Building the Hack Typechecker

Typechecker (hh_server and hh_client)

Basically, follow the distro-specific instructions for building HHVM. Make sure you have OCaml installed and available, at least version 3.12; the apt-get or yum install line in the directions may already install a proper package for you. If OCaml is available, cmake will detect this and build the typechecker as part of the HHVM build. (You can inspect the cmake output to make sure this was detected properly.)

Once HHVM is built, the Hack typechecker will be available at hphp/hack/bin/hh_server and hphp/hack/bin/hh_client. Make sure you add this directory to your $PATH or otherwise ensure both binaries are on your $PATH -- hh_client will not be able to find hh_server otherwise!

Conversion tools (hackificator and hack_remove_soft_types)

These unfortunately have some more difficult external dependencies. First, build HHVM and the Hack typechecker. Then, read hphp/hack/tools/README for further directions on getting these tools set up. They are not integrated into the main build system and must be compiled separately.