creating-from-collections

description: Use fromIterable and fromArray to lift collections into Streams or Effects for batch or streaming processing. globs: "**/*.ts" alwaysApply: true

Creating from Collections

Rule: Use fromIterable and fromArray to lift collections into Streams or Effects for batch or streaming processing.

Example

import { Stream, Effect } from "effect";

// Stream: Create a stream from an array
const numbers = [1, 2, 3, 4];
const numberStream = Stream.fromIterable(numbers); // Stream<number>

// Stream: Create a stream from any iterable
function* gen() {
  yield "a";
  yield "b";
}
const letterStream = Stream.fromIterable(gen()); // Stream<string>

// Effect: Create an effect from an array of effects (batch)
const effects = [Effect.succeed(1), Effect.succeed(2)];
const batchEffect = Effect.all(effects); // Effect<[1, 2]>

Explanation:

• Stream.fromIterable creates a stream from any array or iterable, enabling streaming and batch operations.
• Effect.all (covered elsewhere) can be used to process arrays of effects in batch.

Explanation:
Lifting collections into Streams or Effects allows you to process data in a composable, resource-safe, and potentially concurrent way.
It also enables you to use all of Effect's combinators for transformation, filtering, and error handling.