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+// Applies a map function to each item in a list, just like a normal JavaScript
+// map.
+//
+// Pass a filter (e.g. from withAvailabilityFilter) to process only items
+// kept by the filter. Other items will be left as-is.
+//
+// See also:
+//  - withFilteredList
+//  - withSortedList
+//
+
+import {input, templateCompositeFrom} from '#composite';
+import {stitchArrays} from '#sugar';
+
+export default templateCompositeFrom({
+  annotation: `withMappedList`,
+
+  inputs: {
+    list: input({type: 'array'}),
+    map: input({type: 'function'}),
+
+    filter: input({
+      type: 'array',
+      defaultValue: null,
+    }),
+  },
+
+  outputs: ['#mappedList'],
+
+  steps: () => [
+    {
+      dependencies: [input('list'), input('map'), input('filter')],
+      compute: (continuation, {
+        [input('list')]: list,
+        [input('map')]: mapFn,
+        [input('filter')]: filter,
+      }) => continuation({
+        ['#mappedList']:
+          stitchArrays({
+            item: list,
+            keep: filter ?? Array.from(list, () => true),
+          }).map(({item, keep}, index) =>
+              (keep
+                ? mapFn(item, index, list)
+                : item)),
+      }),
+    },
+  ],
+});