feat: heterogeneous-list with reverse!

.gitignore

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+/target

Cargo.lock

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+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 4
+
+[[package]]
+name = "heterogeneous-list"
+version = "0.1.0"

Cargo.toml

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+[package]
+name = "heterogeneous-list"
+version = "0.1.0"
+edition = "2024"
+
+[dependencies]

src/hlist.rs

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+use hidden::HList_;
+
+mod hidden {
+    pub trait HList_ {}
+}
+
+pub trait Reversed<Cont>
+{
+    type Output: HList_;
+    fn reversed_prepend(self, cont: Cont) -> Self::Output;
+}
+
+impl<Cont> Reversed<Cont> for Nil
+    where Cont: HList_
+{
+    type Output = Cont;
+
+    fn reversed_prepend(self, cont: Cont) -> Self::Output {
+        cont
+    }
+}
+
+impl<Cont, Item, Rest> Reversed<Cont> for Cons<Item, Rest>
+    where 
+        Cont: HList_,
+        Rest: HList_ + Reversed<Cons<Item, Cont>>,
+        Self: HList_,
+        Cons<Item, Cont>: HList_
+{
+    type Output = <Rest as Reversed<Cons<Item, Cont>>>::Output;
+
+    fn reversed_prepend(self, cont: Cont) -> Self::Output {
+        self.1.reversed_prepend(Cons(self.0, cont))
+    }
+
+}
+
+pub trait HList
+    where 
+        Self: Sized + HList_ + Reversed<Nil> {
+    fn prepend<T>(self, value: T) -> Cons<T, Self> {
+        Cons(value, self)
+    }
+
+    type Reversed;
+    fn reversed(self) -> Self::Reversed;
+}
+impl HList for Nil {
+
+    type Reversed = Self::Output;
+
+    fn reversed(self) -> Nil{
+        Nil
+    }
+}
+impl<Item, Rest> HList for Cons<Item, Rest> 
+    where 
+        Rest: HList_,
+        Self: Reversed<Nil>
+{
+    type Reversed = Self::Output;
+    fn reversed(self) -> Self::Output {
+        self.reversed_prepend(Nil)
+    }
+}
+
+#[derive(Debug, Default, Clone, Copy, PartialEq, PartialOrd, Ord, Eq, Hash)]
+pub struct Cons<Item, Rest: HList_>(pub Item, pub Rest);
+impl<Item, Rest> HList_ for Cons<Item , Rest> 
+    where Rest: HList_ {}
+impl<Item, Rest: HList_> Cons<Item, Rest> {
+    pub fn uncons(self) -> (Item, Rest) {
+        (self.0, self.1)
+    }
+
+    pub fn head(&self) -> &Item {
+        &self.0
+    }
+}
+
+#[derive(Debug, Default, Clone, Copy)]
+pub struct Nil;
+impl HList_ for Nil {}

src/main.rs

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+use crate::hlist::HList;
+use hlist::Nil;
+
+pub mod hlist;
+
+fn main() {
+    let x = Nil
+.prepend(0)
+.prepend(1)
+.prepend(2)
+.prepend(3)
+.prepend(4)
+.prepend(5)
+.prepend(6)
+.prepend(7)
+.prepend(8)
+.prepend(9)
+.prepend(10)
+.prepend(11)
+.prepend(12)
+.prepend(13)
+.prepend(14)
+.prepend(15)
+.prepend(16)
+.prepend(17)
+.prepend(18)
+.prepend(19)
+.prepend(20)
+.prepend(21)
+.prepend(22)
+.prepend(23)
+.prepend(24)
+.prepend(25);
+    println!("{x:#?}");
+    let y = x.reversed();
+    println!("{y:#?}");
+}
+