Fletch is an experimental runtime for Dart that makes it possible to implement highly concurrent programs in the Dart programming language. To make it easier to reason about such programs, Fletch comes with a virtual machine implementation that encourages synchronous operations over asynchronous ones - and enables lots of user-level threads to be blocked without holding on to too many resources.

Fletch is very much incomplete. We'd be very happy to hear about things that work well and areas that need more work, but don't expect to be able to build products on top of it.

To try out Fletch, you need to first build it. Once you have working fletch-vm and fletch executables, running Dart code on top of it is as easy as typing:

$ fletch compile-and-run hello.dart

To give us feedback, please file issues on GitHub or join our mailing list and post there. We also welcome contributions; just sign our CLA, fork our repository, and start sending us pull requests.

The Fletch runtime for Dart is available under the Modified BSD license. For all the details, see the separate license file.