// Idiomatic Effect-TS patterns for the marimo-lsp extension. Use when writing or reviewing Effect code in `extension/src` — grounded in this repo's actual usage and citing into vendored Effect source at `repos/effect/`.
| name | effect-ts |
| description | Idiomatic Effect-TS patterns for the marimo-lsp extension. Use when writing or reviewing Effect code in `extension/src` — grounded in this repo's actual usage and citing into vendored Effect source at `repos/effect/`. |
This skill is an index. Each file in patterns/ is a short, code-heavy reference for one slice of the Effect API, with worked examples from extension/src and cites into repos/effect/packages/effect/src/.
Run just vendor-effect first if repos/effect/ is empty — the pattern files reference paths inside it.
| Working on | Read |
|---|---|
A new service or wiring MainLive | patterns/layers-services.md |
A function in the Effect channel (entry point, span, log) | patterns/effect-core.md |
| Parsing data at a boundary (LSP, config, file) | patterns/schema.md |
Typed domain errors / catchTag / Cause / Exit | patterns/data-errors.md |
Consuming or producing a Stream (e.g. marimo/operation) | patterns/streams.md |
Replacing a nullable type or Either flow | patterns/option-either.md |
Holding state inside a service (Ref, SubscriptionRef, Deferred) | patterns/state.md |
Writing a test (it.effect, TestClock, mocks) | patterns/testing.md |
Every pattern file follows the same shape: TL;DR, constructors/combinators table, worked examples from this repo, worked examples from Effect itself, error handling, and a "what to avoid" section. Code samples honor the repo conventions in CLAUDE.md (named Effect.fn, annotateLogs over interpolation, withSpan on external calls, no as T without // SAFETY:).
When a pattern file disagrees with repos/effect/ source, trust the source — file an issue or open a PR to fix the pattern doc.