Compiling CAF requires CMake and a recent C++ compiler. To get and compile the sources on UNIX-like systems, type the following in a terminal:

git clone https://github.com/actor-framework/actor-framework
cd actor-framework
make -C build
make -C build install [as root, optional]

Running configure is not a mandatory step. The script merely automates the CMake setup and makes setting build options slightly more convenient. On Windows, use CMake directly to generate an MSVC project file.


  • Lightweight, fast and efficient actor implementations

  • Network transparent messaging

  • Error handling based on Erlang’s failure model

  • Pattern matching for messages as internal DSL to ease development

  • Thread-mapped actors for soft migration of existing applications

  • Publish/subscribe group communication

Supported Operating Systems

  • Linux

  • Windows

  • macOS

  • FreeBSD

Hello World Example

// The obligatory "Hello World!" example.

#include "caf/actor_ostream.hpp"
#include "caf/actor_system.hpp"
#include "caf/caf_main.hpp"
#include "caf/event_based_actor.hpp"

#include <iostream>
#include <string>

using namespace caf;
using namespace std::literals;

behavior mirror(event_based_actor* self) {
  // return the (initial) actor behavior
  return {
    // a handler for messages containing a single string
    // that replies with a string
    [self](const std::string& what) -> std::string {
      // prints "Hello World!" via aout (thread-safe cout wrapper)
      aout(self).println("{}", what);
      // reply "!dlroW olleH"
      return std::string{what.rbegin(), what.rend()};

void hello_world(event_based_actor* self, const actor& buddy) {
  // send "Hello World!" to our buddy ...
  self->request(buddy, 10s, "Hello World!")
      // ... wait up to 10s for a response ...
      [self](const std::string& what) {
        // ... and print it
        aout(self).println("{}", what);

void caf_main(actor_system& sys) {
  // create a new actor that calls 'mirror()'
  auto mirror_actor = sys.spawn(mirror);
  // create another actor that calls 'hello_world(mirror_actor)';
  sys.spawn(hello_world, mirror_actor);
  // the system will wait until both actors are done before exiting the program

// creates a main function for us that calls our caf_main