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oxlint-plugin-effect

prefer-effect-fn

Intent: an effectful function is Effect.fn("name"), and a named effect value has a span.

// ❌ no
const outcomeFor = (name: string) => Effect.gen(function* () { … }).pipe(Effect.catch(toFailed))
const refresh = Effect.gen(function* () { … })


// ✅ yes: extra combinators as arguments, not .pipe
const outcomeFor = Effect.fn("outcomeFor")(function* (name: string) { … }, Effect.catch(toFailed))
const refresh = Effect.gen(function* () { … }).pipe(Effect.withSpan("refresh"))

Trigger:

  • a declared function, a variable or an object member that only returns Effect.gen(…), even with .pipe;
  • a variable or an object member whose value is Effect.gen(…) without Effect.withSpan in its .pipe;
  • Effect.fn(body) without a name;
  • .pipe on Effect.fn(…)(…).

Exemptions and blind spots: Effect.gen inline as an argument (Layer.effect(Tag, Effect.gen(…)), Stream.unwrap, callbacks, it.effect). Recursive functions: see untraced-recursion.

Why: named stack traces and spans without wrapper functions. Combinators passed as arguments run inside the function’s span and receive its arguments: (effect, name) => effect.pipe(…).

Options: none

Fix: none