Remove Bot type in favour of Empty trait

src/convert.rs

@@ -26,79 +26,22 @@ pub const fn infallible_to_never(infallible: Infallible) -> ! {
     infallible_elim(infallible)
 }
 
-/// The bottom type ⊥ with no elements. Since it has no elements, having an element of `Bot` is an
-/// inherent contradiction and it can therefore be converted to any other type. In MLTT, this
-/// corresponds to a proof by contradiction.
-/// 
-/// `Bot` serves the same purpose as `std::convert::Infallible` and the currently unstable "never"
-/// type `!`, but provides more convenience methods than the former.
-pub struct Bot(BotRepr);
-
-impl Bot {
-    #[inline]
-    #[must_use]
-    pub const fn elim<T>(self) -> T {
-        self.0.elim()
-    }
+pub trait Empty: Sized {
+    fn elim<T>(self) -> T;
 
     #[inline]
-    #[must_use]
-    pub const fn elim_ref<T>(&self) -> T {
-        self.0.elim()
-    }
-
-    #[inline]
-    pub const fn never(self) -> ! {
+    fn never(self) -> ! {
         self.elim()
     }
 }
 
-impl Clone for Bot {
-    #[inline]
-    fn clone(&self) -> Self {
-        self.elim_ref()
-    }
-}
-
-impl Copy for Bot {}
-
-impl From<Infallible> for Bot {
-    #[inline]
-    fn from(infallible: Infallible) -> Self {
-        infallible_elim(infallible)
-    }
-}
-
-impl From<Bot> for Infallible {
+impl Empty for Infallible {
     #[inline]
-    fn from(bot: Bot) -> Self {
-        bot.elim()
+    fn elim<T>(self) -> T {
+        infallible_elim(self)
     }
 }
 
-enum BotRepr {}
-
-impl BotRepr {
-    #[inline]
-    const fn elim<T>(self) -> T {
-        match self {}
-    }
-
-    #[inline]
-    const fn elim_ref<T>(&self) -> T {
-        match *self {}
-    }
-}
-
-impl Clone for BotRepr {
-    #[inline]
-    fn clone(&self) -> Self {
-        self.elim_ref()
-    }
-}
-
-impl Copy for BotRepr {}
-
 #[inline]
 #[must_use]
 pub fn clone<T: Clone>(x: &T) -> T {

src/either.rs

@@ -1,7 +1,12 @@
-use std::{convert::identity, hint, ops::{Deref, DerefMut}};
+use std::{
+    convert::identity,
+    hint,
+    ops::{Deref, DerefMut}
+};
 
 use Either::{Inl, Inr};
-use crate::convert::{clone, clone_mut, copy, copy_mut};
+use crate::convert::{clone, clone_mut, copy, copy_mut, Empty};
+
 pub enum Either<L, R> {
     Inl(L),
     Inr(R),
@@ -174,6 +179,24 @@ impl<L, R> Either<L, R> {
         self.fold(Inr, Inl)
     }
 
+    #[inline]
+    #[must_use]
+    pub fn elim_l(self) -> R
+    where
+        L: Empty,
+    {
+        self.fold_l(<L as Empty>::elim)
+    }
+
+    #[inline]
+    #[must_use]
+    pub fn elim_r(self) -> L
+    where
+        R: Empty,
+    {
+        self.fold_r(<R as Empty>::elim)
+    }
+
     #[inline]
     #[must_use]
     pub fn some_l(self) -> Option<L> {
@@ -489,19 +512,17 @@ impl<T> Either<T, T> {
     }
 }
 
-impl<L, R> Clone for Either<L, R>
-where
-    L: Clone,
-    R: Clone,
-{
+impl<L: Empty, R: Empty> Empty for Either<L, R> {
+    fn elim<T>(self) -> T {
+        self.fold(<L as Empty>::elim, <R as Empty>::elim)
+    }
+}
+
+impl<L: Clone, R: Clone> Clone for Either<L, R> {
     #[inline]
     fn clone(&self) -> Self {
         self.as_ref().map(<L as Clone>::clone, <R as Clone>::clone)
     }
 }
 
-impl<L, R> Copy for Either<L, R>
-where
-    L: Copy,
-    R: Copy,
-{}
+impl<L: Copy, R: Copy> Copy for Either<L, R> {}