<K extends string | symbol, K1 extends K | ((string | symbol) & {}), B>(
key: K1,
value: B
): <A>(self: ReadonlyRecord<K, A>) => Record<K | K1, A | B>
<
K extends string | symbol,
A,
K1 extends K | ((string | symbol) & {}),
B
>(
self: ReadonlyRecord<K, A>,
key: K1,
value: B
): Record<K | K1, A | B>Adds a new key-value pair or update an existing key's value in a record.
Example (Setting a record value)
import { Record } from "effect"
import * as assert from "node:assert"
assert.deepStrictEqual(Record.set("a", 5)({ a: 1, b: 2 }), { a: 5, b: 2 })
assert.deepStrictEqual(Record.set("c", 5)({ a: 1, b: 2 }), { a: 1, b: 2, c: 5 })mutations
Source effect/Record.ts:104020 lines
export const const set: {
<
K extends string | symbol,
K1 extends K | ((string | symbol) & {}),
B
>(
key: K1,
value: B
): <A>(
self: ReadonlyRecord<K, A>
) => Record<K | K1, A | B>
<
K extends string | symbol,
A,
K1 extends K | ((string | symbol) & {}),
B
>(
self: ReadonlyRecord<K, A>,
key: K1,
value: B
): Record<K | K1, A | B>
}
Adds a new key-value pair or update an existing key's value in a record.
Example (Setting a record value)
import { Record } from "effect"
import * as assert from "node:assert"
assert.deepStrictEqual(Record.set("a", 5)({ a: 1, b: 2 }), { a: 5, b: 2 })
assert.deepStrictEqual(Record.set("c", 5)({ a: 1, b: 2 }), { a: 1, b: 2, c: 5 })
set: {
<function (type parameter) K in <K extends string | symbol, K1 extends K | ((string | symbol) & {}), B>(key: K1, value: B): <A>(self: ReadonlyRecord<K, A>) => Record<K | K1, A | B>K extends string | symbol, function (type parameter) K1 in <K extends string | symbol, K1 extends K | ((string | symbol) & {}), B>(key: K1, value: B): <A>(self: ReadonlyRecord<K, A>) => Record<K | K1, A | B>K1 extends function (type parameter) K in <K extends string | symbol, K1 extends K | ((string | symbol) & {}), B>(key: K1, value: B): <A>(self: ReadonlyRecord<K, A>) => Record<K | K1, A | B>K | ((string | symbol) & {}), function (type parameter) B in <K extends string | symbol, K1 extends K | ((string | symbol) & {}), B>(key: K1, value: B): <A>(self: ReadonlyRecord<K, A>) => Record<K | K1, A | B>B>(
key: K1 extends K | ((string | symbol) & {})key: function (type parameter) K1 in <K extends string | symbol, K1 extends K | ((string | symbol) & {}), B>(key: K1, value: B): <A>(self: ReadonlyRecord<K, A>) => Record<K | K1, A | B>K1,
value: Bvalue: function (type parameter) B in <K extends string | symbol, K1 extends K | ((string | symbol) & {}), B>(key: K1, value: B): <A>(self: ReadonlyRecord<K, A>) => Record<K | K1, A | B>B
): <function (type parameter) A in <A>(self: ReadonlyRecord<K, A>): Record<K | K1, A | B>A>(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, K1 extends K | ((string | symbol) & {}), B>(key: K1, value: B): <A>(self: ReadonlyRecord<K, A>) => Record<K | K1, A | B>K, function (type parameter) A in <A>(self: ReadonlyRecord<K, A>): Record<K | K1, A | B>A>) => 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, K1 extends K | ((string | symbol) & {}), B>(key: K1, value: B): <A>(self: ReadonlyRecord<K, A>) => Record<K | K1, A | B>K | function (type parameter) K1 in <K extends string | symbol, K1 extends K | ((string | symbol) & {}), B>(key: K1, value: B): <A>(self: ReadonlyRecord<K, A>) => Record<K | K1, A | B>K1, function (type parameter) A in <A>(self: ReadonlyRecord<K, A>): Record<K | K1, A | B>A | function (type parameter) B in <K extends string | symbol, K1 extends K | ((string | symbol) & {}), B>(key: K1, value: B): <A>(self: ReadonlyRecord<K, A>) => Record<K | K1, A | B>B>
<function (type parameter) K in <K extends string | symbol, A, K1 extends K | ((string | symbol) & {}), B>(self: ReadonlyRecord<K, A>, key: K1, value: B): Record<K | K1, A | B>K extends string | symbol, function (type parameter) A in <K extends string | symbol, A, K1 extends K | ((string | symbol) & {}), B>(self: ReadonlyRecord<K, A>, key: K1, value: B): Record<K | K1, A | B>A, function (type parameter) K1 in <K extends string | symbol, A, K1 extends K | ((string | symbol) & {}), B>(self: ReadonlyRecord<K, A>, key: K1, value: B): Record<K | K1, A | B>K1 extends function (type parameter) K in <K extends string | symbol, A, K1 extends K | ((string | symbol) & {}), B>(self: ReadonlyRecord<K, A>, key: K1, value: B): Record<K | K1, A | B>K | ((string | symbol) & {}), function (type parameter) B in <K extends string | symbol, A, K1 extends K | ((string | symbol) & {}), B>(self: ReadonlyRecord<K, A>, key: K1, value: B): Record<K | K1, 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, K1 extends K | ((string | symbol) & {}), B>(self: ReadonlyRecord<K, A>, key: K1, value: B): Record<K | K1, A | B>K, function (type parameter) A in <K extends string | symbol, A, K1 extends K | ((string | symbol) & {}), B>(self: ReadonlyRecord<K, A>, key: K1, value: B): Record<K | K1, A | B>A>,
key: K1 extends K | ((string | symbol) & {})key: function (type parameter) K1 in <K extends string | symbol, A, K1 extends K | ((string | symbol) & {}), B>(self: ReadonlyRecord<K, A>, key: K1, value: B): Record<K | K1, A | B>K1,
value: Bvalue: function (type parameter) B in <K extends string | symbol, A, K1 extends K | ((string | symbol) & {}), B>(self: ReadonlyRecord<K, A>, key: K1, value: B): Record<K | K1, A | B>B
): 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, K1 extends K | ((string | symbol) & {}), B>(self: ReadonlyRecord<K, A>, key: K1, value: B): Record<K | K1, A | B>K | function (type parameter) K1 in <K extends string | symbol, A, K1 extends K | ((string | symbol) & {}), B>(self: ReadonlyRecord<K, A>, key: K1, value: B): Record<K | K1, A | B>K1, function (type parameter) A in <K extends string | symbol, A, K1 extends K | ((string | symbol) & {}), B>(self: ReadonlyRecord<K, A>, key: K1, value: B): Record<K | K1, A | B>A | function (type parameter) B in <K extends string | symbol, A, K1 extends K | ((string | symbol) & {}), B>(self: ReadonlyRecord<K, A>, key: K1, value: B): Record<K | K1, A | B>B>
} = dual<(...args: Array<any>) => any, <K extends string | symbol, A, K1 extends K | ((string | symbol) & {}), B>(self: ReadonlyRecord<K, A>, key: K1, value: B) => Record<K | K1, A | B>>(arity: 3, body: <K extends string | symbol, A, K1 extends K | ((string | symbol) & {}), B>(self: ReadonlyRecord<K, A>, key: K1, value: B) => Record<K | K1, A | B>): ((...args: Array<any>) => any) & (<K extends string | symbol, A, K1 extends K | ((string | symbol) & {}), B>(self: ReadonlyRecord<K, A>, key: K1, value: B) => Record<K | K1, A | B>) (+1 overload)Creates a function that can be called in data-first style or data-last
(pipe-friendly) style.
When to use
Use to expose one implementation through both direct and pipe-friendly
call styles.
Details
Pass either the arity of the uncurried function or a predicate that decides
whether the current call is data-first. Arity is the common case. Use a
predicate when optional arguments make arity ambiguous.
Example (Selecting data-first or data-last style by arity)
import { Function, pipe } from "effect"
const sum = Function.dual<
(that: number) => (self: number) => number,
(self: number, that: number) => number
>(2, (self, that) => self + that)
console.log(sum(2, 3)) // 5
console.log(pipe(2, sum(3))) // 5
Example (Defining overloads with call signatures)
import { Function, pipe } from "effect"
const sum: {
(that: number): (self: number) => number
(self: number, that: number): number
} = Function.dual(2, (self: number, that: number): number => self + that)
console.log(sum(2, 3)) // 5
console.log(pipe(2, sum(3))) // 5
Example (Selecting data-first or data-last style with a predicate)
import { Function, pipe } from "effect"
const sum = Function.dual<
(that: number) => (self: number) => number,
(self: number, that: number) => number
>(
(args) => args.length === 2,
(self, that) => self + that
)
console.log(sum(2, 3)) // 5
console.log(pipe(2, sum(3))) // 5
dual(
3,
<function (type parameter) K in <K extends string | symbol, A, K1 extends K | ((string | symbol) & {}), B>(self: ReadonlyRecord<K, A>, key: K1, value: B): Record<K | K1, A | B>K extends string | symbol, function (type parameter) A in <K extends string | symbol, A, K1 extends K | ((string | symbol) & {}), B>(self: ReadonlyRecord<K, A>, key: K1, value: B): Record<K | K1, A | B>A, function (type parameter) K1 in <K extends string | symbol, A, K1 extends K | ((string | symbol) & {}), B>(self: ReadonlyRecord<K, A>, key: K1, value: B): Record<K | K1, A | B>K1 extends function (type parameter) K in <K extends string | symbol, A, K1 extends K | ((string | symbol) & {}), B>(self: ReadonlyRecord<K, A>, key: K1, value: B): Record<K | K1, A | B>K | ((string | symbol) & {}), function (type parameter) B in <K extends string | symbol, A, K1 extends K | ((string | symbol) & {}), B>(self: ReadonlyRecord<K, A>, key: K1, value: B): Record<K | K1, 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, K1 extends K | ((string | symbol) & {}), B>(self: ReadonlyRecord<K, A>, key: K1, value: B): Record<K | K1, A | B>K, function (type parameter) A in <K extends string | symbol, A, K1 extends K | ((string | symbol) & {}), B>(self: ReadonlyRecord<K, A>, key: K1, value: B): Record<K | K1, A | B>A>,
key: K1 extends K | ((string | symbol) & {})key: function (type parameter) K1 in <K extends string | symbol, A, K1 extends K | ((string | symbol) & {}), B>(self: ReadonlyRecord<K, A>, key: K1, value: B): Record<K | K1, A | B>K1,
value: Bvalue: function (type parameter) B in <K extends string | symbol, A, K1 extends K | ((string | symbol) & {}), B>(self: ReadonlyRecord<K, A>, key: K1, value: B): Record<K | K1, A | B>B
): 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, K1 extends K | ((string | symbol) & {}), B>(self: ReadonlyRecord<K, A>, key: K1, value: B): Record<K | K1, A | B>K | function (type parameter) K1 in <K extends string | symbol, A, K1 extends K | ((string | symbol) & {}), B>(self: ReadonlyRecord<K, A>, key: K1, value: B): Record<K | K1, A | B>K1, function (type parameter) A in <K extends string | symbol, A, K1 extends K | ((string | symbol) & {}), B>(self: ReadonlyRecord<K, A>, key: K1, value: B): Record<K | K1, A | B>A | function (type parameter) B in <K extends string | symbol, A, K1 extends K | ((string | symbol) & {}), B>(self: ReadonlyRecord<K, A>, key: K1, value: B): Record<K | K1, A | B>B> => {
return { ...self: ReadonlyRecord<K, A>self, [key: K1 extends K | ((string | symbol) & {})key]: value: Bvalue } as any
}
)