Add support for sampling from borrowed range

[uschi2000]

Background

In a simulation system, we repeatedly sample from immutable, non-empty ranges. I'd like to sample from a borrowed range like so:

let range = 0..10;
let sampled = (&range).sample_single(&mut rng).unwrap(); // does not compile
assert!(range.contains(&sampled));

Feature request

Add support for sampling from borrowed Range and RangeInclusive.

Proof of concept:

diff --git a/src/distr/uniform.rs b/src/distr/uniform.rs
index b59fdbf7..b16ae123 100644
--- a/src/distr/uniform.rs
+++ b/src/distr/uniform.rs
@@ -439,6 +439,18 @@ impl<T: SampleUniform + PartialOrd> SampleRange<T> for Range<T> {
     }
 }
 
+impl<T: SampleUniform + PartialOrd> SampleRange<T> for &Range<T> {
+    #[inline]
+    fn sample_single<R: RngCore + ?Sized>(self, rng: &mut R) -> Result<T, Error> {
+        T::Sampler::sample_single(&self.start, &self.end, rng)
+    }
+
+    #[inline]
+    fn is_empty(&self) -> bool {
+        !(self.start < self.end)
+    }
+}
+
 impl<T: SampleUniform + PartialOrd> SampleRange<T> for RangeInclusive<T> {
     #[inline]
     fn sample_single<R: RngCore + ?Sized>(self, rng: &mut R) -> Result<T, Error> {
@@ -451,6 +463,18 @@ impl<T: SampleUniform + PartialOrd> SampleRange<T> for RangeInclusive<T> {
     }
 }
 
+impl<T: SampleUniform + PartialOrd> SampleRange<T> for &RangeInclusive<T> {
+    #[inline]
+    fn sample_single<R: RngCore + ?Sized>(self, rng: &mut R) -> Result<T, Error> {
+        T::Sampler::sample_single_inclusive(self.start(), self.end(), rng)
+    }
+
+    #[inline]
+    fn is_empty(&self) -> bool {
+        !(self.start() <= self.end())
+    }
+}
+
 macro_rules! impl_sample_range_u {
     ($t:ty) => {
         impl SampleRange<$t> for RangeTo<$t> {
@@ -552,6 +576,19 @@ mod tests {
         }
     }
 
+    #[test]
+    fn can_sample_from_borrowed_range() {
+        let mut rng = crate::test::rng(804);
+
+        let range = 0..10;
+        let sampled = (&range).sample_single(&mut rng).unwrap();
+        assert!(range.contains(&sampled));
+
+        let range = 0..=10;
+        let sampled = (&range).sample_single(&mut rng).unwrap();
+        assert!(range.contains(&sampled));
+    }
+
     #[test]
     fn value_stability() {
         fn test_samples<T: SampleUniform + Copy + fmt::Debug + PartialEq>(

I'm happy to write the MR if you like the idea.