effect-io-ai

Package: effect
Module: Option

Option.makeReducer

Creates a Reducer for Option<A> that prioritizes the first non-None value and combines values when both are Some.

When to use

Use to build an Option reducer that falls back to the first available value when either side may be absent.

Details

• None + None → None
• Some(a) + None → Some(a)
• None + Some(b) → Some(b)
• Some(a) + Some(b) → Some(combine(a, b))
• Initial value is None

Example (Reducing with first-wins semantics)

import { Number, Option } from "effect"

const reducer = Option.makeReducer(Number.ReducerSum)
console.log(reducer.combineAll([Option.some(1), Option.none(), Option.some(2)]))
// Output: { _id: 'Option', _tag: 'Some', value: 3 }

See

• makeReducerFailFast for fail-fast semantics

Signature

declare const makeReducer: <A>(combiner: Combiner.Combiner<A>) => Reducer.Reducer<Option<A>>

Source

Since v4.0.0