<K extends string | symbol, A, B>(key: NoInfer<K>, f: (a: A) => B): (
self: ReadonlyRecord<K, A>
) => Option.Option<Record<K, A | B>>
<K extends string | symbol, A, B>(
self: ReadonlyRecord<K, A>,
key: NoInfer<K>,
f: (a: A) => B
): Option.Option<Record<K, A | B>>Applies a function to the element at the specified key safely, creating a new record,
or return Option.none() if the key doesn't exist.
Example (Modifying a value at a key)
import { Record } from "effect"
const f = (x: number) => x * 2
const input: Record<string, number> = { a: 3 }
Record.modify(input, "a", f) // Option.some({ a: 6 })
Record.modify(input, "b", f) // Option.none()mutations
Source effect/Record.ts:46421 lines
export const const modify: {
<K extends string | symbol, A, B>(
key: NoInfer<K>,
f: (a: A) => B
): (
self: ReadonlyRecord<K, A>
) => Option.Option<Record<K, A | B>>
<K extends string | symbol, A, B>(
self: ReadonlyRecord<K, A>,
key: NoInfer<K>,
f: (a: A) => B
): Option.Option<Record<K, A | B>>
}
Applies a function to the element at the specified key safely, creating a new record,
or return Option.none() if the key doesn't exist.
Example (Modifying a value at a key)
import { Record } from "effect"
const f = (x: number) => x * 2
const input: Record<string, number> = { a: 3 }
Record.modify(input, "a", f) // Option.some({ a: 6 })
Record.modify(input, "b", f) // Option.none()
modify: {
<function (type parameter) K in <K extends string | symbol, A, B>(key: NoInfer<K>, f: (a: A) => B): (self: ReadonlyRecord<K, A>) => Option.Option<Record<K, A | B>>K extends string | symbol, function (type parameter) A in <K extends string | symbol, A, B>(key: NoInfer<K>, f: (a: A) => B): (self: ReadonlyRecord<K, A>) => Option.Option<Record<K, A | B>>A, function (type parameter) B in <K extends string | symbol, A, B>(key: NoInfer<K>, f: (a: A) => B): (self: ReadonlyRecord<K, A>) => Option.Option<Record<K, A | B>>B>(
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, A, B>(key: NoInfer<K>, f: (a: A) => B): (self: ReadonlyRecord<K, A>) => Option.Option<Record<K, A | B>>K>,
f: (a: A) => Bf: (a: Aa: function (type parameter) A in <K extends string | symbol, A, B>(key: NoInfer<K>, f: (a: A) => B): (self: ReadonlyRecord<K, A>) => Option.Option<Record<K, A | B>>A) => function (type parameter) B in <K extends string | symbol, A, B>(key: NoInfer<K>, f: (a: A) => B): (self: ReadonlyRecord<K, A>) => Option.Option<Record<K, A | B>>B
): (self: ReadonlyRecord<K, A>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, A, B>(key: NoInfer<K>, f: (a: A) => B): (self: ReadonlyRecord<K, A>) => Option.Option<Record<K, A | B>>K, function (type parameter) A in <K extends string | symbol, A, B>(key: NoInfer<K>, f: (a: A) => B): (self: ReadonlyRecord<K, A>) => Option.Option<Record<K, A | B>>A>) => import OptionOption.type Option.Option = /*unresolved*/ anyOption<type Record<K extends keyof any, T> = {
[P in K]: T
}
Construct a type with a set of properties K of type T
Record<function (type parameter) K in <K extends string | symbol, A, B>(key: NoInfer<K>, f: (a: A) => B): (self: ReadonlyRecord<K, A>) => Option.Option<Record<K, A | B>>K, function (type parameter) A in <K extends string | symbol, A, B>(key: NoInfer<K>, f: (a: A) => B): (self: ReadonlyRecord<K, A>) => Option.Option<Record<K, A | B>>A | function (type parameter) B in <K extends string | symbol, A, B>(key: NoInfer<K>, f: (a: A) => B): (self: ReadonlyRecord<K, A>) => Option.Option<Record<K, A | B>>B>>
<function (type parameter) K in <K extends string | symbol, A, B>(self: ReadonlyRecord<K, A>, key: NoInfer<K>, f: (a: A) => B): Option.Option<Record<K, A | B>>K extends string | symbol, function (type parameter) A in <K extends string | symbol, A, B>(self: ReadonlyRecord<K, A>, key: NoInfer<K>, f: (a: A) => B): Option.Option<Record<K, A | B>>A, function (type parameter) B in <K extends string | symbol, A, B>(self: ReadonlyRecord<K, A>, key: NoInfer<K>, f: (a: A) => B): Option.Option<Record<K, A | B>>B>(
self: ReadonlyRecord<K, A>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, A, B>(self: ReadonlyRecord<K, A>, key: NoInfer<K>, f: (a: A) => B): Option.Option<Record<K, A | B>>K, function (type parameter) A in <K extends string | symbol, A, B>(self: ReadonlyRecord<K, A>, key: NoInfer<K>, f: (a: A) => B): Option.Option<Record<K, A | B>>A>,
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, A, B>(self: ReadonlyRecord<K, A>, key: NoInfer<K>, f: (a: A) => B): Option.Option<Record<K, A | B>>K>,
f: (a: A) => Bf: (a: Aa: function (type parameter) A in <K extends string | symbol, A, B>(self: ReadonlyRecord<K, A>, key: NoInfer<K>, f: (a: A) => B): Option.Option<Record<K, A | B>>A) => function (type parameter) B in <K extends string | symbol, A, B>(self: ReadonlyRecord<K, A>, key: NoInfer<K>, f: (a: A) => B): Option.Option<Record<K, A | B>>B
): import OptionOption.type Option.Option = /*unresolved*/ anyOption<type Record<K extends keyof any, T> = {
[P in K]: T
}
Construct a type with a set of properties K of type T
Record<function (type parameter) K in <K extends string | symbol, A, B>(self: ReadonlyRecord<K, A>, key: NoInfer<K>, f: (a: A) => B): Option.Option<Record<K, A | B>>K, function (type parameter) A in <K extends string | symbol, A, B>(self: ReadonlyRecord<K, A>, key: NoInfer<K>, f: (a: A) => B): Option.Option<Record<K, A | B>>A | function (type parameter) B in <K extends string | symbol, A, B>(self: ReadonlyRecord<K, A>, key: NoInfer<K>, f: (a: A) => B): Option.Option<Record<K, A | B>>B>>
} = import dualdual(
3,
<function (type parameter) K in <K extends string | symbol, A, B>(self: ReadonlyRecord<K, A>, key: NoInfer<K>, f: (a: A) => B): Option.Option<Record<K, A | B>>K extends string | symbol, function (type parameter) A in <K extends string | symbol, A, B>(self: ReadonlyRecord<K, A>, key: NoInfer<K>, f: (a: A) => B): Option.Option<Record<K, A | B>>A, function (type parameter) B in <K extends string | symbol, A, B>(self: ReadonlyRecord<K, A>, key: NoInfer<K>, f: (a: A) => B): Option.Option<Record<K, A | B>>B>(
self: ReadonlyRecord<K, A>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, A, B>(self: ReadonlyRecord<K, A>, key: NoInfer<K>, f: (a: A) => B): Option.Option<Record<K, A | B>>K, function (type parameter) A in <K extends string | symbol, A, B>(self: ReadonlyRecord<K, A>, key: NoInfer<K>, f: (a: A) => B): Option.Option<Record<K, A | B>>A>,
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, A, B>(self: ReadonlyRecord<K, A>, key: NoInfer<K>, f: (a: A) => B): Option.Option<Record<K, A | B>>K>,
f: (a: A) => Bf: (a: Aa: function (type parameter) A in <K extends string | symbol, A, B>(self: ReadonlyRecord<K, A>, key: NoInfer<K>, f: (a: A) => B): Option.Option<Record<K, A | B>>A) => function (type parameter) B in <K extends string | symbol, A, B>(self: ReadonlyRecord<K, A>, key: NoInfer<K>, f: (a: A) => B): Option.Option<Record<K, A | B>>B
): import OptionOption.type Option.Option = /*unresolved*/ anyOption<type Record<K extends keyof any, T> = {
[P in K]: T
}
Construct a type with a set of properties K of type T
Record<function (type parameter) K in <K extends string | symbol, A, B>(self: ReadonlyRecord<K, A>, key: NoInfer<K>, f: (a: A) => B): Option.Option<Record<K, A | B>>K, function (type parameter) A in <K extends string | symbol, A, B>(self: ReadonlyRecord<K, A>, key: NoInfer<K>, f: (a: A) => B): Option.Option<Record<K, A | B>>A | function (type parameter) B in <K extends string | symbol, A, B>(self: ReadonlyRecord<K, A>, key: NoInfer<K>, f: (a: A) => B): Option.Option<Record<K, A | B>>B>> => {
if (!const has: {
<K extends string | symbol>(key: NoInfer<K>): <
A
>(
self: ReadonlyRecord<K, A>
) => boolean
<K extends string | symbol, A>(
self: ReadonlyRecord<K, A>,
key: NoInfer<K>
): boolean
}
self: ReadonlyRecord<K, A>self, key: NoInfer<K>key)) return import OptionOption.none()
return import OptionOption.some({ ...self: ReadonlyRecord<K, A>self, [key: NoInfer<K>key]: f: (a: A) => Bf(self: ReadonlyRecord<K, A>self[key: NoInfer<K>key]) })
}
)Referenced by 1 symbols