From 9aca91228a79cf9a22fc245b8deb1ba241cbf103 Mon Sep 17 00:00:00 2001
From: Karsten Schmidt <k@postspectacular.com>
Date: Tue, 26 Feb 2019 04:43:48 +0000
Subject: [PATCH] fix(transducers): update converge() & update readme

---
 packages/transducers/README.md             |  1 +
 packages/transducers/src/xform/converge.ts | 30 +++++++---------------
 2 files changed, 10 insertions(+), 21 deletions(-)

diff --git a/packages/transducers/README.md b/packages/transducers/README.md
index 190446be2b..d263ef31ce 100644
--- a/packages/transducers/README.md
+++ b/packages/transducers/README.md
@@ -642,6 +642,7 @@ tx.transduce(tx.map((x) => x*10), tx.push(), tx.range(4))
 
 - [benchmark](https://github.com/thi-ng/umbrella/tree/master/packages/transducers/src/xform/benchmark.ts)
 - [cat](https://github.com/thi-ng/umbrella/tree/master/packages/transducers/src/xform/cat.ts)
+- [converge](https://github.com/thi-ng/umbrella/tree/master/packages/transducers/src/xform/converge.ts)
 - [convolve2d](https://github.com/thi-ng/umbrella/tree/master/packages/transducers/src/xform/convolve.ts)
 - [dedupe](https://github.com/thi-ng/umbrella/tree/master/packages/transducers/src/xform/dedupe.ts)
 - [delayed](https://github.com/thi-ng/umbrella/tree/master/packages/transducers/src/xform/delayed.ts)
diff --git a/packages/transducers/src/xform/converge.ts b/packages/transducers/src/xform/converge.ts
index c21b4cba93..31d02debda 100644
--- a/packages/transducers/src/xform/converge.ts
+++ b/packages/transducers/src/xform/converge.ts
@@ -6,35 +6,24 @@ import { ensureReduced } from "../reduced";
 
 /**
  * Transducer which for each input `x` (apart from the very first one)
- * applies given predicate `pred` to previous input and `x` and only
- * passed values downstream as long as the predicate returns falsy
- * result. Once the result is truthy, transformation is terminated (by
- * emitting a `reduced()` value).
+ * applies given predicate `pred` to previous input and `x`. Only passes
+ * values downstream as long as the predicate returns a falsy result.
+ * Once the result is truthy, `x` is considered converged and the
+ * transformation is terminated (by emitting a `reduced()` value).
  *
  * This can be used to limit processing of inputs only as long as
  * there're noticeable changes (according to the predicate) and then
  * stop the transducer pipeline once results have converged.
  *
  * ```
- * // only take new values as long as difference to prev value is >= 0.1
+ * // process as long as difference to prev value is >= 0.01
  * [...converge(
  *       // predicate
- *       (a, b) => Math.abs(a - b) < 0.1,
+ *       (a, b) => Math.abs(a - b) < 0.01,
  *       // input sequence
- *       iterate((x, i) => x + 1 / i, 0)
+ *       iterate((x, i) => x + Math.pow(2, -i), 0)
  * )]
- *
- * // [ 0,
- * //   1,
- * //   1.5,
- * //   1.8333333333333333,
- * //   2.083333333333333,
- * //   2.283333333333333,
- * //   2.4499999999999997,
- * //   2.5928571428571425,
- * //   2.7178571428571425,
- * //   2.8289682539682537,
- * //   2.9289682539682538 ]
+ * // [ 0, 0.5, 0.75, 0.875, 0.9375, 0.96875, 0.984375, 0.9921875 ]
  * ```
  *
  * @see takeWhile
@@ -43,7 +32,6 @@ import { ensureReduced } from "../reduced";
  * @param src
  */
 export function converge<T>(pred?: Predicate2<T>): Transducer<T, T>;
-export function converge<T>(src: Iterable<T>): IterableIterator<T>;
 export function converge<T>(pred: Predicate2<T>, src: Iterable<T>): IterableIterator<T>;
 export function converge<T>(...args: any[]): any {
     return $iter(converge, args) ||
@@ -56,7 +44,7 @@ export function converge<T>(...args: any[]): any {
                 (acc, x: T) => {
                     if (done || (prev !== SEMAPHORE && pred(prev, x))) {
                         done = true;
-                        return ensureReduced(acc);
+                        return ensureReduced(r(acc, x));
                     }
                     prev = x;
                     return r(acc, x);