effect-io-ai

Package: effect
Module: HashMap

HashMap.HashMap.UpdateFn

A function that updates a value based on its current state. Takes an Option representing the current value and returns an Option representing the new value.

Example (Updating values from Options)

import { HashMap, Option } from "effect"

const map = HashMap.make(["a", 1], ["b", 2])

// Increment existing value or set to 1 if not present
const updateFn = (option: Option.Option<number>) =>
  Option.isSome(option) ? Option.some(option.value + 1) : Option.some(1)

const updated = HashMap.modifyAt(map, "a", updateFn)
console.log(HashMap.get(updated, "a")) // Option.some(2)

Signature

type UpdateFn<V> = (option: Option<V>) => Option<V>

Source

Since v2.0.0