<A, E, R>(
predicate: (a: NoInfer<A>, i: number) => Effect<boolean, E, R>
): (elements: Iterable<A>) => Effect<Option<A>, E, R>
<A, E, R>(
elements: Iterable<A>,
predicate: (a: NoInfer<A>, i: number) => Effect<boolean, E, R>
): Effect<Option<A>, E, R>Returns the first element that satisfies an effectful predicate.
Details
The predicate receives the element and its index. Evaluation short-circuits as soon as an element matches.
Example (Finding the first successful match)
import { Effect } from "effect"
const program = Effect.findFirst([1, 2, 3, 4], (n) => Effect.succeed(n > 2))
Effect.runPromise(program).then(console.log)
// { _id: 'Option', _tag: 'Some', value: 3 }export const const findFirst: {
<A, E, R>(
predicate: (
a: NoInfer<A>,
i: number
) => Effect<boolean, E, R>
): (
elements: Iterable<A>
) => Effect<Option<A>, E, R>
<A, E, R>(
elements: Iterable<A>,
predicate: (
a: NoInfer<A>,
i: number
) => Effect<boolean, E, R>
): Effect<Option<A>, E, R>
}
Returns the first element that satisfies an effectful predicate.
Details
The predicate receives the element and its index. Evaluation short-circuits
as soon as an element matches.
Example (Finding the first successful match)
import { Effect } from "effect"
const program = Effect.findFirst([1, 2, 3, 4], (n) => Effect.succeed(n > 2))
Effect.runPromise(program).then(console.log)
// { _id: 'Option', _tag: 'Some', value: 3 }
findFirst: {
<function (type parameter) A in <A, E, R>(predicate: (a: NoInfer<A>, i: number) => Effect<boolean, E, R>): (elements: Iterable<A>) => Effect<Option<A>, E, R>A, function (type parameter) E in <A, E, R>(predicate: (a: NoInfer<A>, i: number) => Effect<boolean, E, R>): (elements: Iterable<A>) => Effect<Option<A>, E, R>E, function (type parameter) R in <A, E, R>(predicate: (a: NoInfer<A>, i: number) => Effect<boolean, E, R>): (elements: Iterable<A>) => Effect<Option<A>, E, R>R>(
predicate: (
a: NoInfer<A>,
i: number
) => Effect<boolean, E, R>
a: NoInfer<A>a: type NoInfer<A> = [A][A extends any ? 0 : never]Prevents TypeScript from inferring a type parameter from a specific
position.
When to use
Use when a function parameter must match an inferred type without becoming
an inference source.
Details
The parameter using NoInfer must still match the inferred type.
Example (Controlling inference)
import type { Types } from "effect"
declare function withDefault<T>(value: T, fallback: Types.NoInfer<T>): T
// T is inferred as "a" | "b" from the first argument only
const result = withDefault<"a" | "b">("a", "b")
NoInfer<function (type parameter) A in <A, E, R>(predicate: (a: NoInfer<A>, i: number) => Effect<boolean, E, R>): (elements: Iterable<A>) => Effect<Option<A>, E, R>A>, i: numberi: number) => 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<boolean, function (type parameter) E in <A, E, R>(predicate: (a: NoInfer<A>, i: number) => Effect<boolean, E, R>): (elements: Iterable<A>) => Effect<Option<A>, E, R>E, function (type parameter) R in <A, E, R>(predicate: (a: NoInfer<A>, i: number) => Effect<boolean, E, R>): (elements: Iterable<A>) => Effect<Option<A>, E, R>R>
): (elements: Iterable<A>elements: interface Iterable<T, TReturn = any, TNext = any>Iterable<function (type parameter) A in <A, E, R>(predicate: (a: NoInfer<A>, i: number) => Effect<boolean, E, R>): (elements: Iterable<A>) => Effect<Option<A>, E, R>A>) => 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<type Option<A> = None<A> | Some<A>The Option data type represents optional values. An Option<A> is either
Some<A>, containing a value of type A, or None, representing absence.
When to use
Use to represent initial values that may not yet exist
- Returning from partial functions (not defined for all inputs)
- Managing optional fields in data structures
Namespace containing utility types for Option.
When to use
Use to access type-level helpers associated with Option.
Option<function (type parameter) A in <A, E, R>(predicate: (a: NoInfer<A>, i: number) => Effect<boolean, E, R>): (elements: Iterable<A>) => Effect<Option<A>, E, R>A>, function (type parameter) E in <A, E, R>(predicate: (a: NoInfer<A>, i: number) => Effect<boolean, E, R>): (elements: Iterable<A>) => Effect<Option<A>, E, R>E, function (type parameter) R in <A, E, R>(predicate: (a: NoInfer<A>, i: number) => Effect<boolean, E, R>): (elements: Iterable<A>) => Effect<Option<A>, E, R>R>
<function (type parameter) A in <A, E, R>(elements: Iterable<A>, predicate: (a: NoInfer<A>, i: number) => Effect<boolean, E, R>): Effect<Option<A>, E, R>A, function (type parameter) E in <A, E, R>(elements: Iterable<A>, predicate: (a: NoInfer<A>, i: number) => Effect<boolean, E, R>): Effect<Option<A>, E, R>E, function (type parameter) R in <A, E, R>(elements: Iterable<A>, predicate: (a: NoInfer<A>, i: number) => Effect<boolean, E, R>): Effect<Option<A>, E, R>R>(
elements: Iterable<A>elements: interface Iterable<T, TReturn = any, TNext = any>Iterable<function (type parameter) A in <A, E, R>(elements: Iterable<A>, predicate: (a: NoInfer<A>, i: number) => Effect<boolean, E, R>): Effect<Option<A>, E, R>A>,
predicate: (
a: NoInfer<A>,
i: number
) => Effect<boolean, E, R>
a: NoInfer<A>a: type NoInfer<A> = [A][A extends any ? 0 : never]Prevents TypeScript from inferring a type parameter from a specific
position.
When to use
Use when a function parameter must match an inferred type without becoming
an inference source.
Details
The parameter using NoInfer must still match the inferred type.
Example (Controlling inference)
import type { Types } from "effect"
declare function withDefault<T>(value: T, fallback: Types.NoInfer<T>): T
// T is inferred as "a" | "b" from the first argument only
const result = withDefault<"a" | "b">("a", "b")
NoInfer<function (type parameter) A in <A, E, R>(elements: Iterable<A>, predicate: (a: NoInfer<A>, i: number) => Effect<boolean, E, R>): Effect<Option<A>, E, R>A>, i: numberi: number) => 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<boolean, function (type parameter) E in <A, E, R>(elements: Iterable<A>, predicate: (a: NoInfer<A>, i: number) => Effect<boolean, E, R>): Effect<Option<A>, E, R>E, function (type parameter) R in <A, E, R>(elements: Iterable<A>, predicate: (a: NoInfer<A>, i: number) => Effect<boolean, E, R>): Effect<Option<A>, E, R>R>
): 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<type Option<A> = None<A> | Some<A>The Option data type represents optional values. An Option<A> is either
Some<A>, containing a value of type A, or None, representing absence.
When to use
Use to represent initial values that may not yet exist
- Returning from partial functions (not defined for all inputs)
- Managing optional fields in data structures
Namespace containing utility types for Option.
When to use
Use to access type-level helpers associated with Option.
Option<function (type parameter) A in <A, E, R>(elements: Iterable<A>, predicate: (a: NoInfer<A>, i: number) => Effect<boolean, E, R>): Effect<Option<A>, E, R>A>, function (type parameter) E in <A, E, R>(elements: Iterable<A>, predicate: (a: NoInfer<A>, i: number) => Effect<boolean, E, R>): Effect<Option<A>, E, R>E, function (type parameter) R in <A, E, R>(elements: Iterable<A>, predicate: (a: NoInfer<A>, i: number) => Effect<boolean, E, R>): Effect<Option<A>, E, R>R>
} = import internalinternal.const findFirst: {
<A, E, R>(
predicate: (
a: NoInfer<A>,
i: number
) => Effect.Effect<boolean, E, R>
): (
elements: Iterable<A>
) => Effect.Effect<Option.Option<A>, E, R>
<A, E, R>(
elements: Iterable<A>,
predicate: (
a: NoInfer<A>,
i: number
) => Effect.Effect<boolean, E, R>
): Effect.Effect<Option.Option<A>, E, R>
}