filter

neuro.iterator.filter

Instance method on Iterator.prototype.

Creates an iterator whose values are those from this iterator for which the provided predicate returns true.

Signatures

filter(input: { iterator: <receiver>; predicate?: (value: T; index: number) => boolean; prompt?: string }): Promise<IteratorObject<S, undefined, unknown>>
filter(input: { iterator: <receiver>; predicate?: (value: T; index: number) => unknown; prompt?: string }): Promise<IteratorObject<T, undefined, unknown>>

The prompt field is optional. When omitted (or set to an empty string) the wrapper falls back to the native Iterator.prototype.filter and returns a resolved Promise without contacting the LLM. When present, the LLM is given the original arguments plus your prompt and is asked to behave like the original method.

Example

import { configureClient, neuro } from 'neuro-ts';

configureClient({ apiKey: process.env.OPENAI_API_KEY });

// Lazy filter; pairs with .take(n) for early-exit "first N matches" patterns.
await neuro.iterator.filter({ iterator: events, predicate: (e) => e.severity > 1, prompt: 'yield only the values where the predicate returns true, lazily -- the version of Array.prototype.filter that finally lets you express "first N matches in this stream" without buffering the rest' });

System prompt

The exact system prompt the SDK sends to your model when you provide a prompt field:

Generated promptIterator.prototype.filter

You are simulating the JavaScript built-in `Iterator.prototype.filter`.
## Original signature(s)
  Overload 1: (predicate?: (value: T, index: number) => boolean) => IteratorObject<S, undefined, unknown>
  Overload 2: (predicate?: (value: T, index: number) => unknown) => IteratorObject<T, undefined, unknown>
## JSDoc
Creates an iterator whose values are those from this iterator for which the provided predicate returns true.

## How to respond
- Behave EXACTLY as the original `filter` would, but use the user's intent to choose any callback / comparator / transform logic that the original would normally accept as an argument.
- Strictly preserve the original return type and shape.
- Output ONLY the JSON-encoded return value of the function call.
- Do NOT include explanations, prose, comments, or markdown fences.
- If the function would return `undefined`, output the literal string `undefined`.
- For Date / RegExp / Map / Set / TypedArray returns, output an object of the form { "__type": "Date" | "RegExp" | "Map" | "Set" | "<TypedArrayName>", ... } so the SDK can rehydrate it.