We've covered a lot of ground in the last forty or so chapters. In the final part of the book we're going to walk through creating a Vim plugin for a programming language from scratch.
This is not for the faint of heart. It's going to take a lot of effort.
If you want to stop now, that's completely fine! You've already learned enough
to make serious enhancements to your own ~/.vimrc file and to fix bugs you
find in other people's plugins.
There's no shame in saying "that's enough for me, I don't want to spend hours of my life creating plugins I won't use very often". Be practical. If you can't think of a full plugin you want to make, stop now and come back when you do.
If you do want to continue make sure you're ready to devote some time. The rest of the book is going to be intense, and I'm going to assume you actually want to learn, not just coast through the chapters reading them on your couch.
The plugin we're going to make is going to add support for the Potion programming language.
Potion is a toy language created by _why the lucky stiff before his disappearance. It's an extremely small language which makes it ideal for our purposes.
Potion feels a lot like Io, with some ideas from Ruby, Lua, and other languages mixed in. If you've never tried Io it may seem weird. I strongly recommend playing with Potion for at least an hour or two. You won't use it in real life, but it might change the way you think and expose you to new ideas.
The current implementation of Potion has a lot of rough edges. For example: if you mess up the syntax it usually segfaults. Try not to get too hung up on this. I'll provide you with lots of sample code that works so you can focus mostly on the Vimscript and not Potion.
The goal is not to learn Potion (though that can be fun too). The goal is to use Potion as a small example so we can touch on a lot of different aspects of writing full Vim plugins.
Download and install Potion. You're on your own for this one. It should be fairly simple.
Make sure you can get the first couple examples in the pamphlet working in the
Potion interpreter and by putting them in a .pn file. If it seems like the
interpreter isn't working check out this
issue for a possible cause.