Added the Zero and One traits to sigils.

It looks like these may be removed from the standard library soon.

src/one.rs

@@ -0,0 +1,54 @@
+use std::ops::Mul;
+
+/// Defines a multiplicative identity element for `Self`.
+pub trait One: Sized + Mul<Self, Output=Self>
+{
+   /// Returns the multiplicative identity element of `Self`, `1`.
+   ///
+   /// # Laws
+   ///
+   /// ```{.text}
+   /// a * 1 = a       ∀ a ∈ Self
+   /// 1 * a = a       ∀ a ∈ Self
+   /// ```
+   ///
+   /// # Purity
+   ///
+   /// This function should return the same result at all times regardless of
+   /// external mutable state, for example values stored in TLS or in
+   /// `static mut`s.
+   fn one() -> Self;
+}
+
+
+
+macro_rules! one_impl
+{
+   ($varType: ty, $val: expr) =>
+   {
+      impl One for $varType
+      {
+         fn one() -> $varType
+         {
+            $val
+         }
+      }
+   }
+}
+
+
+
+one_impl!(u8, 1u8);
+one_impl!(u16, 1u16);
+one_impl!(u32, 1u32);
+one_impl!(u64, 1u64);
+one_impl!(usize, 1usize);
+
+one_impl!(i8, 1i8);
+one_impl!(i16, 1i16);
+one_impl!(i32, 1i32);
+one_impl!(i64, 1i64);
+one_impl!(isize, 1isize);
+
+one_impl!(f32, 1.0f32);
+one_impl!(f64, 1.0f64);