# getify/monio

The most powerful IO monad implementation in JS, possibly in any language!

Repository: https://github.com/getify/monio
Canonical: https://ross.abutalabs.com/products/monio
Language: JavaScript
License: MIT
License Family: permissive
Topics: javascript, js, fp, functional-programming, monad, monads, io, maybe, either, observable
Last push: 2026-05-01T21:23:16+00:00

## Health v2 (maintenance only)
Score: 68/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 80, release rhythm 35, longevity 100
- inputs: {"age_days": 2294, "days_push": 124, "days_rel": null, "gap_med": null, "n_releases_24m": 0}
- flags: no_releases
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 1124, forks 61 (observed 2026-08-28T04:03:40.683359+00:00)

## What it is
Monio is a JavaScript library providing an async-capable IO monad (including 'do' style) along with companion monads like Maybe, Either, and observable variants. It aims to bring powerful functional programming abstractions to JS with a rich, well-documented implementation.

## Use cases
- handle side effects functionally in JavaScript with an IO monad
- compose async operations without promise chaining
- use Maybe and Either monads for null and error handling
- write do-notation style functional code in JS
- learn functional programming and monads in JavaScript
- manage observable/reactive streams with monadic composition

## When to choose
- you want a mature, feature-rich IO monad implementation for JavaScript
- you're doing functional programming in JS and need Maybe/Either/IO monads
- you need async-aware monadic composition with do-style syntax
- you want a library with extensive documentation and tutorials on monads

## When to avoid
- your team is unfamiliar with functional programming concepts
- you need a minimal zero-dependency utility rather than a full FP toolkit
- you're working in a non-JavaScript environment

## Facets
- artifact type: library
- maturity: active
- function: serialization, concurrency, developer-tools
- domain: developer-tools, programming-languages
- platform: cross-platform
- tags: functional-programming, monads, io-monad, maybe, either, async, observable, esm, algorithms, nodejs, javascript

## Member repositories
- getify/monio (main) score 68

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:03:40.683359+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-30T06:39:38.846209+00:00, confidence not recorded.
  - readme: https://github.com/getify/monio (fetched 2026-08-28T04:03:40.683359+00:00, sha 61cda975ca4a)
  - registry_npm: https://registry.npmjs.org/monio (fetched 2026-08-29T12:44:02.276020+00:00, sha f22b3858590e)
- Data as of 2026-08-30T08:39:29.467469+00:00.