Trait RefTraversable

Source

pub trait RefTraversable:
    RefFunctor
    + RefFoldable
    + Kind_cdc7cd43dac7585f {
    // Required method
    fn ref_traverse<'a, FnBrand, A: 'a + Clone, B: 'a + Clone, F: Applicative>(
        func: impl Fn(&A) -> <F as Kind_cdc7cd43dac7585f>::Of<'a, B> + 'a,
        ta: &<Self as Kind_cdc7cd43dac7585f>::Of<'a, A>,
    ) -> <F as Kind_cdc7cd43dac7585f>::Of<'a, <Self as Kind_cdc7cd43dac7585f>::Of<'a, B>>
       where FnBrand: LiftFn + 'a,
             <Self as Kind_cdc7cd43dac7585f>::Of<'a, B>: Clone,
             <F as Kind_cdc7cd43dac7585f>::Of<'a, B>: Clone;
}

Expand description

By-reference traversal of structures.

Similar to Traversable, but the closure receives &A instead of A. This enables traversing collections by reference without consuming elements, or traversing memoized types that only provide &A access.

ref_traverse is the required method.

Required Methods§

Source

fn ref_traverse<'a, FnBrand, A: 'a + Clone, B: 'a + Clone, F: Applicative>( func: impl Fn(&A) -> <F as Kind_cdc7cd43dac7585f>::Of<'a, B> + 'a, ta: &<Self as Kind_cdc7cd43dac7585f>::Of<'a, A>, ) -> <F as Kind_cdc7cd43dac7585f>::Of<'a, <Self as Kind_cdc7cd43dac7585f>::Of<'a, B>>
where FnBrand: LiftFn + 'a, <Self as Kind_cdc7cd43dac7585f>::Of<'a, B>: Clone, <F as Kind_cdc7cd43dac7585f>::Of<'a, B>: Clone,

Maps each element by reference to a computation, evaluates them, and combines the results.

§Type Signature

forall A B F. (Applicative F, LiftFn FnBrand) => (&A -> F B, &Self A) -> F (Self B)

§Type Parameters

'a: The lifetime of the elements.
FnBrand: The brand of the cloneable function wrapper.
A: The type of the elements in the input structure.
B: The type of the elements in the output structure.
F: The applicative functor brand for the computation.

§Parameters

func: The function to apply to each element reference.
ta: The structure to traverse.

§Returns

The combined result in the applicative context.

§Examples

use fp_library::{
	brands::*,
	functions::*,
};

let v = vec![1, 2, 3];
let result: Option<Vec<String>> =
	ref_traverse::<VecBrand, RcFnBrand, _, _, OptionBrand>(|x: &i32| Some(x.to_string()), &v);
assert_eq!(result, Some(vec!["1".to_string(), "2".to_string(), "3".to_string()]));