@context-action/mutative-core

The Context-Action maintained core implementation of Mutative. It preserves the upstream Mutative API while carrying the maintained fork fixes from mineclover/mutative, including lazy array drafts, nested create() isolation, and the produce alias.

Installation

pnpm add @context-action/mutative-core

Usage

import { produce } from '@context-action/mutative-core';

const next = produce({ count: 0 }, (draft) => {
  draft.count += 1;
});

Core contracts

• Drafts support plain objects, arrays, Map, and Set. Unchanged branches retain their original references through copy-on-write finalization.
• Pass enablePatches: true to receive [nextState, patches, inversePatches]. Set changes are represented as a replace patch so inverse replay preserves insertion order.
• The default patch path is an array. A string JSON Pointer path can only represent string Map keys and string properties; using pathAsArray: false with numeric/object Map keys or Symbol properties throws. Use array paths for those keys.
• strict: true rejects non-draft replacement values. Use rawReturn(value) when an intentional raw replacement is required. unsafe(callback) is the scoped escape hatch for accessing mutable values in strict mode.
• enableAutoFreeze: true freezes object, array, Map, and Set shells and blocks their normal mutators. As required by JavaScript collection semantics, a direct Map.prototype.set.call(map, ...)/Set.prototype.add.call(...) can still bypass an instance-level guard.

@context-action/mutative is the higher-level Context-Action adapter with patch helpers and time-travel controls. Most application code should use the adapter; use this package when the upstream-compatible immutable update API is needed directly.

Lineage and license

This package contains the MIT-licensed Mutative implementation maintained by the Context-Action project. See LICENSE and the fork changelog for the upstream issue and pull-request work carried forward.

The original project is unadlib/mutative; the maintained source fork is mineclover/mutative. The exact imported revision is recorded in UPSTREAM.md.