ff: PrimeField::{is_even, is_odd}

ff/ff_derive/src/lib.rs

@@ -1029,6 +1029,11 @@ fn prime_field_impl(
                 r.0
             }
 
+            #[inline(always)]
+            fn is_odd(&self) -> bool {
+                self.into_repr().is_odd()
+            }
+
             fn char() -> #repr {
                 MODULUS
             }

ff/src/lib.rs

@@ -309,6 +309,15 @@ pub trait PrimeField: Field + From<u64> {
     /// the number is an element of the field.
     fn into_repr(&self) -> Self::Repr;
 
+    /// Returns true iff this element is odd.
+    fn is_odd(&self) -> bool;
+
+    /// Returns true iff this element is even.
+    #[inline(always)]
+    fn is_even(&self) -> bool {
+        !self.is_odd()
+    }
+
     /// Returns the field characteristic; the modulus.
     fn char() -> Self::Repr;