effect-module-channel

name	effect-module-channel
description	Guidance for `effect/Channel` focused on APIs like map, fail, and empty. Load after `effect-skill-router` when this module is the primary owner.

Effect Module Channel

Owned scope

• Owns only effect/Channel.
• Source of truth: packages/effect/src/Channel.ts.

What it is for

• The Channel module provides a powerful abstraction for bi-directional communication and streaming operations. A Channel is a nexus of I/O operations that supports both reading and writing, forming the foundation for Effect's Stream and Sink abstractions.

API quick reference

• map
• fail
• empty
• filter
• flatMap
• mapDone
• provide
• runDone
• runFold
• runHead
• runLast
• succeed
• failSync
• fromPull
• mapAccum
• mapError
• mapInput
• runCount
• Full API list: references/api-reference.md

How to use it

• Start with constructor-style APIs to build values/services before composing operations.
• Prefer pipe-based composition to keep transformations explicit and testable.
• Keep runtime/execute APIs at edges; compose pure transformations before execution.

Starter example

import { Channel } from "effect";

// Simple channel that outputs numbers
const numberChannel = Channel.succeed(42);

// Transform channel that doubles values
const doubleChannel = Channel.map(numberChannel, (n) => n * 2);

// Running the channel would output: 84

Common pitfalls

• Scoped resources require deterministic lifecycle management to avoid leaks.
• Concurrency helpers can hide ordering/cancellation behavior; test interruption and race paths.

Not covered here

• Deep module subsets are owned by these facet skills:
  • effect-facet-channel-composition (effect/Channel#composition)
  • effect-facet-channel-core (effect/Channel#core)
  • effect-facet-channel-utilities (effect/Channel#utilities)

Escalate to

• effect-skill-router for routing and ownership checks.
• First facet entrypoint: effect-facet-channel-composition.

Reference anchors

• Module source: packages/effect/src/Channel.ts
• Representative tests: packages/effect/test/Channel.test.ts
• API details: references/api-reference.md
• Usage notes: references/usage-reference.md
• Ownership mapping: references/owner.md