add _1, impl combinations

src/combinations.rs

@@ -0,0 +1,41 @@
+use crate::{Lens, LensOver, LensTrait, LensView};
+
+pub struct Combination<A, B>(A, B);
+impl<A, B> LensTrait for Combination<A, B> {}
+
+impl<A, B> std::ops::Add<Lens<B>> for Lens<A>
+where
+    A: LensTrait,
+    B: LensTrait,
+{
+    type Output = Lens<Combination<Lens<A>, Lens<B>>>;
+
+    fn add(self, rhs: Lens<B>) -> Self::Output {
+        Lens(Combination(self, rhs))
+    }
+}
+
+impl<A, B, T> LensView<T> for Combination<A, B>
+where
+    A: LensView<T>,
+    B: LensView<A::Field>,
+{
+    type Field = B::Field;
+
+    fn view(thing: T) -> Self::Field {
+        B::view(A::view(thing))
+    }
+}
+
+impl<A, B, T> LensOver<T> for Combination<A, B>
+where
+    A: LensOver<T>,
+    B: LensOver<A::Field>,
+{
+    fn over<F>(thing: T, f: F) -> T
+    where
+        F: FnOnce(Self::Field) -> Self::Field,
+    {
+        A::over(thing, |b| B::over(b, f))
+    }
+}

src/lenses/first.rs

@@ -1,17 +1,19 @@
-use crate::{LensOver, LensView};
+use crate::{Lens, LensOver, LensTrait, LensView};
 
-pub struct _0;
+pub struct _0Inner;
+pub const _0: Lens<_0Inner> = Lens(_0Inner);
+impl LensTrait for _0Inner {}
 
 macro_rules! make_tuples {
     ($f:ident, ( $( $v:ident ),* ), ( $( $t:ident ),* ) ) => {
-        impl< $($t,)* > LensView<( $($t,)* )> for _0 {
+      impl< $($t,)* > LensView<( $($t,)* )> for _0Inner {
             type Field = T;
 
             fn view(( $($v,)* ): ($($t,)*)) -> Self::Field {
                 $f
             }
         }
-        impl< $($t,)* > LensOver<( $($t,)* )> for _0 {
+      impl< $($t,)* > LensOver<( $($t,)* )> for _0Inner {
             fn over<F>(
                 mut tup: ($($t,)*),
                 f: F
@@ -24,14 +26,14 @@ macro_rules! make_tuples {
             }
         }
 
-        impl<'a, $($t,)* > LensView<&'a ( $($t,)* )> for _0 {
+      impl<'a, $($t,)* > LensView<&'a ( $($t,)* )> for _0Inner {
             type Field = &'a T;
 
             fn view(( $($v,)* ): &'a ($($t,)*)) -> Self::Field {
                 $f
             }
         }
-        impl<'a, $($t,)* > LensView<&'a mut ( $($t,)* )> for _0 {
+      impl<'a, $($t,)* > LensView<&'a mut ( $($t,)* )> for _0Inner {
             type Field = &'a mut T;
 
             fn view(( $($v,)* ): &'a mut ($($t,)*)) -> Self::Field {
@@ -51,14 +53,14 @@ make_tuples!(t, (t, _u, _v, _w, _x, _y, _z), (T, U, V, W, X, Y, Z));
 
 macro_rules! make_arrays {
     ($f:ident, $n:expr, [$( $v:ident ),*]) => {
-        impl<T> LensView<[T; $n]> for _0 {
+      impl<T> LensView<[T; $n]> for _0Inner {
             type Field = T;
 
             fn view([ $($v,)* ]: [T; $n]) -> Self::Field {
                 $f
             }
         }
-        impl<T> LensOver<[T; $n]> for _0 {
+      impl<T> LensOver<[T; $n]> for _0Inner {
             fn over<F>(
               tup: [T; $n],
               fun: F
@@ -72,14 +74,14 @@ macro_rules! make_arrays {
             }
         }
 
-        impl<'a, T> LensView<&'a [T; $n]> for _0 {
+      impl<'a, T> LensView<&'a [T; $n]> for _0Inner {
             type Field = &'a T;
 
             fn view([ $($v,)* ]: &'a [T; $n]) -> Self::Field {
                 $f
             }
         }
-        impl<'a, T> LensView<&'a mut [T; $n]> for _0 {
+      impl<'a, T> LensView<&'a mut [T; $n]> for _0Inner {
             type Field = &'a mut T;
 
             fn view([ $($v,)* ]: &'a mut [T; $n]) -> Self::Field {

src/lenses/identity.rs

@@ -1,16 +1,17 @@
-use crate::{LensOver, LensView};
+use crate::{LensOver, LensTrait, LensView};
 
 #[allow(non_camel_case_types)]
 pub struct id;
 
-impl<T> LensView<T> for T {
+impl LensTrait for id {}
+impl<T> LensView<T> for id {
     type Field = T;
 
     fn view(thing: T) -> Self::Field {
         thing
     }
 }
-impl<T> LensOver<T> for T {
+impl<T> LensOver<T> for id {
     fn over<F>(thing: T, f: F) -> T
     where
         F: FnOnce(Self::Field) -> Self::Field,

src/lenses/mod.rs

@@ -1,4 +1,7 @@
 mod identity;
 pub use identity::id;
+
 mod first;
 pub use first::_0;
+mod second;
+pub use second::_1;

src/lenses/second.rs

@@ -0,0 +1,99 @@
+use crate::{Lens, LensOver, LensTrait, LensView};
+
+pub struct _1Inner;
+pub const _1: Lens<_1Inner> = Lens(_1Inner);
+impl LensTrait for _1Inner {}
+
+macro_rules! make_tuples {
+    ($f:ident, ( $( $v:ident ),* ), ( $( $t:ident ),* ) ) => {
+      impl< $($t,)* > LensView<( $($t,)* )> for _1Inner {
+            type Field = T;
+
+            fn view(( $($v,)* ): ($($t,)*)) -> Self::Field {
+                $f
+            }
+        }
+      impl< $($t,)* > LensOver<( $($t,)* )> for _1Inner {
+            fn over<F>(
+                mut tup: ($($t,)*),
+                f: F
+            ) -> ( $($t,)* )
+            where
+              F: FnOnce(Self::Field) -> Self::Field
+            {
+                tup.1 = f(tup.1);
+                tup
+            }
+        }
+
+      impl<'a, $($t,)* > LensView<&'a ( $($t,)* )> for _1Inner {
+            type Field = &'a T;
+
+            fn view(( $($v,)* ): &'a ($($t,)*)) -> Self::Field {
+                $f
+            }
+        }
+      impl<'a, $($t,)* > LensView<&'a mut ( $($t,)* )> for _1Inner {
+            type Field = &'a mut T;
+
+            fn view(( $($v,)* ): &'a mut ($($t,)*)) -> Self::Field {
+                $f
+            }
+        }
+    };
+}
+
+make_tuples!(t, (_u, t), (U, T));
+make_tuples!(t, (_u, t, _v), (U, T, V));
+make_tuples!(t, (_u, t, _v, _w), (U, T, V, W));
+make_tuples!(t, (_u, t, _v, _w, _x), (U, T, V, W, X));
+make_tuples!(t, (_u, t, _v, _w, _x, _y), (U, T, V, W, X, Y));
+make_tuples!(t, (_u, t, _v, _w, _x, _y, _z), (U, T, V, W, X, Y, Z));
+// not doing more cause i'm lazy, open a pr if you need more :)
+
+macro_rules! make_arrays {
+    ($f:ident, $n:expr, [$( $v:ident ),*]) => {
+      impl<T> LensView<[T; $n]> for _1Inner {
+            type Field = T;
+
+            fn view([ $($v,)* ]: [T; $n]) -> Self::Field {
+                $f
+            }
+        }
+      impl<T> LensOver<[T; $n]> for _1Inner {
+            fn over<F>(
+              tup: [T; $n],
+              fun: F
+            ) -> [T; $n]
+            where
+              F: FnOnce(Self::Field) -> Self::Field
+            {
+              let [$($v,)*] = tup;
+              let $f = fun( $f );
+              [$($v,)*]
+            }
+        }
+
+      impl<'a, T> LensView<&'a [T; $n]> for _1Inner {
+            type Field = &'a T;
+
+            fn view([ $($v,)* ]: &'a [T; $n]) -> Self::Field {
+                $f
+            }
+        }
+      impl<'a, T> LensView<&'a mut [T; $n]> for _1Inner {
+            type Field = &'a mut T;
+
+            fn view([ $($v,)* ]: &'a mut [T; $n]) -> Self::Field {
+                $f
+            }
+        }
+    };
+}
+
+make_arrays!(t, 2, [_a, t]);
+make_arrays!(t, 3, [_a, t, _b]);
+make_arrays!(t, 4, [_a, t, _b, _c]);
+make_arrays!(t, 5, [_a, t, _b, _c, _d]);
+make_arrays!(t, 6, [_a, t, _b, _c, _d, _e]);
+make_arrays!(t, 7, [_a, t, _b, _c, _d, _e, _g]);

src/lib.rs

@@ -1,9 +1,14 @@
-pub trait LensView<T> {
+/// Base trait
+pub trait LensTrait {}
+
+/// For lenses that allow viewing
+pub trait LensView<T>: LensTrait {
     type Field;
 
     fn view(thing: T) -> Self::Field;
 }
 
+/// For lenses that allow setting
 pub trait LensOver<T>: LensView<T> {
     fn over<F>(thing: T, f: F) -> T
     where
@@ -14,6 +19,32 @@ pub trait LensOver<T>: LensView<T> {
     }
 }
 
+/// Wrapper type
+pub struct Lens<T: LensTrait>(T);
+
+impl<L: LensTrait> LensTrait for Lens<L> {}
+impl<L, T> LensView<T> for Lens<L>
+where
+    L: LensView<T>,
+{
+    type Field = L::Field;
+
+    fn view(thing: T) -> Self::Field {
+        L::view(thing)
+    }
+}
+impl<L, T> LensOver<T> for Lens<L>
+where
+    L: LensOver<T>,
+{
+    fn over<F>(thing: T, f: F) -> T
+    where
+        F: FnOnce(Self::Field) -> Self::Field,
+    {
+        L::over(thing, f)
+    }
+}
+
 pub fn view<T, L: LensView<T>>(_lens: L, thing: T) -> L::Field {
     L::view(thing)
 }
@@ -24,11 +55,11 @@ pub fn over<T, L: LensOver<T>>(_lens: L, thing: T, f: impl FnOnce(L::Field) -> L
     L::over(thing, f)
 }
 
-// TODO add Fn implementation for lenses
-//      with one param it should be view, with two it should be over
-// TODO add std::ops::Add to combine lenses
+mod combinations;
 
-// TODO add second_from_tuple, etc
+// TODO add fn impls
+
+// TODO add third_from_tuple, etc
 
 // TODO array traversals
 
@@ -38,17 +69,16 @@ pub mod lenses;
 
 #[cfg(test)]
 mod tests {
-    use super::{lenses::_0, *};
+    use super::{
+        lenses::{_0, _1},
+        *,
+    };
 
     #[test]
     fn view_first_from_tuple() {
         let a = (1, 2);
         assert_eq!(view(_0, a), 1);
 
-        // you can call it both ways
-        let a = (1, 2);
-        assert_eq!(_0::view(a), 1);
-
         let a = (1, 2);
         assert_eq!(view(_0, &a), &1);
 
@@ -75,10 +105,6 @@ mod tests {
         let a = (1, 2);
         let a = set(_0, a, 3);
         assert_eq!(a, (3, 2));
-
-        let a = (1, 2);
-        let a = _0::set(a, 3);
-        assert_eq!(a, (3, 2));
     }
 
     #[test]
@@ -86,17 +112,42 @@ mod tests {
         let a = (1, 2);
         let a = over(_0, a, |v| v + 1);
         assert_eq!(a, (2, 2));
-
-        let a = (1, 2);
-        let a = _0::over(a, |v| v + 1);
-        assert_eq!(a, (2, 2));
     }
 
     #[test]
     fn over_first_from_array() {
         let a = [1, 2, 3, 4];
 
-        let a = _0::over(a, |v| v + 1);
+        let a = over(_0, a, |v| v + 1);
         assert_eq!(a, [2, 2, 3, 4]);
     }
+
+    #[test]
+    fn second() {
+        let a = (1, 2);
+        let a = over(_1, a, |v| v + 1);
+        assert_eq!(a, (1, 3));
+
+        let a = [1, 2, 3, 4];
+        let a = over(_1, a, |v| v + 1);
+        assert_eq!(a, [1, 3, 3, 4]);
+    }
+
+    #[test]
+    fn view_combination() {
+        let a = ((1, 2), 3);
+
+        let lens = _0 + _1;
+        let a = view(lens, a);
+        assert_eq!(a, 2);
+    }
+
+    #[test]
+    fn over_combination() {
+        let a = ((1, 2), 3);
+
+        let lens = _0 + _1;
+        let a = over(lens, a, |v| v + 1);
+        assert_eq!(a, ((1, 3), 3));
+    }
 }