Overview
deriving lens for custom data types.
see the guide
Example
Limitations
- can't derive
Lens
for enum. - can't derive
Prism
andReview
for the variant has more than one argument or has named field.
deriving lens for custom data types.
see the guide
#[derive(Debug, Optic, Lens)]
struct Baz<'a, A, B, C>{
#[optic(ref)]
a: &'a A, // can only take the immutable ref by optics::a
#[optic(mut)]
b: &'a mut B, // can take the mutable ref by optics::b
#[optic]
c: C // can mv it out by by optics::c
}
#[derive(Optic, Review, Prism, Debug)]
enum AnEnum<T> {
A(T, i32),
#[optic] B(T),
}
#[derive(Optic, Lens, Debug)]
struct Foo {
#[optic] a: i32,
#[optic] b: i32,
}
fn test() -> Option<()> {
let x = Review::review(optics!(Some.B), Foo {
a: 3,
b: 2,
});
assert_eq!(x.preview(optics!(Some.B.b))?, 2);
Some(())
}
Lens
for enum.Prism
and Review
for the variant has more than one argument or has named field.