diff -r 1a38447a89fa -r 9226980e45a7 src/collection.rs
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/collection.rs	Tue Dec 31 08:30:02 2024 -0500
@@ -0,0 +1,54 @@
+/*!
+Abstract collections of objects.
+*/
+
+use crate::loc::Loc;
+
+/// An abstract collection of elements.
+pub trait Collection : IntoIterator<Item = Self::Element> {
+    /// Type of elements of the collection
+    type Element;
+    /// Iterator over references to elements of the collection
+    type RefsIter<'a> : Iterator<Item=&'a Self::Element> where Self : 'a;
+
+    /// Returns an iterator over references to elements of the collection.
+    fn iter_refs(&self) -> Self::RefsIter<'_>;
+}
+
+/// An abstract collection of mutable elements.
+pub trait CollectionMut : Collection {
+    /// Iterator over references to elements of the collection
+    type RefsIterMut<'a> : Iterator<Item=&'a mut Self::Element> where Self : 'a;
+
+    /// Returns an iterator over references to elements of the collection.
+    fn iter_refs_mut(&mut self) -> Self::RefsIterMut<'_>;
+}
+
+/// Helps implement Collection and CollectionMut for slice-like collections.
+#[macro_export]
+macro_rules! slice_like_collection {
+    ($type : ty where $($where:tt)*) => {
+        impl<$($where)*> Collection for $type {
+            type Element = E;
+            type RefsIter<'_a> = std::slice::Iter<'_a, E> where Self : '_a;
+
+            #[inline]
+            fn iter_refs(&self) -> Self::RefsIter<'_> {
+                self.iter()
+            }
+        }
+
+        impl<$($where)*> CollectionMut for $type {
+            type RefsIterMut<'_a> = std::slice::IterMut<'_a, E> where Self : '_a;
+
+            #[inline]
+            fn iter_refs_mut(&mut self) -> Self::RefsIterMut<'_> {
+                self.iter_mut()
+            }
+        }
+    }
+}
+
+slice_like_collection!(Vec<E> where E);
+slice_like_collection!([E; N] where E, const N : usize);
+slice_like_collection!(Loc<E, N> where E, const N : usize);