docs: Update history/explainer with resolution of #19

HISTORY.md

@@ -6,9 +6,19 @@ Presented to [plenary meeting as an update on 2021-10-26][2021-10-26].
 
 # 2021-12
 Presented to [plenary meeting for Stage 2 on 2021-12-14][2021-12-14].
-Was rejected due to need to clarify awaiting semantics
+Was rejected due to need to clarify `await`ing semantics
 with and without mapping-function arguments.
 
+# 2022-07
+Discussion occurred about `await`ing semantics and mapping functions in [issue
+#19][]. It was eventually decided to match `for await` and the proposed
+[AsyncIterator.prototype.toArray][iterator-helpers] by `await`ing values from
+input sync iterators once, `await`ing values from input async iterators not at
+all, and `await`ing results returned by mapping functions once.
+
 [2021-08-31]: https://github.com/tc39/notes/blob/HEAD/meetings/2021-08/aug-31.md
 [2021-10-26]: https://github.com/tc39/notes/blob/HEAD/meetings/2021-10/oct-26.md#arrayfromasync-update
 [2021-12-14]: https://github.com/tc39/notes/blob/HEAD/meetings/2021-12/dec-14.md#arrayfromasync-for-stage-2
+[issue #19]: https://github.com/tc39/proposal-array-from-async/issues/19
+[iterator-helpers]: https://github.com/tc39/proposal-iterator-helpers
+[iterator-helpers#168]: https://github.com/tc39/proposal-iterator-helpers/issues/168

README.md

@@ -402,11 +402,24 @@ Array.fromAsync([], 1);
 The [iterator-helpers][] proposal has toArray, which works with both sync and
 async iterables.
 
+[iterator-helpers]: https://github.com/tc39/proposal-iterator-helpers
+
 ```js
-Array.from(gen())
-gen().toArray()
-Array.fromAsync(asyncGen())
-asyncGen().toArray()
+// Array.from
+
+Array.from(input)
+Iterator(input).toArray()
+
+Array.from(input, mapfn)
+Iterator(input).map(mapfn).toArray()
+
+// Array.asyncFrom
+
+Array.fromAsync(input)
+AsyncIterator(input).toArray()
+
+Array.fromAsync(input, mapfn)
+AsyncIterator(input).map(mapfn).toArray()
 ```
 
 toArray overlaps with both Array.from and Array.fromAsync. This is okay. They
@@ -422,7 +435,6 @@ something one element at a time is the same as building it [more than one]
 element at a time, but sometimes it could be slow to build that way or produce
 a structure with equivalent semantics but different performance properties.”
 
-[iterator-helpers]: https://github.com/tc39/proposal-iterator-helpers
 [tc39/proposal-iterator-helpers#156]: https://github.com/tc39/proposal-iterator-helpers/issues/156.
 
 ### TypedArray.fromAsync, Set.fromAsync, Object.fromEntriesAsync, etc.