# OCaml

> OCaml is a general-purpose, industrial-strength programming language with an emphasis on expressiveness and safety. It is the technology of choice in companies where a single mistake can cost millions and speed matters. [ocaml.org](https://ocaml.org) is the official website for the OCaml community, providing documentation, tutorials, package search, and community resources.

## Documentation

- [Learn OCaml](https://ocaml.org/docs): Entry point to all documentation and tutorials
- [Install OCaml](https://ocaml.org/install): How to install OCaml and the OCaml Platform tools
- [Get Started](https://ocaml.org/docs/get-started): Beginner tutorials for getting up and running
- [Language](https://ocaml.org/docs/language): Tutorials on OCaml language features
- [Guides](https://ocaml.org/docs/guides): Advanced how-to guides
- [Platform Tools](https://ocaml.org/docs/tools): Tutorials on build tools, editors, and CI

## Tutorials: Getting Started

- [Installing OCaml](https://ocaml.org/docs/installing-ocaml): Install the compiler and platform tools
- [A Tour of OCaml](https://ocaml.org/docs/tour-of-ocaml): Quick overview of OCaml's key features
- [Your First Program](https://ocaml.org/docs/your-first-program): Write, compile, and run your first OCaml project
- [Set Up an Editor](https://ocaml.org/docs/set-up-editor): Configure VS Code or other editors for OCaml
- [Introduction to the Toplevel](https://ocaml.org/docs/toplevel-introduction): Use the interactive OCaml REPL
- [OCaml on Windows](https://ocaml.org/docs/ocaml-on-windows): Installing and using OCaml on Windows

## Tutorials: Language

- [Values and Functions](https://ocaml.org/docs/values-and-functions): Core concepts of OCaml values and function definitions
- [Basic Data Types](https://ocaml.org/docs/basic-data-types): Tuples, records, variants, and pattern matching
- [Loops and Recursion](https://ocaml.org/docs/loops-recursion): Iteration and recursive programming
- [Lists](https://ocaml.org/docs/lists): Working with OCaml's linked lists
- [Higher-Order Functions](https://ocaml.org/docs/higher-order-functions): Map, filter, fold, and function composition
- [Labelled and Optional Arguments](https://ocaml.org/docs/labels): Functions with labelled and optional arguments
- [Options](https://ocaml.org/docs/options): Handling optional values safely
- [Mutability and Imperative Control Flow](https://ocaml.org/docs/mutability-imperative-control-flow): Refs, mutable fields, loops
- [Modules](https://ocaml.org/docs/modules): Structuring code with modules and signatures
- [Functors](https://ocaml.org/docs/functors): Parameterised modules
- [First-Class Modules](https://ocaml.org/docs/first-class-modules): Passing modules as ordinary values
- [Error Handling](https://ocaml.org/docs/error-handling): Result types, exceptions, and best practices
- [Arrays](https://ocaml.org/docs/arrays): Fixed-size mutable arrays
- [Maps](https://ocaml.org/docs/maps): Functional key-value maps
- [Sets](https://ocaml.org/docs/sets): Functional sets
- [Hash Tables](https://ocaml.org/docs/hash-tables): Mutable hash tables
- [Sequences](https://ocaml.org/docs/sequences): Lazy sequences for efficient iteration
- [Memoization](https://ocaml.org/docs/memoization): Caching function results
- [Monads](https://ocaml.org/docs/monads): Monadic programming patterns in OCaml
- [Operators](https://ocaml.org/docs/operators): Using and defining custom operators
- [Objects](https://ocaml.org/docs/objects): OCaml's object system
- [Preprocessors and PPXs](https://ocaml.org/docs/metaprogramming): Metaprogramming with PPX rewriters
- [Memory Representation of Values](https://ocaml.org/docs/memory-representation): How OCaml values are laid out in memory
- [Garbage Collector](https://ocaml.org/docs/garbage-collector): Understanding OCaml's GC

## Tutorials: Platform

- [Bootstrapping a Dune Project](https://ocaml.org/docs/bootstrapping-a-dune-project): Create a new project with Dune
- [Managing Dependencies](https://ocaml.org/docs/managing-dependencies): Use opam to manage packages
- [Running Executables and Tests](https://ocaml.org/docs/running-executables-and-tests-with-dune): Build and test with Dune
- [Formatting Your Code](https://ocaml.org/docs/formatting-your-code): Auto-format with ocamlformat
- [Generating Documentation](https://ocaml.org/docs/generating-documentation): Generate docs with odoc

## Tutorials: Guides

- [Debugging](https://ocaml.org/docs/debugging): Debugging techniques and tools
- [Profiling](https://ocaml.org/docs/profiling): Performance profiling
- [Calling C Libraries](https://ocaml.org/docs/calling-c-libraries): FFI with C code
- [Common Errors](https://ocaml.org/docs/common-errors): Frequent mistakes and how to fix them
- [Data Structures Comparison](https://ocaml.org/docs/data-structures-comparison): Choosing the right data structure

## Language Manual and API

- [OCaml Manual](https://ocaml.org/manual/): The official OCaml compiler manual
- [Standard Library API](https://ocaml.org/api/): OCaml standard library reference documentation

## Cookbook

- [Cookbook Index](https://ocaml.org/cookbook): Task-based code recipes for common programming tasks
- [Read and Write Files](https://ocaml.org/cookbook/read-and-write-text-file): File I/O recipes
- [Deserialise from JSON](https://ocaml.org/cookbook/deserialise-from-json): JSON parsing
- [Serialise to JSON](https://ocaml.org/cookbook/serialise-to-json): JSON generation
- [HTTP GET Request](https://ocaml.org/cookbook/http-get-request): Making HTTP requests
- [HTTP POST/PATCH with Auth](https://ocaml.org/cookbook/http-post-patch-request-bearer-auth): Authenticated HTTP requests
- [Parse Command-Line Arguments](https://ocaml.org/cookbook/parse-command-line-arguments): CLI argument parsing
- [Start a Web Server](https://ocaml.org/cookbook/start-a-web-server-hello-world): Basic web server
- [Web Server with HTML Templates](https://ocaml.org/cookbook/start-a-web-server-html-template): Templated web server
- [Read CSV](https://ocaml.org/cookbook/read-csv): CSV file parsing
- [SQLite Create/Insert/Select](https://ocaml.org/cookbook/sqlite-create-insert-select): SQLite database operations
- [Regular Expressions](https://ocaml.org/cookbook/regex-parse-date): Regex parsing
- [Random Values](https://ocaml.org/cookbook/generate-random-values): Random number generation
- [Sorting Lists and Arrays](https://ocaml.org/cookbook/sorting-lists-and-arrays): Sorting recipes
- [Run Commands and Process stdout](https://ocaml.org/cookbook/run-command-process-stdout): Shell command execution
- [TCP Client](https://ocaml.org/cookbook/tcp-client): TCP networking
- [TCP Server](https://ocaml.org/cookbook/tcp-server): TCP server implementation

## Exercises

- [Exercises](https://ocaml.org/exercises): Programming exercises with solutions, from beginner to advanced

## Books and Papers

- [Books](https://ocaml.org/books): Recommended books for learning OCaml
- [Papers](https://ocaml.org/papers): Academic papers about OCaml and its type system

## Platform and Tools

- [Platform Overview](https://ocaml.org/platform): The OCaml Platform tools ecosystem
- [Platform Roadmap](https://ocaml.org/tools/platform-roadmap): Current development roadmap
- [Compiler Release Cycle](https://ocaml.org/tools/compiler-release-cycle): How OCaml releases work
- [Native Compilation Target](https://ocaml.org/tools/native-target): Native code compilation
- [Bytecode Target](https://ocaml.org/tools/bytecode-target): Portable bytecode compilation
- [JavaScript Target](https://ocaml.org/tools/javascript-target): Compiling OCaml to JavaScript
- [WebAssembly Target](https://ocaml.org/tools/wasm-target): Compiling OCaml to Wasm
- [Unikernels Target](https://ocaml.org/tools/unikernel-target): Building MirageOS unikernels
- [The Opam Repository](https://ocaml.org/tools/opam-repository): The central package registry for OCaml
- [OCaml Infrastructure](https://ocaml.org/tools/ocaml-infrastructure): Tools and services running the OCaml ecosystem

## Packages

- [Package Search](https://ocaml.org/packages): Search the OCaml package repository (opam)
- [Package Pages](https://ocaml.org/p/dream/latest): Every opam package has a page at `https://ocaml.org/p/<name>/<version>` (or `latest`) with its README, dependencies, reverse dependencies, and API documentation under `/doc/`
- [GraphQL API](https://ocaml.org/graphiql): Query opam package metadata — including dependencies, reverse dependencies, and conflicts — by POSTing GraphQL queries to `https://ocaml.org/graphql` (this link is the interactive explorer)

## Releases

- [All Releases](https://ocaml.org/releases): OCaml compiler release history and changelogs
- [Changelog](https://ocaml.org/changelog): Release announcements for the compiler and platform tools

## Community

- [Community Hub](https://ocaml.org/community): Where to ask questions and get involved
- [OCaml Planet](https://ocaml.org/ocaml-planet): Aggregated blog posts and videos from the OCaml community
- [News](https://ocaml.org/news): OCaml community announcements
- [Events](https://ocaml.org/events): Meetups, conferences, and community events
- [Conferences](https://ocaml.org/conferences): OCaml Workshop and conference presentations
- [Jobs](https://ocaml.org/jobs): Job listings in the OCaml ecosystem
- [Industrial Users](https://ocaml.org/industrial-users): Companies using OCaml in production
- [Academic Users](https://ocaml.org/academic-users): Universities teaching OCaml and using it in research
- [Community Resources](https://ocaml.org/resources): Forums, chat, mailing lists, and other community spaces

## Feeds (Atom)

- [OCaml Planet Feed](https://ocaml.org/planet.xml): Blog posts aggregated nightly from across the OCaml ecosystem
- [News Feed](https://ocaml.org/news.xml): OCaml community announcements
- [Changelog Feed](https://ocaml.org/changelog.xml): Compiler and platform tool release announcements
- [Events Feed](https://ocaml.org/events.xml): Upcoming meetups and conferences
- [Jobs Feed](https://ocaml.org/jobs.xml): Job listings in the OCaml ecosystem

## Success Stories

- [Jane Street](https://ocaml.org/success-stories/large-scale-trading-system): OCaml's largest commercial user — 500+ OCaml programmers and 30M+ lines of OCaml power systems that safely trade billions of dollars a day. Jane Street built and open-sourced Dune, Core, and Async.
- [Ahrefs](https://ocaml.org/success-stories/petabyte-scale-web-crawling-and-data-processing): The world's third-largest web crawler, written in OCaml — 492.7 billion pages indexed across 500.4 million domains, serving 500 billion backend requests/day over 100+ PB of storage. A lean 150-person, $100M+ ARR company runs 4000+ servers on 1.5M lines of OCaml.
- [LexiFi](https://ocaml.org/success-stories/modeling-language-for-finance): Two decades of OCaml behind a leading derivatives-modelling platform. A small team has evolved a large codebase since the 2000s; LexiFi's contract-algebra technology is integrated into Bloomberg terminals.
- [Imandra](https://ocaml.org/success-stories/financial-compliance-with-automated-reasoning): Automated reasoning built entirely in OCaml. Goldman Sachs, Citi, DARPA, and the US Navy run Imandra's formally verified models in production, compressing FIX-protocol certification from days to hours.
- [Robur](https://ocaml.org/success-stories/secure-internet-services-with-ocaml-and-mirageos): A worker-owned collective building secure, resource-efficient MirageOS unikernels in OCaml — including a TLS stack, Mirage-Crypto, an OpenVPN implementation, and DNS and CalDav servers that run as unikernels.
- [Terrateam](https://ocaml.org/success-stories/infrastructure-as-code-platform): Open-source Infrastructure-as-Code SaaS built in OCaml, handling many concurrent GitHub/Terraform workflows with minimal CPU and memory across a small number of containers.

## About

- [About OCaml](https://ocaml.org/about): What is OCaml and why use it
- [History of OCaml](https://ocaml.org/history): The origins and evolution of OCaml
- [Governance](https://ocaml.org/governance): OCaml project governance structure
- [Security](https://ocaml.org/security): How to report security vulnerabilities in OCaml
- [OCaml Playground](https://ocaml.org/play): Try OCaml in the browser