Trait frunk::hlist::HFoldRightable

pub trait HFoldRightable<Folder, Init> {
    type Output;
    fn foldr(self, folder: Folder, i: Init) -> Self::Output;
}

Trait for performing a right fold over an HList

This trait is part of the implementation of the inherent method HCons::foldr. Please see that method for more information.

You only need to import this trait when working with generic HLists or Folders of unknown type. If the type of everything is known, then list.foldr(f, init) should "just work" even without the trait.

Associated Types

type Output

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Required methods

fn foldr(self, folder: Folder, i: Init) -> Self::Output

Perform a right fold over an HList.

Please see the inherent method for more information.

The only difference between that inherent method and this trait method is the location of the type parameters. (here, they are on the trait rather than the method)

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Implementors

impl<'a, F, R, H, Tail, Init> HFoldRightable<&'a F, Init> for HCons<H, Tail> where
    F: Fn(H, <Tail as HFoldRightable<&'a F, Init>>::Output) -> R,
    Tail: HFoldRightable<&'a F, Init>, 

type Output = R

fn foldr(
    self,
    folder: &'a F,
    init: Init
) -> <HCons<H, Tail> as HFoldRightable<&'a F, Init>>::Output

impl<F, FolderHeadR, FolderTail, H, Tail, Init> HFoldRightable<HCons<F, FolderTail>, Init> for HCons<H, Tail> where
    F: FnOnce(H, <Tail as HFoldRightable<FolderTail, Init>>::Output) -> FolderHeadR,
    Tail: HFoldRightable<FolderTail, Init>, 

type Output = FolderHeadR

fn foldr(
    self,
    folder: HCons<F, FolderTail>,
    init: Init
) -> <HCons<H, Tail> as HFoldRightable<HCons<F, FolderTail>, Init>>::Output

impl<F, Init> HFoldRightable<F, Init> for HNil

type Output = Init

fn foldr(self, F, i: Init) -> <HNil as HFoldRightable<F, Init>>::Output

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