Reduced bundle size.

src/plugins/chart_expressions/expression_xy/common/expression_functions/reference_line_layer.ts

@@ -6,8 +6,7 @@
  * Side Public License, v 1.
  */
 
-import { validateAccessor } from '@kbn/visualizations-plugin/common/utils';
-import { LayerTypes, REFERENCE_LINE_LAYER, EXTENDED_Y_CONFIG } from '../constants';
+import { REFERENCE_LINE_LAYER, EXTENDED_Y_CONFIG } from '../constants';
 import { ReferenceLineLayerFn } from '../types';
 import { strings } from '../i18n';
 
@@ -41,16 +40,8 @@ export const referenceLineLayerFunction: ReferenceLineLayerFn = {
       help: strings.getLayerIdHelp(),
     },
   },
-  fn(input, args) {
-    const table = args.table ?? input;
-    const accessors = args.accessors ?? [];
-    accessors.forEach((accessor) => validateAccessor(accessor, table.columns));
-
-    return {
-      type: REFERENCE_LINE_LAYER,
-      ...args,
-      layerType: LayerTypes.REFERENCELINE,
-      table: args.table ?? input,
-    };
+  async fn(input, args, context) {
+    const { referenceLineLayerFn } = await import('./reference_line_layer_fn');
+    return await referenceLineLayerFn(input, args, context);
   },
 };

src/plugins/chart_expressions/expression_xy/common/expression_functions/reference_line_layer_fn.ts

@@ -0,0 +1,24 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License
+ * 2.0 and the Server Side Public License, v 1; you may not use this file except
+ * in compliance with, at your election, the Elastic License 2.0 or the Server
+ * Side Public License, v 1.
+ */
+
+import { validateAccessor } from '@kbn/visualizations-plugin/common/utils';
+import { LayerTypes, REFERENCE_LINE_LAYER } from '../constants';
+import { ReferenceLineLayerFn } from '../types';
+
+export const referenceLineLayerFn: ReferenceLineLayerFn['fn'] = async (input, args, handlers) => {
+  const table = args.table ?? input;
+  const accessors = args.accessors ?? [];
+  accessors.forEach((accessor) => validateAccessor(accessor, table.columns));
+
+  return {
+    type: REFERENCE_LINE_LAYER,
+    ...args,
+    layerType: LayerTypes.REFERENCELINE,
+    table: args.table ?? input,
+  };
+};

src/plugins/chart_expressions/expression_xy/common/types/expression_functions.ts

@@ -422,7 +422,7 @@ export type ReferenceLineLayerFn = ExpressionFunctionDefinition<
   typeof REFERENCE_LINE_LAYER,
   Datatable,
   ReferenceLineLayerArgs,
-  ReferenceLineLayerConfigResult
+  Promise<ReferenceLineLayerConfigResult>
 >;
 
 export type YConfigFn = ExpressionFunctionDefinition<typeof Y_CONFIG, null, YConfig, YConfigResult>;