13 unstable releases (3 breaking)
0.3.2 | May 7, 2021 |
---|---|
0.3.1 | Apr 8, 2021 |
0.2.2 | Apr 3, 2021 |
0.2.1 | Mar 29, 2021 |
0.0.88 | Mar 21, 2021 |
#4 in #traversing
Used in 3 crates
(via lens-rs)
105KB
2.5K
SLoC
Overview
deriving lens for custom data types.
see the guide
Example
#[derive(Debug, 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(Review, Prism, Debug)]
enum AnEnum<T> {
A(T, i32), // couldn't derive Prism or Review
#[optic]
B(T),
#[optic]
C,
#[optic]
D(),
#[optic]
E {},
}
#[derive(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(())
}
Limitations
- can't derive
Lens
for enum. - can't derive
Prism
andReview
for the variant has more than one argument or has named field.
Dependencies
~1.2–1.8MB
~42K SLoC