TextMate, which is considered to be one of the best text editors for Mac, has gone open source. In less than 24 hours, over 500 branches/forks have already been created and many improvements are already landing into the codebase.
We reported that the application can come to Linux. However it turns out that it is really really difficult to port it over to Linux.
TextMate uses Objective-C and Cocoa framework. Developers will have to rewrite a lot of parts of the code because there is no cocoa framework on Linux.
There is an open source alternative for Cocoa, GNUStep. But it isn't exactly up to par with Cocoa, and porting the whole editor from Obj-C/Cocoa to C++/Qt or C/Gtk would be a pretty huge task.
A feature request for a Linux port was filed on GitHub, but it has been closed as it is nearly impossible to do. Of course, if someone decides to take on such a big task, it can come to Linux in future but chances are very bleak.