add README.md

README.md

@@ -0,0 +1,24 @@
+# iter_accumulate
+An iterator adaptor for Rust that accumulates the elements from the base iterator
+using the provided closure.
+
+This is similar to `fold()`, but instead of returning the final accumulated result, it returns an
+iterator that yields the current accumulated value for each iteration. In other words, the last
+element yielded by `accumulate()` is what would have been returned by `fold()` if it was used
+instead.
+
+## Example
+
+```rust
+use iter_accumulate::IterAccumulate;
+
+let input = [1, 2, 3, 4, 5];
+let mut iter = input.iter().accumulate(1, |acc, i| acc * i);
+
+assert_eq!(iter.next(), Some(1));
+assert_eq!(iter.next(), Some(2));
+assert_eq!(iter.next(), Some(6));
+assert_eq!(iter.next(), Some(24));
+assert_eq!(iter.next(), Some(120));
+assert_eq!(iter.next(), None);
+```