Owl is a portable Wayland compositor written in Objective-C, using Cocoa as its backend. Owl primarily targets Mac OS X, but also supports a variety of other operating systems thanks to GNUstep.
Owl makes it possible to run Wayland clients inside OS X's native Quartz graphics environment. In that sense, Owl plays a role similar to the XQuartz and XWayland compatibility layers.
Owl is a work in progress. Some things work, many don't. There's a lot to improve and figure out!
First, make sure you have Wayland installed. Please see the other repositories in this GitHub organization for ports of Wayland and related software to systems that they don't normally support.
To build Owl, create a build directory, then run configure, then make:
$ mkdir build
$ cd build
$ ../configure
Owl root directory detected as ..
$ make
If the build succeeds, you should find Owl.app in the build directory.
Owl is free software, available under the GNU General Public License version 3 or later.