pub fn fold_map<'a, FnBrand, Brand: Kind_cdc7cd43dac7585f, A: 'a, M: Monoid + 'a, FA, Marker>(
func: impl FoldMapDispatch<'a, FnBrand, Brand, A, M, FA, Marker>,
fa: FA,
) -> MExpand description
Maps values to a monoid and combines them.
Dispatches to Foldable::fold_map or RefFoldable::ref_fold_map
based on whether the closure takes A or &A.
The Marker and FA type parameters are inferred automatically by the
compiler from the closure’s argument type and the container argument.
§Type Signature
forall Brand A M. (Foldable Brand, Monoid M) => (A -> M, Brand A) -> M
§Type Parameters
'a: The lifetime of the values.FnBrand: The brand of the cloneable function to use.Brand: The brand of the foldable structure.A: The type of the elements.M: The monoid type.FA: The container type (owned or borrowed), inferred from the argument.Marker: Dispatch marker type, inferred automatically.
§Parameters
func: The mapping function.fa: The structure to fold (owned for Val, borrowed for Ref).
§Returns
The combined monoid value.
§Examples
use fp_library::{
brands::*,
functions::explicit::*,
types::*,
};
// By-value
let result = fold_map::<RcFnBrand, VecBrand, _, _, _, _>(|a: i32| a.to_string(), vec![1, 2, 3]);
assert_eq!(result, "123");
// By-ref
let lazy = RcLazy::new(|| 10);
let result =
fold_map::<RcFnBrand, LazyBrand<RcLazyConfig>, _, _, _, _>(|a: &i32| a.to_string(), &lazy);
assert_eq!(result, "10");