use bad_optics::{lenses::*, prisms::*, traversals::*}; #[derive(Debug, PartialEq, Clone)] struct MyStruct { hey: (u8, (u8, [Option; 5])), } fn main() { // make a lens that accesses `hey` in `MyStruct` let hey = lens( |hello: MyStruct| hello.hey, |mut hello: MyStruct, v| { hello.hey = v; hello }, ); // the thing we want to access let thing: (MyStruct, &'static str) = ( MyStruct { hey: (1, (2, [None, Some(1), Some(2), None, Some(4)])), }, "hello", ); let array_lens = _0 // access the first element in the tuple + hey // access hey + _1 // access the second element in the tuple + _1; // access the second element in the tuple assert_eq!(array_lens(thing.clone()).len(), 5); let lens = array_lens + each // access each element of the [Option; 5] array + _Some; // access the ones that are Some; assert_eq!(lens(thing.clone()), vec![1, 2, 4]); assert_eq!( lens(thing, |v| v + 10), ( MyStruct { hey: (1, (2, [None, Some(11), Some(12), None, Some(14)])), }, "hello", ) ); }