1 files changed, 6 insertions, 0 deletions
diff --git a/src/prelude/array.ts b/src/prelude/array.ts
index d02de9b2e5..560dfa080d 100644
--- a/src/prelude/array.ts
+++ b/src/prelude/array.ts
@@ -109,3 +109,9 @@ export function takeWhile<T>(f: Predicate<T>, xs: T[]): T[] {
 	}
 	return ys;
 }
+
+export function cumulativeSum(xs: number[]): number[] {
+	const ys = Array.from(xs); // deep copy
+	for (let i = 1; i < ys.length; i++) ys[i] += ys[i - 1];
+	return ys;
+}