From eec483093df7075cc94f686b1440f0dcfd76f466 Mon Sep 17 00:00:00 2001
From: EuAndreh <eu@euandre.org>
Date: Fri, 11 Jul 2025 18:37:47 -0300
Subject: src/sjs.mjs: Add reductions()

---
 src/sjs.mjs | 29 ++++++++++++++++++++++++++---
 1 file changed, 26 insertions(+), 3 deletions(-)

(limited to 'src')

diff --git a/src/sjs.mjs b/src/sjs.mjs
index 2c9d551..e9da7fc 100644
--- a/src/sjs.mjs
+++ b/src/sjs.mjs
@@ -294,9 +294,8 @@ export const reduced = x => new Reduced(x);
 
 const reduceRec = (coll, fn, acc, index) =>
 	isReduced(acc) ? acc.value :
-		index === coll.length
-			? acc
-			: reduceRec(
+		index === coll.length ? acc :
+			reduceRec(
 				coll,
 				fn,
 				fn(acc, coll[index], index, coll),
@@ -308,6 +307,30 @@ export const reduce = (coll, fn, init) =>
 		? reduceRec(coll.slice(1), fn, coll[0], 0)
 		: reduceRec(coll,          fn, init,    0);
 
+const reductionsRec = (coll, fn, acc, index, steps) => {
+	if (isReduced(acc)) {
+		return steps.concat(acc.value);
+	}
+
+	if (index === coll.length) {
+		return steps;
+	}
+
+	const newAcc = fn(acc, coll[index], index, coll);
+	return reductionsRec(
+		coll,
+		fn,
+		newAcc,
+		index + 1,
+		steps.concat(newAcc),
+	);
+};
+
+export const reductions = (coll, fn, init) =>
+	init === undefined
+		? reductionsRec(coll.slice(1), fn, coll[0], 0, [coll[0]])
+		: reductionsRec(coll,          fn, init,    0, []);
+
 export const mapValues = (obj, fn) =>
 	Object.keys(obj).reduce(
 		(o, k) => ({
-- 
cgit v1.2.3