effect-facet-stream-runtime

name	effect-facet-stream-runtime
description	Guidance for facet `effect/Stream#runtime` focused on APIs like run, runSum, and runFold. Load after `effect-skill-router` when this facet is the primary owner.

Effect Facet Stream#runtime

Owned scope

• Owns only effect/Stream#runtime.
• Parent module: effect/Stream.

What it is for

• runCollect/runDrain/sink execution. Module-specific APIs and usage patterns for Effect programs.

API quick reference

• run
• runSum
• runFold
• runHead
• runLast
• fromPull
• runCount
• runDrain
• fromArray
• fromQueue
• fromArrays
• fromEffect
• fromPubSub
• runCollect
• runForEach
• fromChannel
• fromIterable
• fromSchedule
• Full API list: references/api-reference.md

How to use it

• Keep work focused on the runtime concern for effect/Stream.
• Start with constructor-style APIs to build values/services before composing operations.
• Treat stateful APIs as synchronization boundaries and keep updates atomic.
• Keep runtime/execute APIs at edges; compose pure transformations before execution.

Starter example

import { Console, Effect, Stream } from "effect";

const program = Effect.gen(function* () {
  yield* Stream.make(1, 2, 3).pipe(
    Stream.map((n) => n * 2),
    Stream.runForEach((n) => Console.log(n)),
  );
});

Effect.runPromise(program);
// Output:
// 2
// 4
// 6

Common pitfalls

• Concurrency helpers can hide ordering/cancellation behavior; test interruption and race paths.
• Prefer explicit, typed combinators over ad-hoc casting or unchecked assumptions.

Not covered here

• Sibling facets under the same parent are out of scope:
  • effect-facet-stream-combinators (effect/Stream#combinators)
  • effect-facet-stream-concurrency (effect/Stream#concurrency)
  • effect-facet-stream-constructors (effect/Stream#constructors)
  • effect-facet-stream-transforms (effect/Stream#transforms)
• Parent module ownership belongs to effect-module-stream.

Escalate to

• effect-module-stream for parent module-wide workflows.
• effect-skill-router for cross-module routing and ownership checks.

Reference anchors

• Parent tests: packages/effect/test/Stream.test.ts
• Parent tests: packages/effect/test/unstable/process/ChildProcess.test.ts
• API details: references/api-reference.md
• Usage notes: references/usage-reference.md
• Ownership mapping: references/owner.md