[wip] im tired boss

pkg/shared/kefir.ts

@@ -1,12 +1,18 @@
 import { merge, Observable } from "kefir";
 
-export const transform = <
-	T,
-	Mutations extends [Observable<any, any>, (prev: T, evt: any) => T][]
->(
-	initValue: T,
-	...mutations: Mutations
-): Observable<T, unknown> =>
+export type ValueWithin<O extends Observable<any, any>> = Parameters<
+	Parameters<O["map"]>[0]
+>[0];
+
+type Mutation<A, O extends Observable<any, any>> = [
+	O,
+	(prev: A, value: ValueWithin<O>) => A
+];
+
+export const multiScan = <A, M extends Mutation<A, any>[]>(
+	initValue: A,
+	...mutations: M
+): Observable<A, any> =>
 	merge(
 		mutations.map(([source, mutation]) =>
 			source.map((event) => ({ event, mutation }))
@@ -27,3 +33,5 @@ export const partition =
 			])
 		);
 	};
+
+export const isEmpty = (container: { length: number }) => container.length == 0;