Trait Prism 

pub trait Prism<S, A>: HasGetter<S, A> + HasSetter<S, A> { }

A Prism is an optic that focuses on a potentially missing value, such as a variant of a sum type (enum).

It provides:

• try_get to optionally extract a focus value from a larger type
• set to set the focused value of a larger type

This is useful for working with enum variants, Option values, or other sum types where a focus value might be absent.

Type Arguments

• S: The data type the optic operates on
• A: The data type the optic focuses on

Note

This is a marker trait that is blanket implemented for all structs that satisfy the requirements.

See Also

• [Getter] — an optic that focuses on a potentially missing value in a larger type
• [Setter] — an optic that can change its focused value
• [Lens] — an optic that focuses on an always-present value in a product type (e.g., a required struct field)
• [FallibleIso] — a variant of Iso where the mapping might fail, returning an error
• [Iso] — an isomorphism optic representing a reversible bijective conversion between two types

Implementors

impl<S, A, P: HasGetter<S, A> + HasSetter<S, A>> Prism<S, A> for P