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Effect Documentation

Default Services

Effect comes equipped with five pre-built services:

type DefaultServices = Clock | ConfigProvider | Console | Random | Tracer

When we employ these services, there’s no need to explicitly provide their implementations. Effect automatically supplies live versions of these services to our effects, sparing us from manual setup.

Example (Using Clock and Console)

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import { 
import Effect
Effect, 
import Clock
Clock, 
import Console
Console } from "effect"
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//      ┌─── Effect<void, never, never>
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//      ▼
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const 
const program: Effect.Effect<void, never, never>
program = 
import Effect
Effect.
const gen: <YieldWrap<Effect.Effect<void, never, never>>, void>(f: (resume: Effect.Adapter) => Generator<YieldWrap<Effect.Effect<void, never, never>>, void, never>) => Effect.Effect<...> (+1 overload)
gen(function* () {
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  const 
const now: number
now = yield* 
import Clock
Clock.
const currentTimeMillis: Effect.Effect<number, never, never>
currentTimeMillis
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  yield* 
import Console
Console.
const log: (...args: ReadonlyArray<any>) => Effect.Effect<void>
log(`Application started at ${new 
var Date: DateConstructor
new (value: number | string | Date) => Date (+3 overloads)
Date(
const now: number
now)}`)
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})

As you can observe, even if our program utilizes both Clock and Console, the Requirements parameter, representing the services required for the effect to execute, remains set to never. Effect takes care of handling these services seamlessly for us.