<K extends string | symbol, V, V2 extends V>(
refinement: (value: NoInfer<V>, key: NoInfer<K>) => value is V2
): (self: ReadonlyRecord<K, V>) => Option.Option<[K, V2]>
<K extends string | symbol, V>(
predicate: (value: NoInfer<V>, key: NoInfer<K>) => boolean
): (self: ReadonlyRecord<K, V>) => Option.Option<[K, V]>
<K extends string | symbol, V, V2 extends V>(
self: ReadonlyRecord<K, V>,
refinement: (value: NoInfer<V>, key: NoInfer<K>) => value is V2
): Option.Option<[K, V2]>
<K extends string | symbol, V>(
self: ReadonlyRecord<K, V>,
predicate: (value: NoInfer<V>, key: NoInfer<K>) => boolean
): Option.Option<[K, V]>Returns the first entry that satisfies the specified
predicate, or None if no such entry exists.
Example (Finding the first matching entry)
import { Record } from "effect"
const record = { a: 1, b: 2, c: 3 }
const result = Record.findFirst(
record,
(value, key) => value > 1 && key !== "b"
)
console.log(result) // Option.Some(["c", 3])export const const findFirst: {
<K extends string | symbol, V, V2 extends V>(
refinement: (
value: NoInfer<V>,
key: NoInfer<K>
) => value is V2
): (
self: ReadonlyRecord<K, V>
) => Option.Option<[K, V2]>
<K extends string | symbol, V>(
predicate: (
value: NoInfer<V>,
key: NoInfer<K>
) => boolean
): (
self: ReadonlyRecord<K, V>
) => Option.Option<[K, V]>
<K extends string | symbol, V, V2 extends V>(
self: ReadonlyRecord<K, V>,
refinement: (
value: NoInfer<V>,
key: NoInfer<K>
) => value is V2
): Option.Option<[K, V2]>
<K extends string | symbol, V>(
self: ReadonlyRecord<K, V>,
predicate: (
value: NoInfer<V>,
key: NoInfer<K>
) => boolean
): Option.Option<[K, V]>
}
Returns the first entry that satisfies the specified
predicate, or None if no such entry exists.
Example (Finding the first matching entry)
import { Record } from "effect"
const record = { a: 1, b: 2, c: 3 }
const result = Record.findFirst(
record,
(value, key) => value > 1 && key !== "b"
)
console.log(result) // Option.Some(["c", 3])
findFirst: {
<function (type parameter) K in <K extends string | symbol, V, V2 extends V>(refinement: (value: NoInfer<V>, key: NoInfer<K>) => value is V2): (self: ReadonlyRecord<K, V>) => Option.Option<[K, V2]>K extends string | symbol, function (type parameter) V in <K extends string | symbol, V, V2 extends V>(refinement: (value: NoInfer<V>, key: NoInfer<K>) => value is V2): (self: ReadonlyRecord<K, V>) => Option.Option<[K, V2]>V, function (type parameter) V2 in <K extends string | symbol, V, V2 extends V>(refinement: (value: NoInfer<V>, key: NoInfer<K>) => value is V2): (self: ReadonlyRecord<K, V>) => Option.Option<[K, V2]>V2 extends function (type parameter) V in <K extends string | symbol, V, V2 extends V>(refinement: (value: NoInfer<V>, key: NoInfer<K>) => value is V2): (self: ReadonlyRecord<K, V>) => Option.Option<[K, V2]>V>(
refinement: (
value: NoInfer<V>,
key: NoInfer<K>
) => value is V2
value: NoInfer<V>value: 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) V in <K extends string | symbol, V, V2 extends V>(refinement: (value: NoInfer<V>, key: NoInfer<K>) => value is V2): (self: ReadonlyRecord<K, V>) => Option.Option<[K, V2]>V>, key: NoInfer<K>key: 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) K in <K extends string | symbol, V, V2 extends V>(refinement: (value: NoInfer<V>, key: NoInfer<K>) => value is V2): (self: ReadonlyRecord<K, V>) => Option.Option<[K, V2]>K>) => value: NoInfer<V>value is function (type parameter) V2 in <K extends string | symbol, V, V2 extends V>(refinement: (value: NoInfer<V>, key: NoInfer<K>) => value is V2): (self: ReadonlyRecord<K, V>) => Option.Option<[K, V2]>V2
): (self: ReadonlyRecord<K, V>self: type ReadonlyRecord<in out K extends string | symbol, out A> = { readonly [P in K]: A; }Represents a readonly record with keys of type K and values of type A.
This is the foundational type for immutable key-value mappings in Effect.
Example (Defining a readonly record type)
import type { Record } from "effect"
// Creating a readonly record type
type UserRecord = Record.ReadonlyRecord<"name" | "age", string | number>
const user: UserRecord = {
name: "John",
age: 30
}
Namespace containing utility types for working with readonly records.
These types help with type-level operations on record keys and values.
Example (Using readonly record helper types)
import type { Record } from "effect"
// Using NonLiteralKey to convert literal keys to generic types
type GenericKey = Record.ReadonlyRecord.NonLiteralKey<"foo" | "bar"> // string
// Using IntersectKeys to find common keys between record types
type CommonKeys = Record.ReadonlyRecord.IntersectKeys<"a" | "b", "b" | "c"> // "b"
ReadonlyRecord<function (type parameter) K in <K extends string | symbol, V, V2 extends V>(refinement: (value: NoInfer<V>, key: NoInfer<K>) => value is V2): (self: ReadonlyRecord<K, V>) => Option.Option<[K, V2]>K, function (type parameter) V in <K extends string | symbol, V, V2 extends V>(refinement: (value: NoInfer<V>, key: NoInfer<K>) => value is V2): (self: ReadonlyRecord<K, V>) => Option.Option<[K, V2]>V>) => import OptionOption.type Option.Option = /*unresolved*/ anyOption<[function (type parameter) K in <K extends string | symbol, V, V2 extends V>(refinement: (value: NoInfer<V>, key: NoInfer<K>) => value is V2): (self: ReadonlyRecord<K, V>) => Option.Option<[K, V2]>K, function (type parameter) V2 in <K extends string | symbol, V, V2 extends V>(refinement: (value: NoInfer<V>, key: NoInfer<K>) => value is V2): (self: ReadonlyRecord<K, V>) => Option.Option<[K, V2]>V2]>
<function (type parameter) K in <K extends string | symbol, V>(predicate: (value: NoInfer<V>, key: NoInfer<K>) => boolean): (self: ReadonlyRecord<K, V>) => Option.Option<[K, V]>K extends string | symbol, function (type parameter) V in <K extends string | symbol, V>(predicate: (value: NoInfer<V>, key: NoInfer<K>) => boolean): (self: ReadonlyRecord<K, V>) => Option.Option<[K, V]>V>(
predicate: (
value: NoInfer<V>,
key: NoInfer<K>
) => boolean
value: NoInfer<V>value: 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) V in <K extends string | symbol, V>(predicate: (value: NoInfer<V>, key: NoInfer<K>) => boolean): (self: ReadonlyRecord<K, V>) => Option.Option<[K, V]>V>, key: NoInfer<K>key: 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) K in <K extends string | symbol, V>(predicate: (value: NoInfer<V>, key: NoInfer<K>) => boolean): (self: ReadonlyRecord<K, V>) => Option.Option<[K, V]>K>) => boolean
): (self: ReadonlyRecord<K, V>self: type ReadonlyRecord<in out K extends string | symbol, out A> = { readonly [P in K]: A; }Represents a readonly record with keys of type K and values of type A.
This is the foundational type for immutable key-value mappings in Effect.
Example (Defining a readonly record type)
import type { Record } from "effect"
// Creating a readonly record type
type UserRecord = Record.ReadonlyRecord<"name" | "age", string | number>
const user: UserRecord = {
name: "John",
age: 30
}
Namespace containing utility types for working with readonly records.
These types help with type-level operations on record keys and values.
Example (Using readonly record helper types)
import type { Record } from "effect"
// Using NonLiteralKey to convert literal keys to generic types
type GenericKey = Record.ReadonlyRecord.NonLiteralKey<"foo" | "bar"> // string
// Using IntersectKeys to find common keys between record types
type CommonKeys = Record.ReadonlyRecord.IntersectKeys<"a" | "b", "b" | "c"> // "b"
ReadonlyRecord<function (type parameter) K in <K extends string | symbol, V>(predicate: (value: NoInfer<V>, key: NoInfer<K>) => boolean): (self: ReadonlyRecord<K, V>) => Option.Option<[K, V]>K, function (type parameter) V in <K extends string | symbol, V>(predicate: (value: NoInfer<V>, key: NoInfer<K>) => boolean): (self: ReadonlyRecord<K, V>) => Option.Option<[K, V]>V>) => import OptionOption.type Option.Option = /*unresolved*/ anyOption<[function (type parameter) K in <K extends string | symbol, V>(predicate: (value: NoInfer<V>, key: NoInfer<K>) => boolean): (self: ReadonlyRecord<K, V>) => Option.Option<[K, V]>K, function (type parameter) V in <K extends string | symbol, V>(predicate: (value: NoInfer<V>, key: NoInfer<K>) => boolean): (self: ReadonlyRecord<K, V>) => Option.Option<[K, V]>V]>
<function (type parameter) K in <K extends string | symbol, V, V2 extends V>(self: ReadonlyRecord<K, V>, refinement: (value: NoInfer<V>, key: NoInfer<K>) => value is V2): Option.Option<[K, V2]>K extends string | symbol, function (type parameter) V in <K extends string | symbol, V, V2 extends V>(self: ReadonlyRecord<K, V>, refinement: (value: NoInfer<V>, key: NoInfer<K>) => value is V2): Option.Option<[K, V2]>V, function (type parameter) V2 in <K extends string | symbol, V, V2 extends V>(self: ReadonlyRecord<K, V>, refinement: (value: NoInfer<V>, key: NoInfer<K>) => value is V2): Option.Option<[K, V2]>V2 extends function (type parameter) V in <K extends string | symbol, V, V2 extends V>(self: ReadonlyRecord<K, V>, refinement: (value: NoInfer<V>, key: NoInfer<K>) => value is V2): Option.Option<[K, V2]>V>(
self: ReadonlyRecord<K, V>self: type ReadonlyRecord<in out K extends string | symbol, out A> = { readonly [P in K]: A; }Represents a readonly record with keys of type K and values of type A.
This is the foundational type for immutable key-value mappings in Effect.
Example (Defining a readonly record type)
import type { Record } from "effect"
// Creating a readonly record type
type UserRecord = Record.ReadonlyRecord<"name" | "age", string | number>
const user: UserRecord = {
name: "John",
age: 30
}
Namespace containing utility types for working with readonly records.
These types help with type-level operations on record keys and values.
Example (Using readonly record helper types)
import type { Record } from "effect"
// Using NonLiteralKey to convert literal keys to generic types
type GenericKey = Record.ReadonlyRecord.NonLiteralKey<"foo" | "bar"> // string
// Using IntersectKeys to find common keys between record types
type CommonKeys = Record.ReadonlyRecord.IntersectKeys<"a" | "b", "b" | "c"> // "b"
ReadonlyRecord<function (type parameter) K in <K extends string | symbol, V, V2 extends V>(self: ReadonlyRecord<K, V>, refinement: (value: NoInfer<V>, key: NoInfer<K>) => value is V2): Option.Option<[K, V2]>K, function (type parameter) V in <K extends string | symbol, V, V2 extends V>(self: ReadonlyRecord<K, V>, refinement: (value: NoInfer<V>, key: NoInfer<K>) => value is V2): Option.Option<[K, V2]>V>,
refinement: (
value: NoInfer<V>,
key: NoInfer<K>
) => value is V2
value: NoInfer<V>value: 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) V in <K extends string | symbol, V, V2 extends V>(self: ReadonlyRecord<K, V>, refinement: (value: NoInfer<V>, key: NoInfer<K>) => value is V2): Option.Option<[K, V2]>V>, key: NoInfer<K>key: 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) K in <K extends string | symbol, V, V2 extends V>(self: ReadonlyRecord<K, V>, refinement: (value: NoInfer<V>, key: NoInfer<K>) => value is V2): Option.Option<[K, V2]>K>) => value: NoInfer<V>value is function (type parameter) V2 in <K extends string | symbol, V, V2 extends V>(self: ReadonlyRecord<K, V>, refinement: (value: NoInfer<V>, key: NoInfer<K>) => value is V2): Option.Option<[K, V2]>V2
): import OptionOption.type Option.Option = /*unresolved*/ anyOption<[function (type parameter) K in <K extends string | symbol, V, V2 extends V>(self: ReadonlyRecord<K, V>, refinement: (value: NoInfer<V>, key: NoInfer<K>) => value is V2): Option.Option<[K, V2]>K, function (type parameter) V2 in <K extends string | symbol, V, V2 extends V>(self: ReadonlyRecord<K, V>, refinement: (value: NoInfer<V>, key: NoInfer<K>) => value is V2): Option.Option<[K, V2]>V2]>
<function (type parameter) K in <K extends string | symbol, V>(self: ReadonlyRecord<K, V>, predicate: (value: NoInfer<V>, key: NoInfer<K>) => boolean): Option.Option<[K, V]>K extends string | symbol, function (type parameter) V in <K extends string | symbol, V>(self: ReadonlyRecord<K, V>, predicate: (value: NoInfer<V>, key: NoInfer<K>) => boolean): Option.Option<[K, V]>V>(
self: ReadonlyRecord<K, V>self: type ReadonlyRecord<in out K extends string | symbol, out A> = { readonly [P in K]: A; }Represents a readonly record with keys of type K and values of type A.
This is the foundational type for immutable key-value mappings in Effect.
Example (Defining a readonly record type)
import type { Record } from "effect"
// Creating a readonly record type
type UserRecord = Record.ReadonlyRecord<"name" | "age", string | number>
const user: UserRecord = {
name: "John",
age: 30
}
Namespace containing utility types for working with readonly records.
These types help with type-level operations on record keys and values.
Example (Using readonly record helper types)
import type { Record } from "effect"
// Using NonLiteralKey to convert literal keys to generic types
type GenericKey = Record.ReadonlyRecord.NonLiteralKey<"foo" | "bar"> // string
// Using IntersectKeys to find common keys between record types
type CommonKeys = Record.ReadonlyRecord.IntersectKeys<"a" | "b", "b" | "c"> // "b"
ReadonlyRecord<function (type parameter) K in <K extends string | symbol, V>(self: ReadonlyRecord<K, V>, predicate: (value: NoInfer<V>, key: NoInfer<K>) => boolean): Option.Option<[K, V]>K, function (type parameter) V in <K extends string | symbol, V>(self: ReadonlyRecord<K, V>, predicate: (value: NoInfer<V>, key: NoInfer<K>) => boolean): Option.Option<[K, V]>V>,
predicate: (
value: NoInfer<V>,
key: NoInfer<K>
) => boolean
value: NoInfer<V>value: 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) V in <K extends string | symbol, V>(self: ReadonlyRecord<K, V>, predicate: (value: NoInfer<V>, key: NoInfer<K>) => boolean): Option.Option<[K, V]>V>, key: NoInfer<K>key: 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) K in <K extends string | symbol, V>(self: ReadonlyRecord<K, V>, predicate: (value: NoInfer<V>, key: NoInfer<K>) => boolean): Option.Option<[K, V]>K>) => boolean
): import OptionOption.type Option.Option = /*unresolved*/ anyOption<[function (type parameter) K in <K extends string | symbol, V>(self: ReadonlyRecord<K, V>, predicate: (value: NoInfer<V>, key: NoInfer<K>) => boolean): Option.Option<[K, V]>K, function (type parameter) V in <K extends string | symbol, V>(self: ReadonlyRecord<K, V>, predicate: (value: NoInfer<V>, key: NoInfer<K>) => boolean): Option.Option<[K, V]>V]>
} = import dualdual(
2,
<function (type parameter) K in <K extends string | symbol, V>(self: ReadonlyRecord<K, V>, f: (value: V, key: K) => boolean): Option.Option<[K, V]>K extends string | symbol, function (type parameter) V in <K extends string | symbol, V>(self: ReadonlyRecord<K, V>, f: (value: V, key: K) => boolean): Option.Option<[K, V]>V>(
self: ReadonlyRecord<K, V>self: type ReadonlyRecord<in out K extends string | symbol, out A> = { readonly [P in K]: A; }Represents a readonly record with keys of type K and values of type A.
This is the foundational type for immutable key-value mappings in Effect.
Example (Defining a readonly record type)
import type { Record } from "effect"
// Creating a readonly record type
type UserRecord = Record.ReadonlyRecord<"name" | "age", string | number>
const user: UserRecord = {
name: "John",
age: 30
}
Namespace containing utility types for working with readonly records.
These types help with type-level operations on record keys and values.
Example (Using readonly record helper types)
import type { Record } from "effect"
// Using NonLiteralKey to convert literal keys to generic types
type GenericKey = Record.ReadonlyRecord.NonLiteralKey<"foo" | "bar"> // string
// Using IntersectKeys to find common keys between record types
type CommonKeys = Record.ReadonlyRecord.IntersectKeys<"a" | "b", "b" | "c"> // "b"
ReadonlyRecord<function (type parameter) K in <K extends string | symbol, V>(self: ReadonlyRecord<K, V>, f: (value: V, key: K) => boolean): Option.Option<[K, V]>K, function (type parameter) V in <K extends string | symbol, V>(self: ReadonlyRecord<K, V>, f: (value: V, key: K) => boolean): Option.Option<[K, V]>V>,
f: (value: V, key: K) => booleanf: (value: Vvalue: function (type parameter) V in <K extends string | symbol, V>(self: ReadonlyRecord<K, V>, f: (value: V, key: K) => boolean): Option.Option<[K, V]>V, key: K extends string | symbolkey: function (type parameter) K in <K extends string | symbol, V>(self: ReadonlyRecord<K, V>, f: (value: V, key: K) => boolean): Option.Option<[K, V]>K) => boolean
): import OptionOption.type Option.Option = /*unresolved*/ anyOption<[function (type parameter) K in <K extends string | symbol, V>(self: ReadonlyRecord<K, V>, f: (value: V, key: K) => boolean): Option.Option<[K, V]>K, function (type parameter) V in <K extends string | symbol, V>(self: ReadonlyRecord<K, V>, f: (value: V, key: K) => boolean): Option.Option<[K, V]>V]> => {
const const k: (K & string)[]k = const keys: <
K extends string | symbol,
A
>(
self: ReadonlyRecord<K, A>
) => Array<K & string>
Retrieves the keys of a given record as an array.
Example (Getting record keys)
import { Record } from "effect"
import * as assert from "node:assert"
assert.deepStrictEqual(Record.keys({ a: 1, b: 2, c: 3 }), ["a", "b", "c"])
keys(self: ReadonlyRecord<K, V>self)
for (let let i: numberi = 0; let i: numberi < const k: (K & string)[]k.Array<T>.length: numberGets or sets the length of the array. This is a number one higher than the highest index in the array.
length; let i: numberi++) {
const const key: K & stringkey = const k: (K & string)[]k[let i: numberi]
if (f: (value: V, key: K) => booleanf(self: ReadonlyRecord<K, V>self[const key: K & stringkey], const key: K & stringkey)) {
return import OptionOption.some([const key: stringkey, self: ReadonlyRecord<K, V>self[const key: K & stringkey]])
}
}
return import OptionOption.none()
}
)