effect-io-ai

Package: effect
Module: Optic

Optic.makeLens

Creates a Lens from a getter and a replacer.

When to use

Use when you can always extract A from S and produce a new S by substituting a new A.

Details

• replace(a, s) should return a structurally new S with a in place of the old focus.

Example (Focusing on the first element of a pair)

import { Optic } from "effect"

const _first = Optic.makeLens<readonly [string, number], string>(
  (pair) => pair[0],
  (s, pair) => [s, pair[1]]
)

console.log(_first.get(["hello", 42]))
// Output: "hello"

console.log(_first.replace("world", ["hello", 42]))
// Output: ["world", 42]

See

• Lens — the type this function returns
• makeIso — when no original S is needed for set

Signature

declare const makeLens: <S, A>(get: (s: S) => A, replace: (a: A, s: S) => S) => Lens<S, A>

Source

Since v4.0.0