Hyperlinkv0.8.0-beta.28

← Effect

Effect.updateServiceconsteffect/Effect.ts:6160
<I, A>(service: Context.Key<I, A>, f: (value: A) => A): <XA, E, R>(
  self: Effect<XA, E, R>
) => Effect<XA, E, R | I>
<XA, E, R, I, A>(
  self: Effect<XA, E, R>,
  service: Context.Key<I, A>,
  f: (value: A) => A
): Effect<XA, E, R | I>

Runs an effect with a service implementation transformed by the provided function.

Details

The service must be available in the effect's context; updateService replaces it for the wrapped effect with the value returned by the updater.

Example (Replacing a service for one effect)

import { Console, Context, Effect } from "effect"

// Define a counter service
const Counter = Context.Service<{ count: number }>("Counter")

const program = Effect.gen(function*() {
  const updatedCounter = yield* Effect.service(Counter)
  yield* Console.log(`Updated count: ${updatedCounter.count}`)
  return updatedCounter.count
}).pipe(
  Effect.updateService(Counter, (counter) => ({ count: counter.count + 1 }))
)

// Provide initial service and run
const result = Effect.provideService(program, Counter, { count: 0 })
Effect.runPromise(result).then(console.log)
// Output: Updated count: 1
// 1
context
Source effect/Effect.ts:616011 lines
export const updateService: {
  <I, A>(
    service: Context.Key<I, A>,
    f: (value: A) => A
  ): <XA, E, R>(self: Effect<XA, E, R>) => Effect<XA, E, R | I>
  <XA, E, R, I, A>(
    self: Effect<XA, E, R>,
    service: Context.Key<I, A>,
    f: (value: A) => A
  ): Effect<XA, E, R | I>
} = internal.updateService