What is Hack, why should you care, and how to get started.

1. Intro to Hack
Kyle Ferguson
@kylegferg
docs.hhvm.com

2. Hack
- Programming language for HHVM
- Evolved from PHP

3. Benefits
- Created by Facebook, open source
- If you know PHP, you know Hack
- Easy to adopt (even w/ existing code base)
- Language additions (generics, collections, etc.)

4. PHP (dynamic)
- Rapid development cycle
- Easily deployed
- Highly available
Java/C++ (static)
- Disciplined
- Scales better
Goals for Hack

5. Introducing Hack

6. What gets “typed”
Members
Parameters
Returns
Types
Primitive: string, int, bool, array
Nullable: ?string, ?FooInterface
Classes: Validator, FooInterface
Other: mixed, void, this
Also see: closures, collections,
generics, constraints
Tuples: (string, int)

7. Modes
Partial (default)!
!
- Nothing is *required* to have types defined
- Allows for incremental adoption
Strict!
!
- EVERYTHING must be typed
Decl!
!
- Allows “Strict” code to work with legacy code
- Always avoid this mode if possible

8. Unpredictable code is DANGEROUS
Hack provides a *more* predictable PHP

9. Migrating

10. Migrating

11. Migrating

12. Migrating

13. Migrating

14. Migrating

15. Tools / Help
Documentation docs.hhvm.com
Editor plugins: Vim, Emacs
Example Site: github.com/hhvm/hack-example-site
Dev Environment: github.com/senary/harbor