effect-io-ai

Package: effect
Module: Struct

Struct.mapPick

Applies a Lambda transformation only to the specified keys; all other keys are copied unchanged.

When to use

Use when you want to apply the same transformation to a subset of properties.

Example (Wrapping only selected values in arrays)

import { pipe, Struct } from "effect"

interface AsArray extends Struct.Lambda {
  <A>(self: A): Array<A>
  readonly "~lambda.out": Array<this["~lambda.in"]>
}

const asArray = Struct.lambda<AsArray>((a) => [a])
const result = pipe(
  { x: 1, y: 2, z: 3 },
  Struct.mapPick(["x", "z"], asArray)
)
console.log(result) // { x: [1], y: 2, z: [3] }

See

• map – apply a lambda to all keys
• mapOmit – apply a lambda to all keys except selected ones

Signature

declare const mapPick: { <S extends object, const Keys extends ReadonlyArray<keyof S>, L extends Lambda>(keys: Keys, lambda: L): (self: S) => { [K in keyof S]: K extends Keys[number] ? Apply<L, S[K]> : S[K]; }; <S extends object, const Keys extends ReadonlyArray<keyof S>, L extends Lambda>(self: S, keys: Keys, lambda: L): { [K in keyof S]: K extends Keys[number] ? Apply<L, S[K]> : S[K]; }; }

Source

Since v4.0.0