1 files changed, 139 insertions, 9 deletions

diff --git a/src/lib.rs b/src/lib.rs
index 1303f3d..a7146b8 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,14 +1,144 @@
-pub fn add(left: u64, right: u64) -> u64 {
-	left + right
+pub trait Tuple {
+	type AsRef<'a>: Tuple
+	where
+		Self: 'a;
+	type AsMut<'a>: Tuple
+	where
+		Self: 'a;
+
+	type Reversed: Tuple;
+
+	fn as_ref(&self) -> Self::AsRef<'_>;
+	fn as_mut(&mut self) -> Self::AsMut<'_>;
+	fn rev(self) -> Self::Reversed;
+}
+
+pub trait Tuple1: Tuple {
+	type Item0;
+	type Rest: Tuple;
+
+	fn into_0(self) -> Self::Item0;
+	fn split_into(self) -> (Self::Item0, Self::Rest);
+	fn into_rest(self) -> Self::Rest;
+}
+
+pub trait Tuple2: Tuple1 {
+	type Item1;
+	type Rest: Tuple;
+
+	fn into_1(self) -> Self::Item1;
+	fn into_rest(self) -> <Self as Tuple2>::Rest;
+}
+
+impl Tuple for () {
+	type AsRef<'a>
+		= ()
+	where
+		Self: 'a;
+	type AsMut<'a>
+		= ()
+	where
+		Self: 'a;
+
+	type Reversed = ();
+
+	fn as_ref(&self) -> Self::AsRef<'_> {}
+	fn as_mut(&mut self) -> Self::AsMut<'_> {}
+	fn rev(self) -> Self::Reversed {}
+}
+
+impl<A> Tuple for (A,) {
+	type AsRef<'a>
+		= (&'a A,)
+	where
+		Self: 'a;
+	type AsMut<'a>
+		= (&'a mut A,)
+	where
+		Self: 'a;
+
+	type Reversed = (A,);
+
+	fn as_ref(&self) -> Self::AsRef<'_> {
+		(&self.0,)
+	}
+
+	fn as_mut(&mut self) -> Self::AsMut<'_> {
+		(&mut self.0,)
+	}
+
+	fn rev(self) -> Self::Reversed {
+		(self.0,)
+	}
+}
+
+impl<A, B> Tuple for (A, B) {
+	type AsRef<'a>
+		= (&'a A, &'a B)
+	where
+		Self: 'a;
+	type AsMut<'a>
+		= (&'a mut A, &'a mut B)
+	where
+		Self: 'a;
+
+	type Reversed = (B, A);
+
+	fn as_ref(&self) -> Self::AsRef<'_> {
+		(&self.0, &self.1)
+	}
+
+	fn as_mut(&mut self) -> Self::AsMut<'_> {
+		(&mut self.0, &mut self.1)
+	}
+
+	fn rev(self) -> Self::Reversed {
+		(self.1, self.0)
+	}
+}
+
+impl<A> Tuple1 for (A,) {
+	type Item0 = A;
+	type Rest = ();
+
+	fn into_0(self) -> Self::Item0 {
+		self.0
+	}
+
+	fn split_into(self) -> (Self::Item0, <Self as Tuple1>::Rest) {
+		(self.0, ())
+	}
+
+	fn into_rest(self) -> Self::Rest {}
+}
+
+impl<A, B> Tuple1 for (A, B) {
+	type Item0 = A;
+
+	type Rest = (B,);
+
+	fn into_0(self) -> Self::Item0 {
+		self.0
+	}
+
+	fn split_into(self) -> (Self::Item0, <Self as Tuple1>::Rest) {
+		(self.0, (self.1,))
+	}
+
+	fn into_rest(self) -> Self::Rest {
+		(self.1,)
+	}
 }
 
-#[cfg(test)]
-mod tests {
-	use super::*;
+impl<R: Tuple1, T: Tuple1<Rest = R>> Tuple2 for T {
+	type Item1 = R::Item0;
+	type Rest = R::Rest;
+
+	fn into_1(self) -> Self::Item1 {
+		self.into_rest().into_0()
+	}
 
-	#[test]
-	fn it_works() {
-		let result = add(2, 2);
-		assert_eq!(result, 4);
+	fn into_rest(self) -> <Self as Tuple2>::Rest {
+		self.into_rest().into_rest()
 	}
 }