2021-11-05 12:05:55 +00:00
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mod identity;
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pub use identity::id;
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2021-11-05 13:27:34 +00:00
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2021-11-05 11:03:17 +00:00
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mod first;
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pub use first::_0;
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2021-11-05 13:27:34 +00:00
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mod second;
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pub use second::_1;
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2021-11-05 15:55:49 +00:00
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use crate::{Optics, OpticsTrait};
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/// For lenses that allow viewing
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pub trait LensView<T>: OpticsTrait {
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type Field;
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fn view(thing: T) -> Self::Field;
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}
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/// For lenses that allow setting
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pub trait LensOver<T>: LensView<T> {
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fn over<F>(thing: T, f: F) -> T
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where
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F: FnOnce(Self::Field) -> Self::Field;
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fn set(thing: T, v: Self::Field) -> T {
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Self::over(thing, |_| v)
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}
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}
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impl<L, T> LensView<T> for Optics<L>
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where
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L: LensView<T>,
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{
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type Field = L::Field;
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fn view(thing: T) -> Self::Field {
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L::view(thing)
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}
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}
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impl<L, T> LensOver<T> for Optics<L>
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where
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L: LensOver<T>,
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{
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fn over<F>(thing: T, f: F) -> T
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where
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F: FnOnce(Self::Field) -> Self::Field,
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{
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L::over(thing, f)
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}
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}
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pub fn view<T, L: LensView<T>>(_lens: L, thing: T) -> L::Field {
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L::view(thing)
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}
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pub fn set<T, L: LensOver<T>>(_lens: L, thing: T, v: L::Field) -> T {
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L::set(thing, v)
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}
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pub fn over<T, L: LensOver<T>>(_lens: L, thing: T, f: impl FnOnce(L::Field) -> L::Field) -> T {
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L::over(thing, f)
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}
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2021-11-05 19:35:26 +00:00
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#[cfg(test)]
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mod tests {
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use super::*;
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#[test]
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fn view_first_from_tuple() {
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let a = (1, 2);
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assert_eq!(view(_0, a), 1);
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let a = (1, 2);
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assert_eq!(view(_0, &a), &1);
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let mut a = (1, 2);
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assert_eq!(view(_0, &mut a), &mut 1);
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let a = (1, 2, 3);
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assert_eq!(view(_0, a), 1);
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let a = (1, 2, 3);
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assert_eq!(view(_0, &a), &1);
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}
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#[test]
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fn view_first_from_tuple_mut_works() {
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let mut a = (1, 2);
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*view(_0, &mut a) += 1;
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assert_eq!(a, (2, 2));
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}
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#[test]
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fn set_first_from_tuple() {
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let a = (1, 2);
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let a = set(_0, a, 3);
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assert_eq!(a, (3, 2));
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}
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#[test]
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fn over_first_from_tuple() {
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let a = (1, 2);
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let a = over(_0, a, |v| v + 1);
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assert_eq!(a, (2, 2));
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}
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#[test]
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fn over_first_from_array() {
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let a = [1, 2, 3, 4];
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let a = over(_0, a, |v| v + 1);
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assert_eq!(a, [2, 2, 3, 4]);
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}
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#[test]
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fn second() {
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let a = (1, 2);
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let a = over(_1, a, |v| v + 1);
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assert_eq!(a, (1, 3));
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let a = [1, 2, 3, 4];
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let a = over(_1, a, |v| v + 1);
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assert_eq!(a, [1, 3, 3, 4]);
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}
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#[test]
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fn view_combination() {
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let a = ((1, 2), 3);
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let lens = _0 + _1;
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let a = view(lens, a);
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assert_eq!(a, 2);
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}
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#[test]
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fn over_combination() {
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let a = ((1, 2), 3);
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let lens = _0 + _1;
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let a = over(lens, a, |v| v + 1);
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assert_eq!(a, ((1, 3), 3));
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}
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#[test]
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fn call_as_funcs() {
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let a = (1, 2);
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assert_eq!(_0(a), 1);
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let a = (1, 2);
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assert_eq!(_0(a, |v| v + 1), (2, 2));
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let a = ((1, 2), 3);
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let res = _0(a);
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assert_eq!(res, (1, 2));
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let lens = _0 + _1;
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let res = lens(a);
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assert_eq!(res, 2);
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let res = lens(a, |v| v + 1);
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assert_eq!(res, ((1, 3), 3));
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}
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}
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