Awesome OCaml

Everything you'll ever need on the road to mastering OCaml.

A curated list of references to awesome OCaml tools, frameworks, libraries, and articles. Additionally, there is a collection of freely available books, papers, and presentations.

If you're looking for comprehensive community-driven content about OCaml, visit 📚OCamlverse!

For a quick introduction to the modern OCaml development workflow, consult the Up and Running with OCaml tutorial.

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Community
Algorithms and Data Structures
Application Libraries
Benchmarking
Blogs
Books
Videos
Code Analysis and Linters
Compilers and Compiler Tools
Concurrency
Databases
Datetime
Developer Tools
Exercises and Short Examples
Formal Software Verification
General
Graphics
Internationalization
User Interface
Language-related
Large Source Code Examples
Logging
Machine Learning
Messaging
Metaprogramming
Metrics
Mobile Applications
Networking
Online Courses
Package Management
Parallelism
Project Starter Templates
Printers helpers
Questions
Regular Expressions
Science and Technical Computing
Security and Cryptography
Semantic Technology
Serialization
System Programming
Testing
Utilities
Web Development

Community

Algorithms and Data Structures

Comparing a Machine Learning Algorithm Implemented in F# and OCaml
OCamlgraph – A generic graph library for OCaml.
ods – A large collection of data structures and algorithms for OCaml.
combine – OCaml library for combinatorics https://www.lri.fr/~filliatr/combine/.
Decompress - A pure OCaml implementation of Zlib.
Ke - Fast implementation of queue (FIFO) in OCaml.
Duff - Implementation of Rabin's fingerprint and delta compression by P. MacDonald in OCaml (same as libXdiff
ORaft - Library of Raft consensus algorithm implemented in OCaml
ODiff – Library of YIQ NTSC transmission image difference alghoritm implemented in OCaml and ReasonML.

Application Libraries

Batteries Included – A community-maintained foundation library for your OCaml projects.
Cmdliner – Declarative definition of command line interfaces for OCaml.
Core – Jane Street Capital's full-fledged standard library overlay. A portable subset of Core is also available: Core_kernel.
Base - Jane Street Capital's dependency-free, quick-compiling, fully-portable across any environment that can run OCaml code standard library.
React – React is an OCaml module for functional reactive programming (FRP). It provides support for programs with time-varying values, declarative events, and signals.
Minicli – Minimalist library for command-line parsing.
easy-format – Pretty-printing library for OCaml.
ocaml-rpc – Light library to deal with RPCs in OCaml.
ocaml-containers – A lightweight, modular standard library extension, string library, and interfaces to various libraries (bigarrays, Unix, etc.) BSD license.

Benchmarking

core_bench – Micro-benchmarking library for OCaml by Jane Street. - Getting Started with Core_bench
benchmark – Benchmarking functions for measuring the run-time of functions using latency or throughput.

Blogs

Books

More OCaml: Algorithms, Methods, and Diversions – In More OCaml, John Whitington takes a meandering tour of functional programming with OCaml, introducing various language features and describing some classic algorithms. The book ends with a large-scale example dealing with the production of PDF files. There are questions for each chapter, along with worked-out answers and hints.
How to Think Like a (Functional) Programmer by Allen Downey and Nicholas Monje – How to Think Like a Computer Scientist is an introductory programming textbook based on the OCaml language. It is a modified version of Think Python by Allen Downey. It is intended for newcomers to programming and also those who know some programming but want to learn programming in the function-oriented paradigm, or those who simply want to learn OCaml.
OCaml from the Very Beginning by J. Whitington - OCaml from the Very Beginning will appeal both to new programmers and experienced programmers eager to explore functional languages such as OCaml.
Pearls of Functional Algorithm Design by Richard Bird - It summarizes 30 hard algorithmic problems in the function programming world. Although it is for Haskell, the algorithm problems are very interesting, and trying to solve them in OCaml also helps the thinking of functional programming. Partial solutions in OCaml are here.
Real World OCaml by Y. Minsky, A. Madhavapeddy, and J. Hickey - Functional Programming for the masses.
Unix System Programming in OCaml by X. Leroy and D. Rémy – Introduction to Unix Systems Programming, with an emphasis on communications between processes.
Using, Understanding, and Unraveling OCaml – This book describes both the OCaml language and the theoretical grounds behind its powerful type system.
Purely Functional Data Structures - This is the first or only book focus on various data structures in FP world. A must-read one.
OCaml for Scientists - by Jon Harrop.
OCaml Programming: Correct + Efficient + Beautiful - Textbook on Functional Programming and Data Structures in OCaml - by Michael R. Clarkson et al.

Videos

- OCaml Programming: Correct + Efficient + Beautiful - List of 200 bite-sized videos recorded by Michael R. Clarkson. It can be watched independently of the textbook titled the same and listed above in the Books section.

Code Analysis and Linters

Mascot - Mascot is a style-checker for OCaml sources.
pfff – pfff is a set of tools and APIs to perform some static analysis, dynamic analysis, code visualizations, code navigations, or style-preserving source-to-source transformations such as refactorings on source code.
Infer - Infer is a static analyzer for Java, C and Objective-C
Frama-C - Frama-C is a static analysis and formal proof framework for C and C++.
flow - flow is a static type checker for JavaScript.
SLAyer - SLAyer is an automatic formal verification tool that uses separation logic to verify memory safety of C programs.
MemCAD - MemCAD is an abstract interpreter for shape analysis. MemCAD can verify C programs manipulating complex data structures.
Camelot - Camelot is a modular and fully configurable OCaml linter and stylechecker.
coq-of-ocaml - Translator from OCaml to Coq to formally verify OCaml code.
MOPSA - MOPSA is a generic framework for building sound static analyzers based on the theory of abstract interpretation.

Program analysis

BAP - BAP is a reverse engineering and program analysis platform that targets binary programs.
BinCat - BinCat is a binary code static analysis toolkit.
cwe_checker - cwe_checker finds vulnerable patterns in binary executables.

Compilers and Compiler Tools

Languages and Compilers:
- Caramel - Caramel is a functional language for building type-safe, scalable, and maintainable applications.
- cDuce - cDuce is a modern XML-oriented functional language with innovative features.
- Compcert C Compiler - It is a C Compiler supporting most of the ISO C90 and C99 / ANSI C features.
- Eff Programming Language - Eff is a functional language with handlers of not only exceptions, but also of other computational effects such as state or I/O.
- Hack Programming Language
- Haxe Programming Language
- Neko Programming Language - Originally the compiler was written in OCaml.
- Mazeppa - A modern supercompiler for call-by-value functional languages.
- Mezzo Programming Language - Mezzo is a programming language in the ML tradition, which places strong emphasis on the control of aliasing and access to mutable memory.
- OCaml-Java - OCaml to Java bytecode compiler.
- Opa Programming Language
- Rhine – A Lisp on LLVM written in OCaml.
- Rust Programming Language - Originally written in OCaml before bootstrapping.
- Quick C-- Target Language - It is now a dead project. Github Repo. Alternative website.
- tis-interpreter - An interpreter for finding subtle bugs in programs written in standard C
- Reason - Friendly syntax & toolchain for OCaml by Facebook.
- RaML - Resource Aware ML (RaML) is a tool that automatically and statically computes resource-use bounds for OCaml programs.
- Liquid ML - Shopify's Liquid Templating language for OCaml.
Parser and Lexer Generators:
- Opal – Self-contained monadic parser combinators for OCaml.
- Sedlex is a modern, encoding-agnostic (read: Unicode-supporting) lexer generator (the ppx-based successor to ulex.)
- Menhir – Menhir is a LR(1) parser generator for OCaml.
  - See ocaml-parsing for a clearer example of using Menhir and Sedlex to produce a useful parser,
  - ... and Obelisk, a neat project to produce readable LaTeX, HTML, or plain-text EBNF-style documentation for your grammar.
- ocamllex/ocamlyacc – lex and yacc implementation for OCaml.
- Angstrom - Parser combinators built for speed and memory efficiency
Articles:
- Kaleidoscope: Implementing a Language with LLVM in Objective Caml¶

Concurrency

Two concurrency libraries exist in OCaml: Lwt and Async. They provide very similar functionality but make radically different decisions with regards to error handling and internal implementation details (see the links below for more details). Real World OCaml uses Async, but a version of the code examples translated to Lwt is also available.

Libraries:
- Lwt — A cooperative threads library for OCaml.
- Async — A monadic concurrence library to go with the Core library.
Articles:
- [The blog post that introduced