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Types overview

A collection of types that are commonly used types.

Added in v1.0.0

Table of contents

models

Equals (type alias)

Determines if two types are equal.

Signature

export type Equals<X, Y> = (<T>() => T extends X ? 1 : 2) extends <T>() => T extends Y ? 1 : 2 ? true : false

Example

import * as Types from '@effect/data/Types'

type Res1 = Types.Equals<{ a: number }, { a: number }> // true
type Res2 = Types.Equals<{ a: number }, { b: number }> // false

Added in v1.0.0

MergeLeft (type alias)

Merges two object where the keys of the left object take precedence in the case of a conflict.

Signature

export type MergeLeft<K, H> = Simplify<{
  [k in keyof K | keyof H]: k extends keyof K ? K[k] : k extends keyof H ? H[k] : never
}>

Example

import * as Types from '@effect/data/Types'
type MergeLeft = Types.MergeLeft<{ a: number; b: number }, { a: string }> // { a: number; b: number; }

Added in v1.0.0

MergeRight (type alias)

Merges two object where the keys of the right object take precedence in the case of a conflict.

Signature

export type MergeRight<K, H> = Simplify<{
  [k in keyof K | keyof H]: k extends keyof H ? H[k] : k extends keyof K ? K[k] : never
}>

Example

import * as Types from '@effect/data/Types'
type MergeRight = Types.MergeRight<{ a: number; b: number }, { a: string }> // { a: string; b: number; }

Added in v1.0.0

types

ExcludeTag (type alias)

Excludes the tagged object from the type.

Signature

export type ExcludeTag<E, K extends Tags<E>> = Exclude<E, { _tag: K }>

Example

import * as Types from '@effect/data/Types'

type Res = Types.ExcludeTag<string | { _tag: 'a' } | { _tag: 'b' }, 'a'> // string | { _tag: "b" }

Added in v1.0.0

ExtractTag (type alias)

Extracts the type of the given tag.

Signature

export type ExtractTag<E, K extends Tags<E>> = Extract<E, { _tag: K }>

Example

import * as Types from '@effect/data/Types'

type Res = Types.ExtractTag<{ _tag: 'a'; a: number } | { _tag: 'b'; b: number }, 'b'> // { _tag: "b", b: number }

Added in v1.0.0

Simplify (type alias)

Simplifies the type signature of a type.

Signature

export type Simplify<A> = {
  [K in keyof A]: A[K]
} extends infer B
  ? B
  : never

Example

import * as Types from '@effect/data/Types'

type Res = Types.Simplify<{ a: number } & { b: number }> // { a: number; b: number; }

Added in v1.0.0

Tags (type alias)

Returns the tags in a type.

Signature

export type Tags<E> = E extends { _tag: string } ? E['_tag'] : never

Example

import * as Types from '@effect/data/Types'

type Res = Types.Tags<string | { _tag: 'a' } | { _tag: 'b' }> // "a" | "b"

Added in v1.0.0

UnionToIntersection (type alias)

A utility type that transforms a union type T into an intersection type.

Signature

export type UnionToIntersection<T> = (T extends any ? (x: T) => any : never) extends (x: infer R) => any ? R : never

Added in v1.0.0