Trait frunk_core::hlist::HZipFoldLeftable

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

Left fold for a given data structure

Associated Types

type Output

Required Methods

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

foldl over a data structure

let nil = HNil;

assert_eq!(nil.foldl(HNil, 0), 0);

let h = hlist![1, false, 42f32];

let folded = h.foldl(
    hlist![
        |acc, i| i + acc,
        |acc, b: bool| if !b && acc > 42 { 9000f32 } else { 0f32 },
        |acc, f| f + acc
    ],
    1
);

assert_eq!(42f32, folded)

Implementors

• impl<F, Acc> HZipFoldLeftable<F, Acc> for HNil
• impl<F, FolderHeadR, FolderTail, H, Tail, Acc> HZipFoldLeftable<HCons<F, FolderTail>, Acc> for HCons<H, Tail> where Tail: HZipFoldLeftable<FolderTail, FolderHeadR>,
        F: Fn(Acc, H) -> FolderHeadR