rust-lang/rust 0.4

Rust 0.4

on GitHub

~2000 changes, numerous bugfixes

Syntax

• All keywords are now strict and may not be used as identifiers anywhere
• Keyword removal: 'again', 'import', 'check', 'new', 'owned', 'send', 'of', 'with', 'to', 'class'.
• Classes are replaced with simpler structs
• Explicit method self types
• ret became return and alt became match
• import is now use; use is now extern mod`
• extern mod { ... } is now extern { ... }
• use mod is the recommended way to import modules
• pub and priv replace deprecated export lists
• The syntax of match pattern arms now uses fat arrow (=>)
• main no longer accepts an args vector; use os::args instead

Semantics

• Trait implementations are now coherent, ala Haskell typeclasses
• Trait methods may be static
• Argument modes are deprecated
• Borrowed pointers are much more mature and recommended for use
• Strings and vectors in the static region are stored in constant memory
• Typestate was removed
• Resolution rewritten to be more reliable
• Support for 'dual-mode' data structures (freezing and thawing)

Libraries

• Most binary operators can now be overloaded via the traits in `core::ops'
• std::net::url for representing URLs
• Sendable hash maps in core::send_map
• `core::task' gained a (currently unsafe) task-local storage API

Concurrency

• An efficient new intertask communication primitive called the pipe, along with a number of higher-level channel types, in core::pipes
• std::arc, an atomically reference counted, immutable, shared memory type
• std::sync, various exotic synchronization tools based on arcs and pipes
• Futures are now based on pipes and sendable
• More robust linked task failure
• Improved task builder API

Other

• Improved error reporting
• Preliminary JIT support
• Preliminary work on precise GC
• Extensive architectural improvements to rustc
• Begun a transition away from buggy C++-based reflection (shape) code to Rust-based (visitor) code
• All hash functions and tables converted to secure, randomized SipHash