effect-development

What it does and when to use it

Effect development guidance. Use when implementing or reviewing code that composes Effect APIs or patterns, or that adds or changes API signatures.

How it works

1. API conventions

---
name: effect-development
description: Effect development guidance. Use when implementing or reviewing code that composes Effect APIs or patterns, or that adds or changes API signatures.
---

Use the repository's AI documentation as targeted reference, not ambient
context:

1. Identify the Effect APIs and concepts involved in the change.
2. Search `LLMS.md` and `ai-docs/src` for those names and concepts, then read
   the matching sections and examples.
3. Apply the relevant guidance and inspect nearby source and tests for any
   repository-internal conventions not covered by the documentation.

The task is ready for implementation when every material Effect API or pattern
has matching local guidance, or the search has established that none exists.

## API conventions

Write option types inline in the signature by default. Mark fields `readonly`
and add `| undefined` to optional fields:

```ts
export const make = (options: {
  readonly capacity: number
  readonly strategy?: "dropping" | "sliding" | undefined
}): Effect.Effect<Queue> => ...
```

Declare a named options type only in these cases:

- A substantial set of options is shared across several APIs, so a named type
  keeps them in sync.
- The options type needs complex conditional logic, such as conditional or
  mapped types driven by type parameters.

A long option list for a single API is not on its own a reason to extract a
named type.

Versions

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Database snapshot: 13.11.2026 · package version 88a8fba613d0 (SHA-256 digest of the entire package)

Downloads in the last 30 days: 0 · ranking

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