Hack Documentation

• Getting Started

  • Getting Started

    Installing Hack, running your first program, and introducing the tools.

  • Source Code Fundamentals

    Basic syntax, namespaces, and the autoloader.

  • Expressions And Operators

    Expressions, operators, associativity, and precedence.

  • Arrays And Collections

    Immutable collections, mutable collections, and APIs.

  • Contexts And Capabilities

    Specifying capabilities and permissions for functions.

  • Modules

    Language support for organizing code.

  • Packages

    Combine modules into separate builds and deployments.

  • XHP

    Safe, composable HTML templating.

  • Silencing Errors

    HH_FIXME best practices and error codes.

  • Contributing

    How to contribute to this website.

• Control Flow

  • Statements

    Simple statements, blocks, and loops.

  • Asynchronous Operations

    Asynchronous functions, await, and the concurrent keyword.

  • Readonly

    Specialized feature for performantly controlling object mutability

• Classes, Interfaces, Traits

  • Functions

    Named functions, anonymous functions and parameters.

  • Classes

    Classes provide a way to group functionality and state together.

  • Traits And Interfaces

    Mechanisms for code reuse and code constraint within classes.

  • Attributes

    Attaching metadata to Hack programs, built-in attributes and defining your own.

• Types and Generics

  • Types

    The type checker.

  • Built In Types

    Built-in types known to the type checker.

  • Generics

    Generic types, where constraints, and variance.

  • Reified Generics

    Generics with type information accessible at runtime.

• Experimental Additions

  • Experimental Features

    Enable features in the experimental phase.

  • Expression Trees

    Typechecker support for domain specific languages.

  • Memoization Options

    Experimental feature for controlling use of memoization and the Implicit Context

Built-in API Reference

Full reference docs for all functions, classes, interfaces, and traits in the Hack language.

Standard Library API Reference

Full reference docs for all functions, classes, interfaces, and traits in the Hack Standard Library.