bad-optics/examples/struct_fields.rs

28 lines
598 B
Rust

use bad_optics::lenses::*;
#[derive(Debug, PartialEq, Clone)]
struct MyStruct {
hey: (u8, (u8, i32)),
}
fn main() {
// make a lens for Hello
let hey = lens(
|hello: MyStruct| hello.hey,
|mut hello: MyStruct, v| {
hello.hey = v;
hello
},
);
let my_struct = MyStruct { hey: (1, (2, -3)) };
// the thing we want to access
let thing = (my_struct, "hello");
// a lens that targets the -3 inside my_struct
let lens_that_targets_the_i32 = _0 + hey + _1 + _1;
assert_eq!(lens_that_targets_the_i32(thing), -3);
}