<A>(equivalence: Equivalence<A>): {
<K extends string>(that: ReadonlyRecord<K, A>): (
self: ReadonlyRecord<K, A>
) => boolean
<K extends string>(
self: ReadonlyRecord<K, A>,
that: ReadonlyRecord<K, A>
): boolean
}Checks whether all the keys and values in one record are also found in another record. Uses the provided equivalence function to compare values.
Example (Checking subrecords with a custom equivalence)
import { Equivalence, Record } from "effect"
const isSubrecord = Record.isSubrecordBy(
Equivalence.make<string>((self, that) => self.toLowerCase() === that.toLowerCase())
)
const required: Record.ReadonlyRecord<string, string> = { role: "Admin" }
const available: Record.ReadonlyRecord<string, string> = {
role: "admin",
status: "active"
}
console.log(
isSubrecord(required, available)
) // true
console.log(
isSubrecord({ role: "Admin", status: "inactive" }, available)
) // false
console.log(
isSubrecord(required, { role: "editor", status: "active" })
) // falseexport const const isSubrecordBy: <A>(
equivalence: Equivalence<A>
) => {
<K extends string>(
that: ReadonlyRecord<K, A>
): (self: ReadonlyRecord<K, A>) => boolean
<K extends string>(
self: ReadonlyRecord<K, A>,
that: ReadonlyRecord<K, A>
): boolean
}
Checks whether all the keys and values in one record are also found in another record.
Uses the provided equivalence function to compare values.
Example (Checking subrecords with a custom equivalence)
import { Equivalence, Record } from "effect"
const isSubrecord = Record.isSubrecordBy(
Equivalence.make<string>((self, that) => self.toLowerCase() === that.toLowerCase())
)
const required: Record.ReadonlyRecord<string, string> = { role: "Admin" }
const available: Record.ReadonlyRecord<string, string> = {
role: "admin",
status: "active"
}
console.log(
isSubrecord(required, available)
) // true
console.log(
isSubrecord({ role: "Admin", status: "inactive" }, available)
) // false
console.log(
isSubrecord(required, { role: "editor", status: "active" })
) // false
isSubrecordBy = <function (type parameter) A in <A>(equivalence: Equivalence<A>): {
<K extends string>(that: ReadonlyRecord<K, A>): (self: ReadonlyRecord<K, A>) => boolean;
<K extends string>(self: ReadonlyRecord<K, A>, that: ReadonlyRecord<K, A>): boolean;
}
equivalence: Equivalence<A>equivalence: type Equivalence<in A> = (self: A, that: A) => booleanRepresents an equivalence relation over type A.
When to use
Use as a type annotation when you accept or return an equivalence function.
Details
- Returns
boolean: true if values are equivalent, false otherwise
- Must satisfy reflexive, symmetric, and transitive properties
Example (Defining simple number equivalence)
import type { Equivalence } from "effect"
const numberEq: Equivalence.Equivalence<number> = (a, b) => a === b
console.log(numberEq(1, 1)) // true
console.log(numberEq(1, 2)) // false
Example (Defining custom object equivalence)
import type { Equivalence } from "effect"
interface Point {
x: number
y: number
}
const pointEq: Equivalence.Equivalence<Point> = (a, b) =>
a.x === b.x && a.y === b.y
console.log(pointEq({ x: 1, y: 2 }, { x: 1, y: 2 })) // true
Equivalence<function (type parameter) A in <A>(equivalence: Equivalence<A>): {
<K extends string>(that: ReadonlyRecord<K, A>): (self: ReadonlyRecord<K, A>) => boolean;
<K extends string>(self: ReadonlyRecord<K, A>, that: ReadonlyRecord<K, A>): boolean;
}
function (type parameter) K in <K extends string>(that: ReadonlyRecord<K, A>): (self: ReadonlyRecord<K, A>) => booleanK extends string>(that: ReadonlyRecord<K, A>that: 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>(that: ReadonlyRecord<K, A>): (self: ReadonlyRecord<K, A>) => booleanK, function (type parameter) A in <A>(equivalence: Equivalence<A>): {
<K extends string>(that: ReadonlyRecord<K, A>): (self: ReadonlyRecord<K, A>) => boolean;
<K extends string>(self: ReadonlyRecord<K, A>, that: ReadonlyRecord<K, A>): boolean;
}
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>(that: ReadonlyRecord<K, A>): (self: ReadonlyRecord<K, A>) => booleanK, function (type parameter) A in <A>(equivalence: Equivalence<A>): {
<K extends string>(that: ReadonlyRecord<K, A>): (self: ReadonlyRecord<K, A>) => boolean;
<K extends string>(self: ReadonlyRecord<K, A>, that: ReadonlyRecord<K, A>): boolean;
}
function (type parameter) K in <K extends string>(self: ReadonlyRecord<K, A>, that: ReadonlyRecord<K, A>): booleanK extends string>(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>(self: ReadonlyRecord<K, A>, that: ReadonlyRecord<K, A>): booleanK, function (type parameter) A in <A>(equivalence: Equivalence<A>): {
<K extends string>(that: ReadonlyRecord<K, A>): (self: ReadonlyRecord<K, A>) => boolean;
<K extends string>(self: ReadonlyRecord<K, A>, that: ReadonlyRecord<K, A>): boolean;
}
that: ReadonlyRecord<K, A>that: 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>(self: ReadonlyRecord<K, A>, that: ReadonlyRecord<K, A>): booleanK, function (type parameter) A in <A>(equivalence: Equivalence<A>): {
<K extends string>(that: ReadonlyRecord<K, A>): (self: ReadonlyRecord<K, A>) => boolean;
<K extends string>(self: ReadonlyRecord<K, A>, that: ReadonlyRecord<K, A>): boolean;
}
dual<(...args: Array<any>) => any, <K extends string>(self: ReadonlyRecord<K, A>, that: ReadonlyRecord<K, A>) => boolean>(arity: 2, body: <K extends string>(self: ReadonlyRecord<K, A>, that: ReadonlyRecord<K, A>) => boolean): ((...args: Array<any>) => any) & (<K extends string>(self: ReadonlyRecord<K, A>, that: ReadonlyRecord<K, A>) => boolean) (+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(2, <function (type parameter) K in <K extends string>(self: ReadonlyRecord<K, A>, that: ReadonlyRecord<K, A>): booleanK extends string>(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>(self: ReadonlyRecord<K, A>, that: ReadonlyRecord<K, A>): booleanK, function (type parameter) A in <A>(equivalence: Equivalence<A>): {
<K extends string>(that: ReadonlyRecord<K, A>): (self: ReadonlyRecord<K, A>) => boolean;
<K extends string>(self: ReadonlyRecord<K, A>, that: ReadonlyRecord<K, A>): boolean;
}
that: ReadonlyRecord<K, A>that: 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>(self: ReadonlyRecord<K, A>, that: ReadonlyRecord<K, A>): booleanK, function (type parameter) A in <A>(equivalence: Equivalence<A>): {
<K extends string>(that: ReadonlyRecord<K, A>): (self: ReadonlyRecord<K, A>) => boolean;
<K extends string>(self: ReadonlyRecord<K, A>, that: ReadonlyRecord<K, A>): boolean;
}
const key: K extends stringkey of 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, A>self)) {
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
}
that: ReadonlyRecord<K, A>that, const key: K extends stringkey) || !equivalence: Equivalence<A>equivalence(self: ReadonlyRecord<K, A>self[const key: K extends stringkey], that: ReadonlyRecord<K, A>that[const key: K extends stringkey])) {
return false
}
}
return true
})