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Struct overview

This module provides utility functions for working with structs in TypeScript.

Added in v1.0.0

Table of contents

combinators

getEquivalence

Given a struct of Equivalences returns a new Equivalence that compares values of a struct by applying each Equivalence to the corresponding property of the struct.

Alias of {@link Equivalence.struct}.

Signature

export declare const getEquivalence: <R extends Record<string, Equivalence.Equivalence<any>>>(
  isEquivalents: R
) => Equivalence.Equivalence<{ readonly [K in keyof R]: [R[K]] extends [Equivalence.Equivalence<infer A>] ? A : never }>

Example

import { getEquivalence } from '@effect/data/Struct'
import * as S from '@effect/data/String'
import * as N from '@effect/data/Number'

const PersonEquivalence = getEquivalence({
  name: S.Equivalence,
  age: N.Equivalence,
})

assert.deepStrictEqual(PersonEquivalence({ name: 'John', age: 25 }, { name: 'John', age: 25 }), true)
assert.deepStrictEqual(PersonEquivalence({ name: 'John', age: 25 }, { name: 'John', age: 40 }), false)

Added in v1.0.0

getOrder

This function creates and returns a new Order for a struct of values based on the given Orders for each property in the struct.

Alias of {@link order.struct}.

Signature

export declare const getOrder: <R extends { readonly [x: string]: order.Order<any> }>(
  fields: R
) => order.Order<{ [K in keyof R]: [R[K]] extends [order.Order<infer A>] ? A : never }>

Added in v1.0.0

utils

evolve

Transforms the values of a Struct provided a transformation function for each key. If no transformation function is provided for a key, it will return the origional value for that key.

Signature

export declare const evolve: {
  <O, T extends Partial<{ [K in keyof O]: (a: O[K]) => unknown }>>(t: T): (obj: O) => {
    [K in keyof O]: K extends keyof T ? (T[K] extends (...a: any) => any ? ReturnType<T[K]> : O[K]) : O[K]
  }
  <O, T extends Partial<{ [K in keyof O]: (a: O[K]) => unknown }>>(obj: O, t: T): {
    [K in keyof O]: K extends keyof T ? (T[K] extends (...a: any) => any ? ReturnType<T[K]> : O[K]) : O[K]
  }
}

Example

import { evolve } from '@effect/data/Struct'
import { pipe } from '@effect/data/Function'

assert.deepStrictEqual(
  pipe(
    { a: 'a', b: 1, c: 3 },
    evolve({
      a: (a) => a.length,
      b: (b) => b * 2,
    })
  ),
  { a: 1, b: 2, c: 3 }
)

Added in v1.0.0

omit

Create a new object by omitting properties of an existing object.

Signature

export declare const omit: <S, Keys extends readonly [keyof S, ...(keyof S)[]]>(
  ...keys: Keys
) => (s: S) => { [K in Exclude<keyof S, Keys[number]>]: S[K] }

Example

import { omit } from '@effect/data/Struct'
import { pipe } from '@effect/data/Function'

assert.deepStrictEqual(pipe({ a: 'a', b: 1, c: true }, omit('c')), { a: 'a', b: 1 })

Added in v1.0.0

pick

Create a new object by picking properties of an existing object.

Signature

export declare const pick: <S, Keys extends readonly [keyof S, ...(keyof S)[]]>(
  ...keys: Keys
) => (s: S) => { [K in Keys[number]]: S[K] }

Example

import { pick } from '@effect/data/Struct'
import { pipe } from '@effect/data/Function'

assert.deepStrictEqual(pipe({ a: 'a', b: 1, c: true }, pick('a', 'b')), { a: 'a', b: 1 })

Added in v1.0.0