<R>(): <A, E, R2 extends R>(effect: Effect<A, E, R2>) => Effect<A, E, R2>Ensures that an effect's requirements type extends a given type R.
Details
This helper is checked at compile time and does not change the effect's runtime behavior.
Example (Constraining the services type)
import { Effect } from "effect"
// Define a constraint that requires a string as the requirements type
const satisfiesStringServices = Effect.satisfiesServicesType<string>()
// This works - effect requires string
const validEffect: Effect.Effect<number, never, "config"> = Effect.succeed(42)
const constrainedEffect = satisfiesStringServices(validEffect)
// This would cause a TypeScript compilation error if uncommented:
// const invalidEffect: Effect.Effect<number, never, number> = Effect.succeed(42)
// const constrainedInvalid = satisfiesStringServices(invalidEffect)export const const satisfiesServicesType: <R>() => <
A,
E,
R2 extends R
>(
effect: Effect<A, E, R2>
) => Effect<A, E, R2>
Ensures that an effect's requirements type extends a given type R.
Details
This helper is checked at compile time and does not change the effect's
runtime behavior.
Example (Constraining the services type)
import { Effect } from "effect"
// Define a constraint that requires a string as the requirements type
const satisfiesStringServices = Effect.satisfiesServicesType<string>()
// This works - effect requires string
const validEffect: Effect.Effect<number, never, "config"> = Effect.succeed(42)
const constrainedEffect = satisfiesStringServices(validEffect)
// This would cause a TypeScript compilation error if uncommented:
// const invalidEffect: Effect.Effect<number, never, number> = Effect.succeed(42)
// const constrainedInvalid = satisfiesStringServices(invalidEffect)
satisfiesServicesType = <function (type parameter) R in <R>(): <A, E, R2 extends R>(effect: Effect<A, E, R2>) => Effect<A, E, R2>R>() => <function (type parameter) A in <A, E, R2 extends R>(effect: Effect<A, E, R2>): Effect<A, E, R2>A, function (type parameter) E in <A, E, R2 extends R>(effect: Effect<A, E, R2>): Effect<A, E, R2>E, function (type parameter) R2 in <A, E, R2 extends R>(effect: Effect<A, E, R2>): Effect<A, E, R2>R2 extends function (type parameter) R in <R>(): <A, E, R2 extends R>(effect: Effect<A, E, R2>) => Effect<A, E, R2>R>(effect: Effect<A, E, R2>(parameter) effect: {
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
toString: () => string;
toJSON: () => unknown;
}
interface Effect<out A, out E = never, out R = never>The Effect interface defines a value that lazily describes a workflow or
job. The workflow requires some context R, and may fail with an error of
type E, or succeed with a value of type A.
When to use
Use when you need to represent a lazy, composable workflow that can require
services, fail with a typed error, or succeed with a typed value.
Details
Effect values model resourceful interaction with the outside world,
including synchronous, asynchronous, concurrent, and parallel interaction.
They use a fiber-based concurrency model, with built-in support for
scheduling, fine-grained interruption, structured concurrency, and high
scalability.
To run an Effect value, you need a Runtime, which is a type that is
capable of executing Effect values.
Effect<function (type parameter) A in <A, E, R2 extends R>(effect: Effect<A, E, R2>): Effect<A, E, R2>A, function (type parameter) E in <A, E, R2 extends R>(effect: Effect<A, E, R2>): Effect<A, E, R2>E, function (type parameter) R2 in <A, E, R2 extends R>(effect: Effect<A, E, R2>): Effect<A, E, R2>R2>): interface Effect<out A, out E = never, out R = never>The Effect interface defines a value that lazily describes a workflow or
job. The workflow requires some context R, and may fail with an error of
type E, or succeed with a value of type A.
When to use
Use when you need to represent a lazy, composable workflow that can require
services, fail with a typed error, or succeed with a typed value.
Details
Effect values model resourceful interaction with the outside world,
including synchronous, asynchronous, concurrent, and parallel interaction.
They use a fiber-based concurrency model, with built-in support for
scheduling, fine-grained interruption, structured concurrency, and high
scalability.
To run an Effect value, you need a Runtime, which is a type that is
capable of executing Effect values.
Effect<function (type parameter) A in <A, E, R2 extends R>(effect: Effect<A, E, R2>): Effect<A, E, R2>A, function (type parameter) E in <A, E, R2 extends R>(effect: Effect<A, E, R2>): Effect<A, E, R2>E, function (type parameter) R2 in <A, E, R2 extends R>(effect: Effect<A, E, R2>): Effect<A, E, R2>R2> => effect: Effect<A, E, R2>(parameter) effect: {
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
toString: () => string;
toJSON: () => unknown;
}