How does mori compare to Immutable.js in terms of performance?

Mori is often faster, especially for small hash maps, due to ClojureScript's optimized data structures and continuous benchmarking. However, it has a larger bundle size, so the choice depends on balancing speed and file size for your project.

How to use mori with React for immutable state management?

Integrate mori by storing React state in its data structures like vectors or maps, and update them non-destructively using functional APIs. For example, use mori.conj to add items without mutating the original state.

What are the breaking changes in mori 0.3.0?

Version 0.3.0 introduced idiomatic JavaScript naming conventions, changing the API from previous versions. Developers upgrading need to update their code to match the new naming, as noted in the README's breaking changes section.

Does mori work with TypeScript?

Mori is compiled JavaScript, so it can be used with TypeScript, but official type definitions might not be provided. Developers often rely on community typings or create custom ones for type safety.

How to convert a JavaScript array to a mori vector efficiently?

Use mori.into(mori.vector(), array) to leverage structural sharing, or for mutable building, use mori._thaw and mori._freeze operations for performance-critical scenarios, as shown in the examples.

Can mori transducers replace JavaScript array methods?

Yes, mori transducers offer zero-allocation transformations that can outperform chained array methods like map and filter, especially for large datasets, by avoiding intermediate allocations, as demonstrated in performance tests.

Open-Awesome

mori

Clojure

A JavaScript library providing ClojureScript's persistent data structures and functional APIs for immutable data manipulation.

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3.4k stars142 forks0 contributors

What is mori?

Mori is a JavaScript library that provides ClojureScript's persistent data structures and supporting functional APIs for vanilla JavaScript. It solves the problem of efficient immutable data manipulation by offering structures like vectors, maps, and sets with non-destructive updates, enabling predictable state management in applications.

Target Audience

JavaScript developers building applications that require immutable data structures, such as state management in UIs, functional programming projects, or performance-sensitive data processing tasks.

Value Proposition

Developers choose Mori for its battle-tested ClojureScript data structures, which have been optimized over years of real-world use, and its purely functional API that avoids side effects. It offers performance advantages, especially with small-sized maps, and includes advanced features like transducers and ES6 compatibility.

Overview

ClojureScript's persistent data structures and supporting API from the comfort of vanilla JavaScript

Use Cases

Best For

Implementing immutable state management in JavaScript applications
Functional programming in JavaScript with persistent data structures
High-performance data transformations using transducers
Building applications that require efficient non-destructive updates
Migrating from ClojureScript to JavaScript while retaining data structure semantics
Benchmarking against other immutable data structure libraries like Immutable.js

Not Ideal For

Applications with strict bundle size constraints, such as progressive web apps targeting slow networks
Teams accustomed to object-oriented APIs or method chaining patterns
Projects that rely heavily on mutable data structures for legacy code integration without refactoring
Environments targeting older browsers without ES6 Symbol.iterator support

Pros & Cons

Pros

Battle-Tested Performance

Based on ClojureScript's data structures optimized over years, with benchmarks showing faster performance than Immutable.js for small hash maps, as noted in the README.

Functional Purity

Uses a purely functional API with no public methods on data structures, promoting immutability and side-effect-free code, which is central to its design philosophy.

Advanced Features

Includes transducers for zero-allocation data transformations and lazy sequences, enabling high-performance pipelines and efficient on-demand computation.

ES6 Compatibility

Supports ES6 iteration via Symbol.iterator and interfaces similar to proposed Map/Set, ensuring seamless integration with modern JavaScript ecosystems.

Cons

Larger Bundle Size

Gzipped base module is about 6K larger than Immutable.js, which can negatively impact load times in performance-sensitive web applications.

Steep Learning Curve

Requires familiarity with ClojureScript's functional paradigms and APIs, which may be alien to developers used to imperative or object-oriented JavaScript.

Complex Build Setup

Building from source necessitates Java SDK and Leiningen, adding overhead compared to pure npm-based JavaScript libraries, as outlined in the build instructions.

Open Source Alternative To

mori is an open-source alternative to the following products:

immutable.js

Immutable.js is a JavaScript library providing persistent immutable data structures, such as Lists and Maps, for functional programming and state management.

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