Function fold_left

pub fn fold_left<'a, Brand, A, B>(
    f: ClonableFn<'a, B, ClonableFn<'a, A, B>>,
) -> ClonableFn<'a, B, ClonableFn<'a, Apply<Brand, (A,)>, B>>
where
    Brand: 'a + Kind<(A,)> + Foldable,
    A: 'a + Clone,
    B: 'a + Clone,
    Apply<Brand, (A,)>: 'a,

Folds the structure by applying a function from left to right.

Free function version that dispatches to the typeclass method.

The default implementation of fold_left is implemented in terms of fold_right, flip, compose and identity where:

((fold_left f) b) fa = (((fold_right (((compose (flip compose)) (flip f)))) identity) fa) b

Type Signature

forall f a b. Foldable f => (b -> a -> b) -> b -> f a -> b

Parameters

• f: A curried binary function that takes in the current value of the accumulator, the next item in the structure and returns the next value of accumulator.
• b: Initial value of type B.
• fa: A foldable structure containing values of type A.

Returns

Final value of type B obtained from the folding operation.

Examples

use fp_library::{brands::VecBrand, functions::fold_left};
use std::sync::Arc;

assert_eq!(
    fold_left::<VecBrand, _, _>(Arc::new(|carry| Arc::new(move |item| carry * 2 + item)))(0)(
        vec![1, 2, 3]
    ),
    11
);