Add an impl of 'Zero' for 'NotNaN'

src/lib.rs

@@ -15,7 +15,7 @@ use std::fmt;
 use std::io;
 use std::mem;
 use unreachable::unreachable;
-use num_traits::Float;
+use num_traits::{Float, Zero};
 
 // masks for the parts of the IEEE 754 float
 const SIGN_MASK: u64 = 0x8000000000000000u64;
@@ -516,6 +516,16 @@ impl<T: Float> Neg for NotNaN<T> {
     }
 }
 
+impl<T: Float + Zero> Zero for NotNaN<T> {
+    fn zero() -> Self {
+        NotNaN(T::zero())
+    }
+
+    fn is_zero(&self) -> bool {
+        *self == Self::zero()
+    }
+}
+
 /// An error indicating an attempt to construct NotNaN from a NaN
 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
 pub struct FloatIsNaN;