@thi.ng/rstream/atom.d.ts

Reactive streams & subscription primitives for constructing dataflow graphs / pipelines

import type { Predicate2 } from "@thi.ng/api";
import type { ReadonlyAtom } from "@thi.ng/atom";
import type { CommonOpts } from "./api.js";
export interface FromAtomOpts<T> extends CommonOpts {
    /**
     * True, if the current atom value should be emitted when the stream
     * activates.
     *
     * @defaultValue true
     */
    emitFirst: boolean;
    /**
     * User predicate to determine value changes in atom. New values are
     * only emitted on stream if the predicate returns true.
     *
     * @defaultValue `!==`
     */
    changed: Predicate2<T>;
}
/**
 * Yields {@link Stream} of value changes in given [Atom-like state
 * container](https://thi.ng/atom).
 *
 * @remarks
 * [Attaches a
 * watch](https://docs.thi.ng/umbrella/api/interfaces/IWatch.html#addWatch) to
 * the atom and checks for value changes with given `changed` predicate (`!==`
 * by default). If the predicate returns truthy result, the new value is emitted
 * on the stream. If `emitFirst` is true (default), also emits atom's current
 * value when first subscriber attaches to stream.
 *
 * Also see {@link fromView}, {@link fromViewUnsafe}
 *
 * @example
 * ```ts tangle:../export/from-atom.ts
 * import { defAtom, defCursor } from "@thi.ng/atom";
 * import { fromAtom, trace } from "@thi.ng/rstream";
 *
 * type DB = { a: number; b?: number };
 *
 * const db = defAtom<DB>({ a: 23, b: 88 });
 * const cursor = defCursor(db, ["a"])
 *
 * fromAtom(cursor).subscribe(trace("cursor val:"))
 * // cursor val: 23
 *
 * cursor.reset(42);
 * // cursor val: 42
 *
 * db.reset({a: 66})
 * // cursor val: 66
 * ```
 *
 * @param atom -
 * @param opts -
 */
export declare const fromAtom: <T>(atom: ReadonlyAtom<T>, opts?: Partial<FromAtomOpts<T>>) => import("./stream.js").Stream<T>;
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