esy-hack-example

This demonstrates workflow using esy with hack/hhvm.

This depends on homebrew installed version of hhvm, see hhvm/package.json which exposes installation into esy environment. If you have other version installed or you are trying this on Linux then you need to modify paths there to adhere to your system. The idea is that won't be needed if hack/hhvm could provide some means to communicate its installation location to esy.

To try it out:

% npm install -g esy@next
% git clone https://github.com/andreypopp/esy-hack-example
% cd esy-hack-example
% esy install
% esy build
% esy hhvm ./main.php

Notice how the project is split into main package and dependency (in ./fib subdirectory). Currently we use link: to bring the dependency into project but we could instead fetch it from npm/github/...

How hhvm finds dependencies

Packages with Hack code export $PHP_INCLUDE_PATH environment variable which contain include_path "fragment". See fib/package.json.
hhvm package wraps original hhvm executable and adds
```
-d include_path="$PHP_INCLUDE_PATH"
```
to the invocation. Thus esy hhvm invocation sees all Hack code installed by Hack packages.

TODO

Better integration with system installed hhvm.

We need to expose information about installed hhvm version to dependency solver, see esy/esy#847 for a good proposal on that.
Example with native code extension.