diff --git a/README.md b/README.md
index 08b8ce7..29b773f 100644
--- a/README.md
+++ b/README.md
@@ -21,6 +21,7 @@ solution that could be applied to other functions as well, without too much over
 | `catAttrs`       | O(n)                | `filter`-like, [attrs] -> Attrs. Can remove many items at once, as well as convert from list to attrs |
 | `concatMap`      | O(n * f)            | could this be used with attr lookups to fix the O(n^2) fold collection resizing problem? |
 | `concatLists`    | O(n)                | could this be used with attr lookups to fix the O(n^2) fold collection resizing problem? |
+| `foldl'`         | O(n * f)            | could be used to implement tail recursion |
 | `filter`         | O(n * f)            | could potentially remove many items at once without realloc? |
 | `genList`        | O(n * f)            | can seemingly allocate an arbitrarily sized list? |
 | `intersectAttrs` | O(n log m) (known)  | could be used as a shorthand for binary merge? |