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Dart 1.24: Faster edit-refresh cycle on the web & new function type syntax

Dart 1.24 is now available. It includes the Dart Development Compiler and supports a new generic function type syntax. Get it now!


Figure 1: DDC debugging in Chrome.

Some notable changes in this release:
  • pub serve now has support for the Dart Development Compiler. Unlike dart2js, this new compiler is modular, which allows pub to do incremental re-builds for pub serve.
    • In practice what that means is you can edit your Dart files, refresh in Chrome (or other supported browsers), and see your edits almost immediately. This is because pub is only recompiling your package, not all packages that you depend on.
    • There is one caveat with the new compiler, which is that your package and your dependencies must all be strong mode clean.
    • You can also use the new compiler to run your tests in Chrome much more quickly than you can with dart2js.
    • Read more in the changelog.
  • You can now publish packages that depend on the Flutter SDK to pub. Moreover, pub.dartlang.org has started tagging Flutter plugins with an icon, and there is a new landing page — pub.dartlang.org/flutter/plugins — that lists all of them.
  • Generic function type syntax allows developers to specify generic function types everywhere a type is expected, including type annotations, return types, actual type arguments, and formal type parameter bounds.
    • Example: typedef F = List<T> Function<T>(T);.
    • Read more in the spec.
  • It is now type correct to have void f() => ++x; (functions and setter declared using => with return type void now allow the returned expression to have any type).
  • The deprecated ChunkedConverter class has been removed.
  • Dartium was updated to align with Chrome v50 (versus v45), which brings support of window.isSecureContext and window.requestIdleCallback, among other things.
  • As of this release, we'll show a warning when using the MIPS architecture. Unless we learn about any critical use of Dart on MIPS in the meantime, we're planning to deprecate support for MIPS starting with the next stable release.
For more information, see the changelog.

Please download the latest release and let us know what you think!

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Posted by Seth Ladd

(This is an "oldie but a goodie" misc@dartlang.org post originally written by Bob Nystrom. It is being posted here as the explanations still ring true.)

Bob writes:


"static", "final", and "const" mean entirely distinct things in Dart:

"static" means a member is available on the class itself instead of on instances of the class. That's all it means, and it isn't used for anything else. static modifies *members*.

"final" means single-assignment: a final variable or field *must* have an initializer. Once assigned a value, a final variable's value cannot be changed. final modifies *variables*.

"const" has a meaning that's a bit more complex and subtle in Dart. const modifies *values*. You can use it when creating collections, like const [1, 2, 3], and when constructing objects (instead of new) like const Point(2, 3). Here, const means that the object's entire deep state can be determ…