1 files changed, 55 insertions, 0 deletions
diff --git a/src/data/composite/data/excludeFromList.js b/src/data/composite/data/excludeFromList.js
new file mode 100644
index 0000000..d798dcd
--- /dev/null
+++ b/src/data/composite/data/excludeFromList.js
@@ -0,0 +1,55 @@
+// Filters particular values out of a list. Note that this will always
+// completely skip over null, but can be used to filter out any other
+// primitive or object value.
+//
+// See also:
+//  - fillMissingListItems
+//
+// More list utilities:
+//  - withFilteredList, withMappedList, withSortedList
+//  - withFlattenedList, withUnflattenedList
+//  - withPropertyFromList, withPropertiesFromList
+//
+
+import {input, templateCompositeFrom} from '#composite';
+import {empty} from '#sugar';
+
+export default templateCompositeFrom({
+  annotation: `excludeFromList`,
+
+  inputs: {
+    list: input(),
+
+    item: input({defaultValue: null}),
+    items: input({type: 'array', defaultValue: null}),
+  },
+
+  outputs: ({
+    [input.staticDependency('list')]: list,
+  }) => [list ?? '#list'],
+
+  steps: () => [
+    {
+      dependencies: [
+        input.staticDependency('list'),
+        input('list'),
+        input('item'),
+        input('items'),
+      ],
+
+      compute: (continuation, {
+        [input.staticDependency('list')]: listName,
+        [input('list')]: listContents,
+        [input('item')]: excludeItem,
+        [input('items')]: excludeItems,
+      }) => continuation({
+        [listName ?? '#list']:
+          listContents.filter(item => {
+            if (excludeItem !== null && item === excludeItem) return false;
+            if (!empty(excludeItems) && excludeItems.includes(item)) return false;
+            return true;
+          }),
+      }),
+    },
+  ],
+});