.. image:: https://travis-ci.org/arximboldi/immer.svg?branch=master :target: https://travis-ci.org/arximboldi/immer :alt: Travis Badge .. image:: https://codecov.io/gh/arximboldi/immer/branch/master/graph/badge.svg :target: https://codecov.io/gh/arximboldi/immer :alt: CodeCov Badge .. image:: https://cdn.rawgit.com/arximboldi/immer/355a113782aedc2ea22463444014809269c2376d/doc/_static/sinusoidal-badge.svg :target: https://sinusoid.al :alt: Sinusoidal Engineering badge :align: right .. raw:: html Logotype .. include:introduction/start **immer** is a library of persistent_ and immutable_ data structures written in C++. These enable whole new kinds of architectures for interactive and concurrent programs of striking simplicity, correctness, and performance. .. _persistent: https://en.wikipedia.org/wiki/Persistent_data_structure .. _immutable: https://en.wikipedia.org/wiki/Immutable_object * **Documentation** (Contents_) * **Code** (GitHub_) * **CppCon'17 Talk**: *Postmodern Immutable Data Structures* (YouTube_, Slides_) * **ICFP'17 Paper**: *Persistence for the masses* (Preprint_) .. _contents: https://sinusoid.es/immer/#contents .. _github: https://github.com/arximboldi/immer .. _youtube: https://www.youtube.com/watch?v=sPhpelUfu8Q .. _slides: https://sinusoid.es/talks/immer-cppcon17 .. _preprint: https://public.sinusoid.es/misc/immer/immer-icfp17.pdf .. raw:: html This library has full months of *pro bono* research and development invested in it. This is just the first step in a long-term vision of making interactive and concurrent C++ programs easier to write. **Put your logo here and help this project's long term sustainability by buying a sponsorship package:** immer@sinusoid.al .. include:index/end Example ------- .. github does not support the ``literalinclude`` directive. This example is copy pasted from ``example/vector/intro.cpp`` .. code-block:: c++ #include int main() { const auto v0 = immer::vector{}; const auto v1 = v0.push_back(13); assert(v0.size() == 0 && v1.size() == 1 && v1[0] == 13); const auto v2 = v1.set(0, 42); assert(v1[0] == 13 && v2[0] == 42); } .. For a **complete example** check `Ewig, a simple didactic text-editor `_ built with this library. Why? ---- In the last few years, there has been a growing interest in immutable data structures, motivated by the horizontal scaling of our processing power and the ubiquity of highly interactive systems. Languages like Clojure_ and Scala_ provide them by default, and implementations for JavaScript like Mori_ and Immutable.js_ are widely used, specially in combination with modern UI frameworks like React_. Interactivity Thanks to *persistence* and *structural sharing*, new values can be efficiently compared with old ones. This enables simpler ways of *reasoning about change* that sit at the core of modern interactive systems programming paradigms like `reactive programming`_. Concurrency Passing immutable data structures by value does not need to copy any data. In the absence of mutation, data can be safely read from multiple concurrent processes, and enable concurrency patterns like `share by communicating`_ efficiently. Parallelism Some recent immutable data structures have interesting properties like :math:`O(log(n))` concatenation, which enable new kinds of `parallelization algorithms`_. .. _clojure: http://clojure.org/reference/data_structures .. _scala: http://docs.scala-lang.org/overviews/collections/overview.html .. _mori: https://swannodette.github.io/mori/ .. _immutable.js: https://github.com/facebook/immutable-js .. _react: https://facebook.github.io/react/ .. _reactive programming: https://en.wikipedia.org/wiki/Reactive_programming .. _share by communicating: https://blog.golang.org/share-memory-by-communicating .. _parallelization algorithms: http://docs.scala-lang.org/overviews/parallel-collections/overview.html Features -------- Idiomatic This library doesn't pretend that it is written in Haskell. It leverages features from recent standards to provide an API that is both efficient and natural for a C++ developer. Performant You use C++ because you need this. *Immer* implements state of the art data structures with efficient cache utilization and have been proven production ready in other languages. It also includes our own improvements over that are only possible because of the C++'s ability to abstract over memory layout. We monitor the performance impact of every change by collecting `benchmark results`_ directly from CI. .. _benchmark results: https://public.sinusoid.es/misc/immer/reports/ Customizable We leverage templates and `policy-based design`_ to build data-structures that can be adapted to work efficiently for various purposes and architectures, for example, by choosing among various `memory management strategies`. This turns *immer* into a good foundation to provide immutable data structures to higher level languages with a C runtime, like Python_ or Guile_. .. _python: https://www.python.org/ .. _guile: https://www.gnu.org/software/guile/ .. _policy-based design: https://en.wikipedia.org/wiki/Policy-based_design .. _memory management strategies: https://sinusoid.es/immer/memory.html Dependencies ------------ This library is written in **C++14** and a compliant compiler is necessary. It is `continuously tested`_ with Clang 3.8 and GCC 6, but it might work with other compilers and versions. No external library is necessary and there are no other requirements. .. _continuously tested: https://travis-ci.org/arximboldi/immer Usage ----- This is a **header only** library. You can just copy the ``immer`` subfolder somewhere in your *include path*. If you are using the `Nix package manager`_ (we strongly recommend it) you can just:: nix-env -if https://github.com/arximboldi/immer/archive/master.tar.gz Alternatively, you can use `CMake`_ to install the library in your system once you have manually cloned the repository:: mkdir -p build && cd build cmake .. && sudo make install .. _nix package manager: https://nixos.org/nix .. _cmake: https://cmake.org/ Development ----------- In order to develop the library, you will need to compile and run the examples, tests and benchmarks. These require some additional tools. The easiest way to install them is by using the `Nix package manager`_. At the root of the repository just type:: nix-shell This will download all required dependencies and create an isolated environment in which you can use these dependencies, without polluting your system. Then you can proceed to generate a development project using `CMake`_:: mkdir build && cd build cmake .. From then on, one may build and run all tests by doing:: make check In order to build and run all benchmarks when running ``make check``, run ``cmake`` again with the option ``-DCHECK_BENCHMARKS=1``. The results of running the benchmarks will be saved to a folder ``reports/`` in the project root. License ------- **This software is licensed under the Boost Software License 1.0**. .. image:: https://upload.wikimedia.org/wikipedia/commons/c/cd/Boost.png :alt: Boost logo :target: http://boost.org/LICENSE_1_0.txt :align: right The full text of the license is can be accessed `via this link `_ and is also included in the ``LICENSE`` file of this software package.