5 replies

The purpose of `Tag.of()` in `Effect.provideService`

What is the purpose of

Tag.of()

Tag.of()

Tag.of()

Tag.of()?

in

Effect.provideService

Effect.provideService

Effect.provideService

Effect.provideService for example:

interface Random {
  readonly next: () => Effect.Effect<never, never, number>;
}
const Random = Context.Tag<Random>();
Effect.provideService(
  Random,
  // works
  Random.of({ next: () => Effect.succeed(Math.random()) })
  // just the value also works
  // { next: () => Effect.succeed(Math.random()) }
)

interface Random {
  readonly next: () => Effect.Effect<never, never, number>;
}
const Random = Context.Tag<Random>();
Effect.provideService(
  Random,
  // works
  Random.of({ next: () => Effect.succeed(Math.random()) })
  // just the value also works
  // { next: () => Effect.succeed(Math.random()) }
)

interface Random {
  readonly next: () => Effect.Effect<never, never, number>;
}
const Random = Context.Tag<Random>();
Effect.provideService(
  Random,
  // works
  Random.of({ next: () => Effect.succeed(Math.random()) })
  // just the value also works
  // { next: () => Effect.succeed(Math.random()) }
)

interface Random {
  readonly next: () => Effect.Effect<never, never, number>;
}
const Random = Context.Tag<Random>();
Effect.provideService(
  Random,
  // works
  Random.of({ next: () => Effect.succeed(Math.random()) })
  // just the value also works
  // { next: () => Effect.succeed(Math.random()) }
)

the source code is just

of(self: Service): Service {
    return self
}

of(self: Service): Service {
    return self
}

of(self: Service): Service {
    return self
}

of(self: Service): Service {
    return self
}

So is it just a explicitness thing? Is it 'idiomatic' effect to always use

Tag.of()

Tag.of()

Tag.of()

Tag.of() when providing an instance of the tagged type?

The purpose of `Tag.of()` in `Effect.provideService`

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