Implement Distribution for Range(Inclusive)

src/distributions/uniform.rs

@@ -290,6 +290,18 @@ impl<X: SampleUniform> From<::core::ops::RangeInclusive<X>> for Uniform<X> {
     }
 }
 
+impl<T: SampleUniform> Distribution<T> for ::core::ops::Range<T> {
+    fn sample<R: Rng + ?Sized>(&self, rng: &mut R) -> T {
+        T::Sampler::sample_single(&self.start, &self.end, rng)
+    }
+}
+
+impl<T: SampleUniform> Distribution<T> for ::core::ops::RangeInclusive<T> {
+    fn sample<R: Rng + ?Sized>(&self, rng: &mut R) -> T {
+        T::Sampler::sample_single_inclusive(self.start(), self.end(), rng)
+    }
+}
+
 /// Helper trait similar to [`Borrow`] but implemented
 /// only for SampleUniform and references to SampleUniform in
 /// order to resolve ambiguity issues.
@@ -1274,6 +1286,17 @@ mod tests {
         assert_eq!(r.inner.scale, 5.0);
     }
 
+    #[test]
+    fn test_std_range_distribution() {
+        let mut rng = crate::test::rng(474);
+        for _ in 0..100 {
+            let x = rng.sample(0..10);
+            assert!(x >= 0 && x < 10);
+            let x = rng.sample(0..=10);
+            assert!(x >= 0 && x <= 10);
+        }
+    }
+
     #[test]
     fn test_uniform_from_std_range_inclusive() {
         let r = Uniform::from(2u32..=6);

src/lib.rs

@@ -227,9 +227,10 @@ pub trait Rng: RngCore {
     /// use rand::distributions::Uniform;
     ///
     /// let mut rng = thread_rng();
-    /// let x = rng.sample(Uniform::new(10u32, 15));
+    /// let x = rng.sample(10u32..15);
     /// // Type annotation requires two types, the type and distribution; the
-    /// // distribution can be inferred.
+    /// // distribution can be inferred. `Uniform` is more efficient than the
+    /// // above range syntax if multiple samples are taken.
     /// let y = rng.sample::<u16, _>(Uniform::new(10, 15));
     /// ```
     fn sample<T, D: Distribution<T>>(&mut self, distr: D) -> T {