlist::LiftFrom

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

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::*;
use frunk_core::{HList, hlist};

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.

Object Safety§

This trait is not object safe.



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>>::Output
where Prefix: HList + Add<Suffix>, Suffix: Default,


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